The catheter flushing method increases the diagnostic yield of brushing cytology for biliary strictures

The catheter flushing method increases the diagnostic yield of brushing cytology for biliary strictures | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The catheter flushing method increases the diagnostic yield of brushing cytology for biliary strictures Sung Ill Jang, Min Je Sung, Ji Hae Nahm, Seok Jeong, Tae Hoon Lee, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3911988/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background and Aim: Endobiliary brushing is usually performed in the diagnosis of indeterminate biliary strictures; however, in this setting, brush cytology is limited by a low diagnostic yield and sensitivity. Here, we evaluated whether the catheter flushing method (CFM) could improve cellularity and diagnostic performance compared with the conventional cytologic method (CCM). Methods: Endobiliary brushings were obtained during endoscopic retrograde cholangiopancreatography (ERCP) from patients with biliary strictures enrolled at six tertiary hospitals. Additional CFM was performed after brushing. Using liquid-based cytologic preparations of samples, we assessed the diagnostic performance of the CCM using Pap staining and the CFM using methionyl-transfer RNA synthetase 1 (MARS1) immunofluorescence staining. Results: From a total of 399 patients (malignant, 253; benign, 146), 374 CCM samples and 361 CFM samples contained adequate cells, with no significant difference in diagnostic yield (93.7% vs. 90.5%, respectively, P = 0.721). The sensitivity of the CFM (90.3%) was significantly higher than that of the CCM (75.1%; P < 0.001), with no significant difference in accuracy between methods (81.2% vs. 82.6%, respectively; P = 0.608). Conclusions: Diagnostic yield was equivalent between CCM and CFM. Also, the high sensitivity and similar accuracy of the CFM compared with the CCM indicates that the CFM could be an additional brush cytology method for detecting malignancy in patients with indeterminant biliary strictures. Further prospective studies are needed to validate these findings. catheter flushing method brush cytology ERCP indeterminate biliary stricture Figures Figure 1 Figure 2 Figure 3 INTRODUCTION Biliary strictures can occur in the biliary tract due to a variety of etiologies, ranging from benign conditions to malignancies. [ 1 ] Despite the availability of various imaging modalities such as abdominal ultrasound, endoscopic ultrasound, computed tomography (CT), and magnetic resonance imaging, it is often difficult to determine the etiology of biliary strictures by imaging alone. Thus, pathologic confirmation is necessary for accurately diagnosing indeterminate biliary strictures, especially with suspicion of biliary tract cancer. Brush cytology is routinely performed during endoscopic retrograde cholangiopancreatography (ERCP) to determine the malignancy of biliary strictures. [ 2 ] However, the sensitivity of endoscopic brush cytology is as low as 20–40%. [ 3 – 5 ] Some researchers propose that the low sensitivity of brush cytology is mainly due to inadequate cellular sampling, although a false-negative diagnosis can occur when there is insufficient cellularity regardless of the sampling technique used. [ 3 , 6 ] To improve the diagnostic yield, various endoscopic techniques have been proposed to diagnose cancer using cytology, including bile aspiration and examination of cells in the side flaps of biliary stents. [ 7 – 9 ] Foutch et al. were the first to describe endobiliary brushing over a guidewire, [ 10 ] with later studies reporting that brush cytology is superior to simple aspiration of bile for the diagnosis of malignant strictures. [ 11 , 12 ] Specifically, Foutch et al. found that the sensitivity of brush cytology (33%) was higher than that of simple aspiration from bile (6%). To further increase the cancer detection rate of brush cytology, both dilatation of the stricture and endoscopic needle aspiration have been performed together. [ 13 , 14 ] However, one study reports that using a pneumatic balloon or graduated dilating catheter does not increase the detection rate of brush cytology, whereas repeat brushing increases the diagnostic yield. [ 14 ] Furthermore, although using a longer cytology brush enhances cellularity, it does not improve the cancer detection rate compared with a standard brush. [ 15 ] There has also been an attempt to sample bile duct strictures using dedicated basket grasping instead of brushing. [ 16 ] In addition, post-brushing biliary lavage fluid cytology was found to be superior to bile aspiration or brush smear. [ 17 ] Recently, multiple studies show that flushing the catheter sheath after the brush is removed increases the yield of ERCP biliary brush cytology and thereby improves diagnostic performance. [ 18 – 20 ] Wakasa et al. found that the combination of conventional smear with brush washing and flushing the sheath tube contents increases diagnostic accuracy (78.7%) compared with conventional smear procedures alone (68.8%). [ 18 ] Nur et al. report that ERCP brush cytology performed together with cutting the cytology brush and flushing the catheter sheath produces a high diagnostic yield (84%). [ 19 ] Moreover, Amog-Jones et al. found that the combination of brushing and sheath tube rinsing produced moderate-to-high cellularity in 10 of 13 (77%) specimens. [ 20 ] However, a clinically confirmative and effective method to increase the diagnostic yield of brush cytology has not been established. Here, we compared the diagnostic performance of the catheter flushing method (CFM) versus the conventional cytologic method (CCM) during ERCP in patients with indeterminate biliary strictures. METHODS Study design This retrospective study was conducted at six tertiary medical centers. The study protocol was approved by the institutional review boards at all six facilities (3-2020-0005). The primary outcome was diagnostic performance in terms of diagnostic yield, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy. The study data were accessible to all authors, each of whom reviewed and approved the final version of this manuscript. Patient selection Inclusion criteria were as follows: biliary stricture confirmed by imaging (CT, magnetic resonance imaging, or positron emission tomography), brush cytology, and intraductal biopsy sampling by ERCP or surgical specimens; age ≥ 19 years; and no prior procedures involving the papilla. Exclusion criteria were as follows: age ≤ 18 years, pregnancy, intellectual disability, sensitivity to contrast agent, acute cholangitis, and past pancreatobiliary surgery. Diagnostic procedures ERCP was used to collect bile duct brushings (GRBH-230-3-3.5 brush; Wilson-Cook Medical Inc, Winston-Salem, NC, USA) by making five to eight passes over the lesions (Fig. 1 A, B). To prepare the CCM sample, the brush was washed in a container filled with Roswell Park Memorial Institute-1640 medium (Gibco BRL, Thermo Fisher Scientific, Waltham, MA, USA) (Fig. 1 C–E). To prepare the CFM sample, the brush was cut at the wire using surgical scissors into a second container with preservative (Pro-Fixx; Lerner Laboratories, Pittsburgh, PA, USA) (Fig. 1 F). After removing the wire, a 10-mL syringe with normal saline was used to flush residual sample from the catheter sheath into the second container (Fig. 1 G–I), which was then wrapped in aluminum foil and stored at 20°C. [ 21 ] After collection, samples were immediately transferred to the cytology laboratory for liquid-based ThinPrep (Cytyc Corp, Marlborough, MA, USA) slide preparation. Assessment of cellularity Quantitative analysis of cellularity, defined as the presence of cellular material, was performed for each sample. Cellularity was evaluated by assigning a grade based on the number of epithelial cells observed on each slide. Grade 0 indicates insufficient epithelial cells for interpretation (< 20% of slide study area covered by epithelial cells); grade 1 indicates limited cellular material (20–50% of slide study area covered by epithelial cells); grade 2 indicates good cellularity (50–80% of slide study area covered by epithelial cells); and grade 3 indicates cellularity (> 80% of slide study area covered by epithelial cells). Grades 0 and 1 were considered inadequate due to the limited amount of material available for interpretation, whereas grades 2 and 3 were considered adequate. Immunofluorescence staining For methionyl-transfer RNA synthetase 1 (MARS1) immunofluorescence staining of CFM samples, liquid-based ThinPrep slides were permeabilized in 0.3% phosphate-buffered saline containing Tween (Sigma-Aldrich, St. Louis, MO, USA) for 30 min. After two to three washes with Tris-buffered saline solution including 0.5% Tween 20 (TBS-T), slides were rinsed with distilled water and blocked for 20 min at room temperature with 3% goat serum. Slides were then incubated for 1 h at 37°C with anti- MARS1 primary antibody (1:100; BICBIO, Suwon, South Korea). After two to three washes with TBS-T, slides were incubated with secondary antibody (anti-mouse antibody Alexa Fluor 488 conjugate, 1:300; Thermo Fisher Scientific, Eugene, OR, USA) for 30 min at room temperature. The final two to three washes with TBS-T were followed by 4′,6-diamidino-2-phenylindole (Molecular Probes, Thermo Fisher Scientific) counterstaining. [ 21 , 22 ] Interpretation of sample staining The categories were dichotomized into adequate (cellularity grade 2 or 3) and inadequate (cellularity grade 0 or 1) groups (Fig. 2 , 3 ), and diagnostic yield was defined as the number of brush samples in the adequate group. Three pathologists (JHN, JMK, and HDC) blinded to clinical data and Papanicolaou (Pap) staining results independently examined all cellularity of brush samples. Brush cytologic specimens were classified into six categories: nondiagnostic, negative for malignancy, atypical, neoplastic (benign or other), suspicious for malignancy, and malignancy. [ 23 ] The 'neoplastic (benign or other)' category is typically assigned to cases suspected of being pancreatic neoplasms, which include pancreatic neuroendocrine tumors, solid pseudopapillary neoplasms, intraductal papillary neoplasms, and mucinous cystic neoplasms. Consequently, such cases were not included in this study. MARS1 immunofluorescence-stained slides were assessed in conjunction with positive (TKF-1 cells) and negative (NIH 3T3 cells) control slides. A fluorescent microscope (BX53; Olympus Corp, Tokyo, Japan) was used to view entire fields of cytologic slides at a magnification of at least 200×. Positive MARS1 staining was defined as more than one cell cluster with a high immunofluorescence signal in the cytoplasm or plasma membrane (i.e., fluorescence intensity similar to or stronger than that of positive control cells) at a magnification of at least 200×. Weak or ambiguous staining of epithelial cells was considered negative. Three pathologists blinded to clinical data and Papanicolaou (Pap) staining results independently examined all MARS1 immunofluorescence-stained cytologic tissues. Any discrepancy was resolved through collaborative examination of specimens. [ 21 ] Clinicopathologic diagnoses For analytic purposes, based on CCM Pap staining, the malignant and suspicious malignancy categories were combined into a malignant subset, and the atypical and negative malignancy categories were combined into a nonmalignant subset. Suspicious for malignancy is an extremely high-risk cytologic diagnostic. [ 24 ] MARS1 immunofluorescence staining was considered positive or negative, and indeterminate biliary strictures were defined as those whose etiology remained unknown after ultrasound, CT, ERCP, or cytologic assessment. [ 25 ] Brush cytology, intraductal biopsy sampling, biopsy sampling of metastatic lesions, and/or surgical specimen findings were used to determine the final clinicopathologic diagnosis. If a pathologic diagnosis could not be made, the final diagnosis relied on clinical and radiologic data collected during at least a 12-month period of follow-up. In summary, malignant biliary strictures were confirmed pathologically using brush cytology, intraductal biopsy sampling, biopsy sampling of metastatic lesions, and/or surgical specimens. Benign biliary strictures were diagnosed clinically or radiologically with at least 12 months of clinical follow-up. Statistical analysis The diagnostic yield was analyzed using the χ2 test. The McNemar test was used to assess sensitivity, specificity, PPV, NPV, and accuracy with a P -value < 0.05 indicating statistical significance. The Cochran-Mantel-Haenszel test and logistic regression with the generalized estimating equation (extended McNemar approach) were used to compare diagnostic performance. SPSS version 27 for Windows software (IBM Inc, Armonk, NY, USA) was used for statistical analysis. RESULTS Patient characteristics In total, 399 patients with biliary stricture were included in the study. Mean patient age was 68.5 years, and there were more male than female patients (Table 1 ). Malignancy was detected in 253 biliary strictures (63.4%), the most common of which was cholangiocarcinoma (n = 214, 53.6%). The other 146 biliary strictures (36.6%) were considered benign and were most commonly considered idiopathic (n = 71, 17.8%). Table 1 Characteristics of study participants (n = 399) Variable Value Mean age, y (range) 68.5 (24–98) Male-to-female ratio 243:156 Final diagnosis Malignant 253 (63.4) Cholangiocarcinoma 214 (53.6) Gallbladder adenocarcinoma 12 (3.0) Ampullary adenocarcinoma 18 (4.5) Neuroendocrine tumor 2 (0.5) Other cancer (pancreatic, colon, lung) 7 (1.8) Benign 146 (36.6) Choledocholithiasis 52 (13.0) Chronic pancreatitis 13 (3.3) Postsurgical 1 (0.3) IgG-related stricture 6 (1.5) Primary sclerosing cholangitis 3 (0.8) Idiopathic 71 (17.8) Values are n (%) unless otherwise defined. Cellularity In a total of 399 patients, 374 samples yielded adequate cells using the CCM, while 25 samples contained inadequate cells. Additionally, 361 samples yielded adequate cells using the CFM, while 38 samples contained inadequate cells. Among the 253 patients with malignant biliary strictures, 249 samples yielded adequate cells using the CCM, while 4 samples contained inadequate cells. Furthermore 237 samples yielded adequate cells using the CFM, while 16 samples contained inadequate cells. In the 146 patients with benign biliary strictures, 125 samples yielded adequate cells with the CCM, while 21 samples contained inadequate cells. Moreover, 124 samples yielded adequate cells with the CFM, while 22 samples contained inadequate cells. Most samples yielded adequate cells using either the CCM or CFM, with no significant difference in diagnostic yield between methods (93.7% vs. 90.5%, respectively, P = 0.721; Table 2 ). Table 2 Final diagnosis and cellularity Diagnostic yield according to final clinicopathologic diagnosis, n (%) CCM with Pap staining CFM with MARS1 immunostaining P -value Adequate Inadequate Adequate Inadequate Malignant (n = 253) 249 (98.4%) 4 237 (93.7%) 16 0.021 Benign (n = 146) 125 (85.6%) 21 124 (84.9%) 22 0.201 Total (n = 399) 374 (93.7%) 25 361 (90.5%) 38 0.721 CCM, conventional cytologic method; CFM, catheter flushing method; MARS1, methionyl-tRNA synthetase 1. Diagnostic performance The CCM provided the following diagnoses: malignant (90), suspicious for malignancy (100), atypical (104), negative for malignancy (80), and inadequate (25). Among the 90 malignant diagnoses made by the CCM, all were pathologically confirmed, with 85 positive and 5 negative diagnoses by the CFM. Out of the 100 brushings labeled as suspicious for malignancy, 97 were proven to be malignancies, with 89 positive and 11 negative diagnoses by the CFM. Among the 104 brushings diagnosed with atypia, 48 were confirmed to be malignancies, with 35 positive and 13 negative diagnoses by the CFM. Regarding the 80 brushings diagnosed as negative for malignancy by the CCM, 66 were found to be benign, with 14 positive and 51 negative diagnoses by the CFM. Lastly, out of the 25 brushings labeled as nondiagnostic by the CCM, 21 were determined to be benign, with 13 positive and 8 negative diagnoses by the CFM. (Table 3 ) Table 3 Association between brushing cytology results and clinicopathologic diagnosis CCM with Pap staining Final clinicopathologic diagnosis CFM with MARS1 immunostaining Positive Negative Malignancy (n = 90) Malignant (n = 90) 85 5 Benign (n = 0) 0 0 Suspicious of malignancy (n = 100) Malignant (n = 97) 86 11 Benign (n = 3) 3 0 Atypical (n = 104) Malignant (n = 48) 35 13 Benign (n = 56) 15 41 Negative for malignancy (n = 80) Malignant (n = 14) 8 6 Benign (n = 66) 14 51 Nondiagnostic (n = 25) Malignant (n = 4) 0 4 Benign (n = 21) 13 8 Total (n = 399) Malignant (n = 253) 214 39 Benign (n = 146) 45 100 CCM, conventional cytology method; CFM, catheter flushing method. CCM and CFM results along with final clinicopathologic diagnoses are shown in Table 3 . The CFM had significantly higher sensitivity and NPV than the CCM, whereas the CCM had significantly higher specificity and PPV than the CFM (Table 4 ). There was no significant difference between methods in accuracy. If both the CCM and CFM were used together, their combined sensitivity, specificity, PPV, NPV, and accuracy were 94.5%, 69.2%, 87.4%, 84.7%, and 86.7%, respectively. Table 4 Diagnostic performance of the CCM and CFM Sensitivity (%) Specificity (%) PPV (%) NPV (%) Accuracy (%) CCM with Pap staining 75.1 (69.2–80.3) 97.6 (93.1–99.5) 98.4 (95.3–99.5) 66.3 (61.3–71.0) 82.6 (78.4–86.3) CFM with MARS1 immunofluorescence staining 90.3 (85.8–93.7) 63.7 (54.6–72.2) 82.6 (79.0–85.8) 77.5 (69.5–83.8) 81.2 (76.7–85.1) CCM + CFM 94.5 (90.7–97.0) 69.2 (59.4–77.9) 87.4 (83.8–90.3) 84.7 (76.3–90.5) 86.7 (82.6–90.2) P -value < 0.001 < 0.001 < 0.001 0.049 0.608 Values are % (95% confidence interval). CCM, conventional cytology method; CFM, catheter flushing method; PPV, positive predictive value; MARS1, Methionyl-tRNA synthetase 1; NPV, negative predictive value. * P -value for CCM vs. CFM. DISCUSSION We found that the CCM and CFM had similar diagnostic yields and accuracy, whereas the CFM significantly outperformed the CCM in terms of sensitivity and NPV. Thus, the CFM could serve as an additional brush cytology technique for diagnosing indeterminate biliary strictures. One advantage of the CFM is that it is cost-effective. Not only did the CFM have a similar diagnostic yield as the CCM, it did not incur additional costs and only required the additional flushing of medium. Moreover, the addition of the CFM provided more cells for effectively diagnosing the etiology of indeterminate biliary strictures as opposed to the use of the CCM alone. After brush cytology, the cells were bottled in one container for the CCM and two containers with the addition of the CFM. As preparing two containers with one brushing has the same effect as two brushings, the addition of the CFM could save both brushing time and cost. Thus, the CFM could be beneficial to both the patient undergoing ERCP and the physician performing the procedure, as performing brush cytology multiple times during ERCP to obtain more cells not only lengthens the procedure time but also increases the possibility of contamination. Obtaining a larger quantity of cells using the CFM could allow further analyses, such as immunocytochemistry, immunofluorescence staining (e.g., MARS1), or fluorescence in situ hybridization. For instance, in the challenging clinical scenario of primary sclerosing cholangitis (PSC), where no mass is initially present and cytology results are inconclusive, the use of fluorescence in situ hybridization to detect polysomy is effective in identifying patients at higher risk of having or developing malignancy. [ 26 ] Moreover, next-generation sequencing (NGS) has been performed using both brush cytology and biopsy tissue, [ 27 , 28 ] which improves the diagnosis rate of biliary tract cancer. [ 27 , 29 ] When compared with histological specimens, cytological samples often yield high-quality but limited nucleic acid input. [ 28 ] However, one problem with cell blocks is that prolonged fixation in formalin can lead to C > T sequence artifacts. [ 28 ] In a study by Singhi et al., the detection rate of malignant strictures in patients with PSC was enhanced when the gene panel was evaluated using NGS in addition to the existing pathological diagnosis method through brush cytology or biopsy. [ 27 ] Furthermore, in a study by Kamp et al., NGS mutation analysis of brush cytology in patients with PSC identified oncogenic mutations with a high level of sensitivity and specificity, demonstrating its valuable contribution as a supplementary tool. [ 29 ] To achieve more accuracy in tumor genetic analysis, such as through immunocytochemistry, immunofluorescence, and NGS, a larger number of cells from brush cytology is required. Thus, there are greater benefits to using the CFM than performing brush cytology multiple times during ERCP. In addition, the CFM can improve the sensitivity of brush cytology. Given that many biliary tract cancer patients have advanced disease when they are diagnosed and have a high mortality rate, a reliable diagnostic technique is important for starting treatment quickly. [ 30 ] In addition, by increasing the sensitivity of brush cytology during ERCP, it would be less necessary to perform additional invasive examinations such as endoscopic ultrasound with fine needle biopsy, repeat ERCP, or cholangioscopy. If additional diagnostic exams are not required, the risk of associated complications (e.g., bleeding, perforation, pancreatitis) is reduced [ 31 , 32 ] with no additional cost. In conventional smears, cells are spread on a glass slide using a rapid rolling motion with the brush and are then fixed with 95% alcohol for Pap staining. This can be difficult in some cases, as evenly spreading the cells on a slide requires quick movement. However, the washing, cutting, and flushing steps of the CFM are not laborious. Furthermore, compared with conventional smears, the CFM, which involves liquid-based cytology (LBC), could improve diagnostic sensitivity and accuracy. [ 33 ] Indeed, the development of LBC was driven by the need to overcome the limitations of conventional smears, including the challenges of cell clouding and blood contamination. [ 34 ] Several researchers highlight that conventional smear techniques often lead to misdiagnoses due to issues such as inadequate cellularity, artifacts caused by air drying, obscuring material, and excessively thick smears. LBC addresses these limitations by employing collection tubes, preservative fluid, and a semi-automated transfer technique. [ 33 ] Lee et al. demonstrated that LBC has higher sensitivity and accuracy than conventional smears when brush cytology was performed with ERCP. The diagnostic performance of LBC is also comparable to that of forceps biopsies. [ 33 ] Similarly, Chun et al. showed that LBC is equally effective as conventional smears in diagnosing solid pancreatic masses during endoscopic ultrasound-guided fine needle aspiration. In this previous study, there were no significant differences in cytomorphologic characteristics between the CFM and CCM, and the reduced presence of blood in LBC samples resulted in better visibility. [ 35 ] This study has several limitations. First, it had a retrospective design. As the two brush cytology methods employed different staining techniques, this may have affected their diagnostic performance. Differences between ThinPrep and SurePath methods of LBC may also affect diagnostic performance. [ 36 ] Nevertheless, the significant difference in sensitivity between the CCM and CFM indicates that the CFM may be a helpful additional method of brush cytology. It is also encouraging that there was no significant difference in the accuracy of the two methods. Second, MARS1 immunofluorescence staining is not yet a standard method of LBC, and its reliability may be questionable. However, as previously demonstrated, MARS1 immunofluorescence staining shows similar results as conventional Pap staining. [ 21 ] In addition, LBC has been shown to have better diagnostic performance than conventional smear and biopsy methods. [ 33 ] Despite these limitations, the present study demonstrates that the CFM can help increase the sensitivity of diagnosing indeterminate biliary strictures. CONCLUSION In conclusion, the high sensitivity and similar accuracy of the CFM compared to the CCM indicates that the CFM could be used as an additional brush cytology method. Further prospective studies are needed to validate these findings. Declarations AUTHOR CONTRIBUTIONS SIJ had full access to all study data and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: SIJ and JHC Acquisition, analysis, or interpretation of data: MJS, JHN, SJ, THL, JHC, CIK, DUK, and SIJ Drafting of the manuscript: MJS and SIJ Critical revision of the manuscript for important intellectual content: MJS and SIJ Statistical analysis: MJS Obtained funding: None Administrative, technical, or material support: JHN, SJ, THL, JHC, CIK, DUK, and SIJ Study supervision: SIJ and JHC CONFLICT OF INTEREST DISCLOSURE : None reported. ACKNOWLEDGEMENT FUNDING/SUPPORT This study was supported by a clinical research grant from Koran Pancreatobiliary Association in 2023 (S.M.J), NRF-2018M3A9F7062524(S.I.J) from the National Research Foundation, MSIT of Korea, and Korea Gastrointestinal Endoscopy Research Foundation Pharmaceutical Research Fund (S.I.J). References Pereira SP, Goodchild G, Webster GJM. The endoscopist and malignant and non-malignant biliary obstruction. Biochim Biophys Acta Mol Basis Dis. 2018;1864:1478–1483. https://doi.org/10.1016/j.bbadis.2017.09.013 . Sun B, Moon JH, Cai Q, et al. Review article: Asia-Pacific consensus recommendations on endoscopic tissue acquisition for biliary strictures. Aliment Pharmacol Ther. 2018;48:138–151. https://doi.org/10.1111/apt.14811 . Ponchon T, Gagnon P, Berger F, et al. Value of endobiliary brush cytology and biopsies for the diagnosis of malignant bile duct stenosis: results of a prospective study. Gastrointestinal endoscopy. 1995;42:565–572. Glasbrenner B, Ardan M, Boeck W, et al. Prospective evaluation of brush cytology of biliary strictures during endoscopic retrograde cholangiopancreatography. Endoscopy. 1999;31:712–717. De Bellis M, Sherman S, Fogel EL, et al. Tissue sampling at ERCP in suspected malignant biliary strictures (Part 1). Gastrointestinal endoscopy. 2002;56:552–561. Jin YH, Kim SH, Park CK. Diagnostic criteria for malignancy in bile cytology and its usefulness. J Korean Med Sci. 1999;14:643–647. https://doi.org/10.3346/jkms.1999.14.6.643 . Harada H, Sasaki T, Yamamoto N, et al. Assessment of endoscopic aspiration cytology and endoscopic retrograde cholangio-pancreatography in patients with cancer of the hepato-biliary tract. Part II. Gastroenterol Jpn. 1977;12:59–64. https://doi.org/10.1007/bf02774003 . Cobb CJ, Floyd WN, Jr. Usefulness of bile cytology in the diagnostic management of patients with biliary tract obstruction. Acta Cytol. 1985;29:93–100. Leung JW, Sung JY, Chung SC, et al. Endoscopic scraping biopsy of malignant biliary strictures. Gastrointest Endosc. 1989;35:65–66. https://doi.org/10.1016/s0016-5107(89)72696-1 . Foutch PG, Harlan JR, Kerr D, et al. Wire-guided brush cytology: a new endoscopic method for diagnosis of bile duct cancer. Gastrointest Endosc. 1989;35:243–247. https://doi.org/10.1016/s0016-5107(89)72767-x . Foutch PG, Kerr DM, Harlan JR, et al. A prospective, controlled analysis of endoscopic cytotechniques for diagnosis of malignant biliary strictures. Am J Gastroenterol. 1991;86:577–580. Chang L, French S, Hierro M, et al. A prospective study comparing endobiliary biopsy, brush and aspiration cytology during ERCP in diagnosing biliary obstructive lesions. Am J Gastroenterol. 1992;87:1282. Farrell RJ, Jain AK, Brandwein SL, et al. The combination of stricture dilation, endoscopic needle aspiration, and biliary brushings significantly improves diagnostic yield from malignant bile duct strictures. Gastrointest Endosc. 2001;54:587–594. https://doi.org/10.1067/mge.2001.118715 . de Bellis M, Fogel EL, Sherman S, et al. Influence of stricture dilation and repeat brushing on the cancer detection rate of brush cytology in the evaluation of malignant biliary obstruction. Gastrointest Endosc. 2003;58:176–182. https://doi.org/10.1067/mge.2003.345 . Fogel EL, deBellis M, McHenry L, et al. Effectiveness of a new long cytology brush in the evaluation of malignant biliary obstruction: a prospective study. Gastrointest Endosc. 2006;63:71–77. https://doi.org/10.1016/j.gie.2005.08.039 . Dumonceau JM, Macias Gomez C, Casco C, et al. Grasp or brush for biliary sampling at endoscopic retrograde cholangiography? A blinded randomized controlled trial. Am J Gastroenterol. 2008;103:333–340. https://doi.org/10.1111/j.1572-0241.2007.01543.x . Sugimoto S, Matsubayashi H, Kimura H, et al. Diagnosis of bile duct cancer by bile cytology: usefulness of post-brushing biliary lavage fluid. Endosc Int Open. 2015;3:E323-328. https://doi.org/10.1055/s-0034-1391666 . Wakasa T, Inayama K, Honda T, et al. Brushing cytology of the biliary tract: bile juice from the ERCP sheath tube provides cell-rich smear samples. Acta Cytol. 2014;58:398–405. https://doi.org/10.1159/000364852 . Nur AM, Salim M, Boerner S, et al. High Diagnostic Yield of Endoscopic Retrograde Cholangiopancreatography Brush Cytology for Indeterminate Strictures. J Can Assoc Gastroenterol. 2022;5:234–239. https://doi.org/10.1093/jcag/gwac011 . Amog-Jones GF, Chandra S, Jensen C, et al. Including the Sheath Rinse to Improve Cellular Yield in Biliary Brushing Cytology. Clin Endosc. 2017;50:614–616. https://doi.org/10.5946/ce.2017.113 . Jang SI, Nahm JH, Kwon NH, et al. Clinical utility of methionyl-tRNA synthetase 1 immunostaining in cytologic brushings of indeterminate biliary strictures: a multicenter prospective study. Gastrointest Endosc. 2021;94:733–741 e734. https://doi.org/10.1016/j.gie.2021.04.026 . Jang SI, Kwon NH, Lim BJ, et al. New staining method using methionyl-tRNA synthetase 1 antibody for brushing cytology of bile duct cancer. Gastrointest Endosc. 2020;92:310–319 e316. https://doi.org/10.1016/j.gie.2019.12.017 . Pitman MB, Layfield LJ. Guidelines for pancreaticobiliary cytology from the Papanicolaou Society of Cytopathology: A review. Cancer Cytopathology. 2014;122:399–411. https://doi.org/10.1002/cncy.21427 . Luna LEM, Kipp B, Halling KC, et al. Advanced cytologic techniques for the detection of malignant pancreatobiliary strictures. Gastroenterology. 2006;131:1064–1072. Khashab MA, Fockens P, Al-Haddad MA. Utility of EUS in patients with indeterminate biliary strictures and suspected extrahepatic cholangiocarcinoma (with videos). Gastrointestinal endoscopy. 2012;76:1024–1033. Barr Fritcher EG, Voss JS, Jenkins SM, et al. Primary sclerosing cholangitis with equivocal cytology: fluorescence in situ hybridization and serum CA 19 – 9 predict risk of malignancy. Cancer Cytopathol. 2013;121:708–717. https://doi.org/10.1002/cncy.21331 . Singhi AD, Nikiforova MN, Chennat J, et al. Integrating next-generation sequencing to endoscopic retrograde cholangiopancreatography (ERCP)-obtained biliary specimens improves the detection and management of patients with malignant bile duct strictures. Gut. 2020;69:52–61. https://doi.org/10.1136/gutjnl-2018-317817 . Pisapia P, Pepe F, Sgariglia R, et al. Next generation sequencing in cytology. Cytopathology. 2021;32:588–595. https://doi.org/10.1111/cyt.12974 . Kamp E, Dinjens WNM, van Velthuysen MF, et al. Next-generation sequencing mutation analysis on biliary brush cytology for differentiation of benign and malignant strictures in primary sclerosing cholangitis. Gastrointest Endosc. 2023;97:456–465.e456. https://doi.org/10.1016/j.gie.2022.10.014 . Kim BW, Oh CM, Choi HY, et al. Incidence and Overall Survival of Biliary Tract Cancers in South Korea from 2006 to 2015: Using the National Health Information Database. Gut Liver. 2019;13:104–113. https://doi.org/10.5009/gnl18105 . Anderson MA, Fisher L, Jain R, et al. Complications of ERCP. Gastrointest Endosc. 2012;75:467–473. https://doi.org/10.1016/j.gie.2011.07.010 . Jenssen C, Alvarez-Sánchez MV, Napoléon B, et al. Diagnostic endoscopic ultrasonography: assessment of safety and prevention of complications. World J Gastroenterol. 2012;18:4659–4676. https://doi.org/10.3748/wjg.v18.i34.4659 . Lee MW, Paik WH, Lee SH, et al. Usefulness of Liquid-Based Cytology in Diagnosing Biliary Tract Cancer Compared to Conventional Smear and Forceps Biopsy. Dig Dis Sci. 2022. https://doi.org/10.1007/s10620-022-07535-3 . Linder J. Recent advances in thin-layer cytology. Diagn Cytopathol. 1998;18:24–32. https://doi.org/10.1002/(sici)1097-0339(199801)18:13.0.co;2-u . Chun JW, Lee K, Lee SH, et al. Comparison of liquid-based cytology with conventional smear cytology for EUS-guided FNA of solid pancreatic masses: a prospective randomized noninferiority study. Gastrointest Endosc. 2020;91:837–846 e831. https://doi.org/10.1016/j.gie.2019.11.018 . Wright PK, Marshall J, Desai M. Comparison of SurePath® and ThinPrep® liquid-based cervical cytology using positive predictive value, atypical predictive value and total predictive value as performance indicators. Cytopathology. 2010;21:374–378. https://doi.org/10.1111/j.1365-2303.2010.00772.x . Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3911988","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":271449632,"identity":"2b817e1f-faf5-42a5-9f14-e1a3e0010804","order_by":0,"name":"Sung Ill Jang","email":"","orcid":"","institution":"Yonsei University College of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Sung","middleName":"Ill","lastName":"Jang","suffix":""},{"id":271449633,"identity":"298a8e2e-771f-4992-94a8-3d8ad710b022","order_by":1,"name":"Min Je Sung","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxElEQVRIiWNgGAWjYFCCg+0/JHhsGAwgvARitBxukLCQSSNJC3uDRIXNYRK06DYebDC4kXNe3pz9AOOHHwxp+QS1mB042JA448xtw509CcySPQw5lg3EaDks2XM7weBAAoM0A0OFATG2NDb//XcuweD8A+bfxGppZpDgOZBgcCOBDWhLDlFa2oBakg033HjYZtljkEaElhvHnwG12MkbnE8+fONHRTJhLQwSB2AsxgYGBiI0MDDwNxCjahSMglEwCkY0AADpaUC/gz+nbAAAAABJRU5ErkJggg==","orcid":"","institution":"CHA Bundang Medical Center, CHA University","correspondingAuthor":true,"prefix":"","firstName":"Min","middleName":"Je","lastName":"Sung","suffix":""},{"id":271449634,"identity":"b83019bb-161e-412a-92fa-62582f65d95d","order_by":2,"name":"Ji Hae Nahm","email":"","orcid":"","institution":"Yonsei University College of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Ji","middleName":"Hae","lastName":"Nahm","suffix":""},{"id":271449635,"identity":"eab94ce4-8eb3-491f-8788-b87e7f717d6a","order_by":3,"name":"Seok Jeong","email":"","orcid":"","institution":"Inha University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Seok","middleName":"","lastName":"Jeong","suffix":""},{"id":271449636,"identity":"90a1c8a2-c9c6-4a57-a6c1-4d3ab82613d7","order_by":4,"name":"Tae Hoon Lee","email":"","orcid":"","institution":"Soonchunhyang University College of Medicine, Cheonan Hospital","correspondingAuthor":false,"prefix":"","firstName":"Tae","middleName":"Hoon","lastName":"Lee","suffix":""},{"id":271449637,"identity":"89f61342-126e-4a3d-8df3-2a392ca63be9","order_by":5,"name":"Chang-Il Kwon","email":"","orcid":"","institution":"CHA Bundang Medical Center, CHA University","correspondingAuthor":false,"prefix":"","firstName":"Chang-Il","middleName":"","lastName":"Kwon","suffix":""},{"id":271449638,"identity":"49751db7-6d6e-44ea-90a3-c540af035da5","order_by":6,"name":"Dong Uk Kim","email":"","orcid":"","institution":"Pusan National University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Dong","middleName":"Uk","lastName":"Kim","suffix":""},{"id":271449639,"identity":"73b2cfb0-68c0-4851-8e6f-f4634f4ca6c5","order_by":7,"name":"See Young Lee","email":"","orcid":"","institution":"Yonsei University College of Medicine","correspondingAuthor":false,"prefix":"","firstName":"See","middleName":"Young","lastName":"Lee","suffix":""},{"id":271449640,"identity":"8a9fe091-4918-4d61-b2d2-5e6a3c5acd0c","order_by":8,"name":"Jae Hee Cho","email":"","orcid":"","institution":"Yonsei University College of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Jae","middleName":"Hee","lastName":"Cho","suffix":""}],"badges":[],"createdAt":"2024-01-30 23:59:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3911988/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3911988/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":50814328,"identity":"f8392f89-c036-47d2-bf4d-ef1d0fbc8519","added_by":"auto","created_at":"2024-02-07 19:37:15","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":9252887,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDiagnostic procedures.\u003c/strong\u003e ERCP was used to collect bile duct brushings by making five to eight passes over the lesions (A–B). For CCM, the brush was washed with Roswell Park Memorial Institute-1640 medium in a container (C–E). For CFM, the brush was cut at the wire using surgical scissors into a container with preservative (F). After removal of the wire, a 10-mL syringe with normal saline was used to flush residual sample from the catheter sheath into the container (G–I).\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-3911988/v1/1cda82d3fc277d3e85470f4e.png"},{"id":50814329,"identity":"a9cd93b6-0028-46e6-8b0d-aae5d85bd81c","added_by":"auto","created_at":"2024-02-07 19:37:15","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":6284546,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAdequate and inadequate samples in the CCM with Pap staining. \u003c/strong\u003eThree examples of high cellularity (A; original magnification, B, C; original magnification 400×). Three examples of low cellularity (D; original magnification, E, F; original magnification 400×).\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-3911988/v1/cfcc6cf91072714e606be82d.png"},{"id":50814327,"identity":"b726add0-a464-4a7c-b1ec-8180a2acd1c5","added_by":"auto","created_at":"2024-02-07 19:37:14","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":4203935,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAdequate and inadequate samples in the CFM with immunofluorescence staining for MARS1. \u003c/strong\u003eThree examples of high cellularity (A; original magnification, B, C; original magnification 400×). Three examples of low cellularity (D; original magnification, E, F; original magnification 400×).\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-3911988/v1/1d8727048c6c4975c6be9974.png"},{"id":60477851,"identity":"29b36315-0de9-4303-8e2f-0b3a53220c59","added_by":"auto","created_at":"2024-07-17 08:07:29","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":18980754,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3911988/v1/c797147a-db8b-4761-97cc-d2a221332e4b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The catheter flushing method increases the diagnostic yield of brushing cytology for biliary strictures","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eBiliary strictures can occur in the biliary tract due to a variety of etiologies, ranging from benign conditions to malignancies. [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] Despite the availability of various imaging modalities such as abdominal ultrasound, endoscopic ultrasound, computed tomography (CT), and magnetic resonance imaging, it is often difficult to determine the etiology of biliary strictures by imaging alone. Thus, pathologic confirmation is necessary for accurately diagnosing indeterminate biliary strictures, especially with suspicion of biliary tract cancer. Brush cytology is routinely performed during endoscopic retrograde cholangiopancreatography (ERCP) to determine the malignancy of biliary strictures. [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] However, the sensitivity of endoscopic brush cytology is as low as 20\u0026ndash;40%. [\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] Some researchers propose that the low sensitivity of brush cytology is mainly due to inadequate cellular sampling, although a false-negative diagnosis can occur when there is insufficient cellularity regardless of the sampling technique used. [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eTo improve the diagnostic yield, various endoscopic techniques have been proposed to diagnose cancer using cytology, including bile aspiration and examination of cells in the side flaps of biliary stents. [\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] Foutch et al. were the first to describe endobiliary brushing over a guidewire, [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] with later studies reporting that brush cytology is superior to simple aspiration of bile for the diagnosis of malignant strictures. [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] Specifically, Foutch et al. found that the sensitivity of brush cytology (33%) was higher than that of simple aspiration from bile (6%). To further increase the cancer detection rate of brush cytology, both dilatation of the stricture and endoscopic needle aspiration have been performed together. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] However, one study reports that using a pneumatic balloon or graduated dilating catheter does not increase the detection rate of brush cytology, whereas repeat brushing increases the diagnostic yield. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] Furthermore, although using a longer cytology brush enhances cellularity, it does not improve the cancer detection rate compared with a standard brush. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] There has also been an attempt to sample bile duct strictures using dedicated basket grasping instead of brushing. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] In addition, post-brushing biliary lavage fluid cytology was found to be superior to bile aspiration or brush smear. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eRecently, multiple studies show that flushing the catheter sheath after the brush is removed increases the yield of ERCP biliary brush cytology and thereby improves diagnostic performance. [\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] Wakasa et al. found that the combination of conventional smear with brush washing and flushing the sheath tube contents increases diagnostic accuracy (78.7%) compared with conventional smear procedures alone (68.8%). [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] Nur et al. report that ERCP brush cytology performed together with cutting the cytology brush and flushing the catheter sheath produces a high diagnostic yield (84%). [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] Moreover, Amog-Jones et al. found that the combination of brushing and sheath tube rinsing produced moderate-to-high cellularity in 10 of 13 (77%) specimens. [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] However, a clinically confirmative and effective method to increase the diagnostic yield of brush cytology has not been established.\u003c/p\u003e \u003cp\u003eHere, we compared the diagnostic performance of the catheter flushing method (CFM) versus the conventional cytologic method (CCM) during ERCP in patients with indeterminate biliary strictures.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design\u003c/h2\u003e \u003cp\u003eThis retrospective study was conducted at six tertiary medical centers. The study protocol was approved by the institutional review boards at all six facilities (3-2020-0005). The primary outcome was diagnostic performance in terms of diagnostic yield, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy. The study data were accessible to all authors, each of whom reviewed and approved the final version of this manuscript.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003ePatient selection\u003c/h2\u003e \u003cp\u003eInclusion criteria were as follows: biliary stricture confirmed by imaging (CT, magnetic resonance imaging, or positron emission tomography), brush cytology, and intraductal biopsy sampling by ERCP or surgical specimens; age\u0026thinsp;\u0026ge;\u0026thinsp;19 years; and no prior procedures involving the papilla. Exclusion criteria were as follows: age\u0026thinsp;\u0026le;\u0026thinsp;18 years, pregnancy, intellectual disability, sensitivity to contrast agent, acute cholangitis, and past pancreatobiliary surgery.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eDiagnostic procedures\u003c/h2\u003e \u003cp\u003eERCP was used to collect bile duct brushings (GRBH-230-3-3.5 brush; Wilson-Cook Medical Inc, Winston-Salem, NC, USA) by making five to eight passes over the lesions (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA, B). To prepare the CCM sample, the brush was washed in a container filled with Roswell Park Memorial Institute-1640 medium (Gibco BRL, Thermo Fisher Scientific, Waltham, MA, USA) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC\u0026ndash;E). To prepare the CFM sample, the brush was cut at the wire using surgical scissors into a second container with preservative (Pro-Fixx; Lerner Laboratories, Pittsburgh, PA, USA) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eF). After removing the wire, a 10-mL syringe with normal saline was used to flush residual sample from the catheter sheath into the second container (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eG\u0026ndash;I), which was then wrapped in aluminum foil and stored at 20\u0026deg;C. [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] After collection, samples were immediately transferred to the cytology laboratory for liquid-based ThinPrep (Cytyc Corp, Marlborough, MA, USA) slide preparation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eAssessment of cellularity\u003c/h2\u003e \u003cp\u003eQuantitative analysis of cellularity, defined as the presence of cellular material, was performed for each sample. Cellularity was evaluated by assigning a grade based on the number of epithelial cells observed on each slide. Grade 0 indicates insufficient epithelial cells for interpretation (\u0026lt;\u0026thinsp;20% of slide study area covered by epithelial cells); grade 1 indicates limited cellular material (20\u0026ndash;50% of slide study area covered by epithelial cells); grade 2 indicates good cellularity (50\u0026ndash;80% of slide study area covered by epithelial cells); and grade 3 indicates cellularity (\u0026gt;\u0026thinsp;80% of slide study area covered by epithelial cells). Grades 0 and 1 were considered inadequate due to the limited amount of material available for interpretation, whereas grades 2 and 3 were considered adequate.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eImmunofluorescence staining\u003c/h2\u003e \u003cp\u003eFor methionyl-transfer RNA synthetase 1 (MARS1) immunofluorescence staining of CFM samples, liquid-based ThinPrep slides were permeabilized in 0.3% phosphate-buffered saline containing Tween (Sigma-Aldrich, St. Louis, MO, USA) for 30 min. After two to three washes with Tris-buffered saline solution including 0.5% Tween 20 (TBS-T), slides were rinsed with distilled water and blocked for 20 min at room temperature with 3% goat serum. Slides were then incubated for 1 h at 37\u0026deg;C with anti- MARS1 primary antibody (1:100; BICBIO, Suwon, South Korea). After two to three washes with TBS-T, slides were incubated with secondary antibody (anti-mouse antibody Alexa Fluor 488 conjugate, 1:300; Thermo Fisher Scientific, Eugene, OR, USA) for 30 min at room temperature. The final two to three washes with TBS-T were followed by 4\u0026prime;,6-diamidino-2-phenylindole (Molecular Probes, Thermo Fisher Scientific) counterstaining. [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eInterpretation of sample staining\u003c/h2\u003e \u003cp\u003eThe categories were dichotomized into adequate (cellularity grade 2 or 3) and inadequate (cellularity grade 0 or 1) groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), and diagnostic yield was defined as the number of brush samples in the adequate group. Three pathologists (JHN, JMK, and HDC) blinded to clinical data and Papanicolaou (Pap) staining results independently examined all cellularity of brush samples.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eBrush cytologic specimens were classified into six categories: nondiagnostic, negative for malignancy, atypical, neoplastic (benign or other), suspicious for malignancy, and malignancy. [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] The 'neoplastic (benign or other)' category is typically assigned to cases suspected of being pancreatic neoplasms, which include pancreatic neuroendocrine tumors, solid pseudopapillary neoplasms, intraductal papillary neoplasms, and mucinous cystic neoplasms. Consequently, such cases were not included in this study.\u003c/p\u003e \u003cp\u003eMARS1 immunofluorescence-stained slides were assessed in conjunction with positive (TKF-1 cells) and negative (NIH 3T3 cells) control slides. A fluorescent microscope (BX53; Olympus Corp, Tokyo, Japan) was used to view entire fields of cytologic slides at a magnification of at least 200\u0026times;. Positive MARS1 staining was defined as more than one cell cluster with a high immunofluorescence signal in the cytoplasm or plasma membrane (i.e., fluorescence intensity similar to or stronger than that of positive control cells) at a magnification of at least 200\u0026times;. Weak or ambiguous staining of epithelial cells was considered negative. Three pathologists blinded to clinical data and Papanicolaou (Pap) staining results independently examined all MARS1 immunofluorescence-stained cytologic tissues. Any discrepancy was resolved through collaborative examination of specimens. [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eClinicopathologic diagnoses\u003c/h2\u003e \u003cp\u003eFor analytic purposes, based on CCM Pap staining, the malignant and suspicious malignancy categories were combined into a malignant subset, and the atypical and negative malignancy categories were combined into a nonmalignant subset. Suspicious for malignancy is an extremely high-risk cytologic diagnostic. [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] MARS1 immunofluorescence staining was considered positive or negative, and indeterminate biliary strictures were defined as those whose etiology remained unknown after ultrasound, CT, ERCP, or cytologic assessment. [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] Brush cytology, intraductal biopsy sampling, biopsy sampling of metastatic lesions, and/or surgical specimen findings were used to determine the final clinicopathologic diagnosis. If a pathologic diagnosis could not be made, the final diagnosis relied on clinical and radiologic data collected during at least a 12-month period of follow-up. In summary, malignant biliary strictures were confirmed pathologically using brush cytology, intraductal biopsy sampling, biopsy sampling of metastatic lesions, and/or surgical specimens. Benign biliary strictures were diagnosed clinically or radiologically with at least 12 months of clinical follow-up.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eThe diagnostic yield was analyzed using the χ2 test. The McNemar test was used to assess sensitivity, specificity, PPV, NPV, and accuracy with a \u003cem\u003eP\u003c/em\u003e-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicating statistical significance. The Cochran-Mantel-Haenszel test and logistic regression with the generalized estimating equation (extended McNemar approach) were used to compare diagnostic performance. SPSS version 27 for Windows software (IBM Inc, Armonk, NY, USA) was used for statistical analysis.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003ePatient characteristics\u003c/h2\u003e \u003cp\u003eIn total, 399 patients with biliary stricture were included in the study. Mean patient age was 68.5 years, and there were more male than female patients (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Malignancy was detected in 253 biliary strictures (63.4%), the most common of which was cholangiocarcinoma (n\u0026thinsp;=\u0026thinsp;214, 53.6%). The other 146 biliary strictures (36.6%) were considered benign and were most commonly considered idiopathic (n\u0026thinsp;=\u0026thinsp;71, 17.8%).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCharacteristics of study participants (n\u0026thinsp;=\u0026thinsp;399)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eValue\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean age, y (range)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68.5 (24\u0026ndash;98)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale-to-female ratio\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e243:156\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFinal diagnosis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMalignant\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e253 (63.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCholangiocarcinoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e214 (53.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGallbladder adenocarcinoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12 (3.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAmpullary adenocarcinoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18 (4.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNeuroendocrine tumor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (0.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther cancer (pancreatic, colon, lung)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (1.8)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBenign\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e146 (36.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCholedocholithiasis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e52 (13.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChronic pancreatitis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13 (3.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePostsurgical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (0.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIgG-related stricture\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6 (1.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePrimary sclerosing cholangitis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (0.8)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIdiopathic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e71 (17.8)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eValues are n (%) unless otherwise defined.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eCellularity\u003c/h2\u003e \u003cp\u003eIn a total of 399 patients, 374 samples yielded adequate cells using the CCM, while 25 samples contained inadequate cells. Additionally, 361 samples yielded adequate cells using the CFM, while 38 samples contained inadequate cells. Among the 253 patients with malignant biliary strictures, 249 samples yielded adequate cells using the CCM, while 4 samples contained inadequate cells. Furthermore 237 samples yielded adequate cells using the CFM, while 16 samples contained inadequate cells. In the 146 patients with benign biliary strictures, 125 samples yielded adequate cells with the CCM, while 21 samples contained inadequate cells. Moreover, 124 samples yielded adequate cells with the CFM, while 22 samples contained inadequate cells. Most samples yielded adequate cells using either the CCM or CFM, with no significant difference in diagnostic yield between methods (93.7% vs. 90.5%, respectively, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.721; Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eFinal diagnosis and cellularity\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eDiagnostic yield\u003c/p\u003e \u003cp\u003eaccording to final clinicopathologic diagnosis, n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eCCM with Pap staining\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eCFM with MARS1 immunostaining\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAdequate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eInadequate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAdequate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eInadequate\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMalignant (n\u0026thinsp;=\u0026thinsp;253)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e249 (98.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e237 (93.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.021\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBenign (n\u0026thinsp;=\u0026thinsp;146)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e125 (85.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e124 (84.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.201\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal (n\u0026thinsp;=\u0026thinsp;399)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e374 (93.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e361 (90.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.721\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003eCCM, conventional cytologic method; CFM, catheter flushing method; MARS1, methionyl-tRNA synthetase 1.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eDiagnostic performance\u003c/h2\u003e \u003cp\u003e The CCM provided the following diagnoses: malignant (90), suspicious for malignancy (100), atypical (104), negative for malignancy (80), and inadequate (25). Among the 90 malignant diagnoses made by the CCM, all were pathologically confirmed, with 85 positive and 5 negative diagnoses by the CFM. Out of the 100 brushings labeled as suspicious for malignancy, 97 were proven to be malignancies, with 89 positive and 11 negative diagnoses by the CFM. Among the 104 brushings diagnosed with atypia, 48 were confirmed to be malignancies, with 35 positive and 13 negative diagnoses by the CFM. Regarding the 80 brushings diagnosed as negative for malignancy by the CCM, 66 were found to be benign, with 14 positive and 51 negative diagnoses by the CFM. Lastly, out of the 25 brushings labeled as nondiagnostic by the CCM, 21 were determined to be benign, with 13 positive and 8 negative diagnoses by the CFM. (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAssociation between brushing cytology results and clinicopathologic diagnosis\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCCM with Pap staining\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eFinal clinicopathologic diagnosis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eCFM with MARS1 immunostaining\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePositive\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNegative\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eMalignancy (n\u0026thinsp;=\u0026thinsp;90)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMalignant (n\u0026thinsp;=\u0026thinsp;90)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBenign (n\u0026thinsp;=\u0026thinsp;0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSuspicious of malignancy (n\u0026thinsp;=\u0026thinsp;100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMalignant (n\u0026thinsp;=\u0026thinsp;97)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBenign (n\u0026thinsp;=\u0026thinsp;3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eAtypical (n\u0026thinsp;=\u0026thinsp;104)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMalignant (n\u0026thinsp;=\u0026thinsp;48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBenign (n\u0026thinsp;=\u0026thinsp;56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eNegative for malignancy (n\u0026thinsp;=\u0026thinsp;80)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMalignant (n\u0026thinsp;=\u0026thinsp;14)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBenign (n\u0026thinsp;=\u0026thinsp;66)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eNondiagnostic (n\u0026thinsp;=\u0026thinsp;25)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMalignant (n\u0026thinsp;=\u0026thinsp;4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBenign (n\u0026thinsp;=\u0026thinsp;21)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTotal (n\u0026thinsp;=\u0026thinsp;399)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMalignant (n\u0026thinsp;=\u0026thinsp;253)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e214\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBenign (n\u0026thinsp;=\u0026thinsp;146)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eCCM, conventional cytology method; CFM, catheter flushing method.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eCCM and CFM results along with final clinicopathologic diagnoses are shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The CFM had significantly higher sensitivity and NPV than the CCM, whereas the CCM had significantly higher specificity and PPV than the CFM (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). There was no significant difference between methods in accuracy. If both the CCM and CFM were used together, their combined sensitivity, specificity, PPV, NPV, and accuracy were 94.5%, 69.2%, 87.4%, 84.7%, and 86.7%, respectively.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDiagnostic performance of the CCM and CFM\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSensitivity (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSpecificity (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePPV (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNPV (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAccuracy (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCCM with Pap staining\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e75.1 (69.2\u0026ndash;80.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e97.6 (93.1\u0026ndash;99.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e98.4 (95.3\u0026ndash;99.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e66.3 (61.3\u0026ndash;71.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e82.6 (78.4\u0026ndash;86.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCFM with MARS1 immunofluorescence staining\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e90.3 (85.8\u0026ndash;93.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e63.7 (54.6\u0026ndash;72.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e82.6 (79.0\u0026ndash;85.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e77.5 (69.5\u0026ndash;83.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e81.2 (76.7\u0026ndash;85.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCCM\u0026thinsp;+\u0026thinsp;CFM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e94.5 (90.7\u0026ndash;97.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e69.2 (59.4\u0026ndash;77.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e87.4 (83.8\u0026ndash;90.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e84.7 (76.3\u0026ndash;90.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e86.7 (82.6\u0026ndash;90.2)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.049\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.608\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eValues are % (95% confidence interval).\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eCCM, conventional cytology method; CFM, catheter flushing method; PPV, positive predictive value; MARS1, Methionyl-tRNA synthetase 1; NPV, negative predictive value.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003e*\u003cem\u003eP\u003c/em\u003e-value for CCM vs. CFM.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eWe found that the CCM and CFM had similar diagnostic yields and accuracy, whereas the CFM significantly outperformed the CCM in terms of sensitivity and NPV. Thus, the CFM could serve as an additional brush cytology technique for diagnosing indeterminate biliary strictures.\u003c/p\u003e \u003cp\u003eOne advantage of the CFM is that it is cost-effective. Not only did the CFM have a similar diagnostic yield as the CCM, it did not incur additional costs and only required the additional flushing of medium. Moreover, the addition of the CFM provided more cells for effectively diagnosing the etiology of indeterminate biliary strictures as opposed to the use of the CCM alone. After brush cytology, the cells were bottled in one container for the CCM and two containers with the addition of the CFM. As preparing two containers with one brushing has the same effect as two brushings, the addition of the CFM could save both brushing time and cost. Thus, the CFM could be beneficial to both the patient undergoing ERCP and the physician performing the procedure, as performing brush cytology multiple times during ERCP to obtain more cells not only lengthens the procedure time but also increases the possibility of contamination.\u003c/p\u003e \u003cp\u003eObtaining a larger quantity of cells using the CFM could allow further analyses, such as immunocytochemistry, immunofluorescence staining (e.g., MARS1), or fluorescence \u003cem\u003ein situ\u003c/em\u003e hybridization. For instance, in the challenging clinical scenario of primary sclerosing cholangitis (PSC), where no mass is initially present and cytology results are inconclusive, the use of fluorescence \u003cem\u003ein situ\u003c/em\u003e hybridization to detect polysomy is effective in identifying patients at higher risk of having or developing malignancy. [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] Moreover, next-generation sequencing (NGS) has been performed using both brush cytology and biopsy tissue, [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] which improves the diagnosis rate of biliary tract cancer. [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] When compared with histological specimens, cytological samples often yield high-quality but limited nucleic acid input. [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] However, one problem with cell blocks is that prolonged fixation in formalin can lead to C\u0026thinsp;\u0026gt;\u0026thinsp;T sequence artifacts. [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] In a study by Singhi et al., the detection rate of malignant strictures in patients with PSC was enhanced when the gene panel was evaluated using NGS in addition to the existing pathological diagnosis method through brush cytology or biopsy. [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] Furthermore, in a study by Kamp et al., NGS mutation analysis of brush cytology in patients with PSC identified oncogenic mutations with a high level of sensitivity and specificity, demonstrating its valuable contribution as a supplementary tool. [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] To achieve more accuracy in tumor genetic analysis, such as through immunocytochemistry, immunofluorescence, and NGS, a larger number of cells from brush cytology is required. Thus, there are greater benefits to using the CFM than performing brush cytology multiple times during ERCP.\u003c/p\u003e \u003cp\u003eIn addition, the CFM can improve the sensitivity of brush cytology. Given that many biliary tract cancer patients have advanced disease when they are diagnosed and have a high mortality rate, a reliable diagnostic technique is important for starting treatment quickly. [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] In addition, by increasing the sensitivity of brush cytology during ERCP, it would be less necessary to perform additional invasive examinations such as endoscopic ultrasound with fine needle biopsy, repeat ERCP, or cholangioscopy. If additional diagnostic exams are not required, the risk of associated complications (e.g., bleeding, perforation, pancreatitis) is reduced [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] with no additional cost.\u003c/p\u003e \u003cp\u003eIn conventional smears, cells are spread on a glass slide using a rapid rolling motion with the brush and are then fixed with 95% alcohol for Pap staining. This can be difficult in some cases, as evenly spreading the cells on a slide requires quick movement. However, the washing, cutting, and flushing steps of the CFM are not laborious. Furthermore, compared with conventional smears, the CFM, which involves liquid-based cytology (LBC), could improve diagnostic sensitivity and accuracy. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] Indeed, the development of LBC was driven by the need to overcome the limitations of conventional smears, including the challenges of cell clouding and blood contamination. [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e] Several researchers highlight that conventional smear techniques often lead to misdiagnoses due to issues such as inadequate cellularity, artifacts caused by air drying, obscuring material, and excessively thick smears. LBC addresses these limitations by employing collection tubes, preservative fluid, and a semi-automated transfer technique. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] Lee et al. demonstrated that LBC has higher sensitivity and accuracy than conventional smears when brush cytology was performed with ERCP. The diagnostic performance of LBC is also comparable to that of forceps biopsies. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] Similarly, Chun et al. showed that LBC is equally effective as conventional smears in diagnosing solid pancreatic masses during endoscopic ultrasound-guided fine needle aspiration. In this previous study, there were no significant differences in cytomorphologic characteristics between the CFM and CCM, and the reduced presence of blood in LBC samples resulted in better visibility. [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eThis study has several limitations. First, it had a retrospective design. As the two brush cytology methods employed different staining techniques, this may have affected their diagnostic performance. Differences between ThinPrep and SurePath methods of LBC may also affect diagnostic performance. [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e] Nevertheless, the significant difference in sensitivity between the CCM and CFM indicates that the CFM may be a helpful additional method of brush cytology. It is also encouraging that there was no significant difference in the accuracy of the two methods. Second, MARS1 immunofluorescence staining is not yet a standard method of LBC, and its reliability may be questionable. However, as previously demonstrated, MARS1 immunofluorescence staining shows similar results as conventional Pap staining. [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] In addition, LBC has been shown to have better diagnostic performance than conventional smear and biopsy methods. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] Despite these limitations, the present study demonstrates that the CFM can help increase the sensitivity of diagnosing indeterminate biliary strictures.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eIn conclusion, the high sensitivity and similar accuracy of the CFM compared to the CCM indicates that the CFM could be used as an additional brush cytology method. Further prospective studies are needed to validate these findings.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAUTHOR CONTRIBUTIONS\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSIJ had full access to all study data and takes responsibility for the integrity of the data and the accuracy of the data analysis.\u003c/p\u003e\n\u003cp\u003eStudy concept and design: SIJ and JHC\u003c/p\u003e\n\u003cp\u003eAcquisition, analysis, or interpretation of data: MJS, JHN, SJ, THL, JHC, CIK, DUK, and SIJ\u003c/p\u003e\n\u003cp\u003eDrafting of the manuscript: MJS and SIJ\u003c/p\u003e\n\u003cp\u003eCritical revision of the manuscript for important intellectual content: MJS and SIJ\u003c/p\u003e\n\u003cp\u003eStatistical analysis: MJS\u003c/p\u003e\n\u003cp\u003eObtained funding: None\u003c/p\u003e\n\u003cp\u003eAdministrative, technical, or material support: JHN, SJ, THL, JHC, CIK, DUK, and SIJ\u003c/p\u003e\n\u003cp\u003eStudy supervision: SIJ and JHC\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCONFLICT OF INTEREST DISCLOSURE\u003c/strong\u003e: None reported.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eACKNOWLEDGEMENT\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFUNDING/SUPPORT\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by a clinical research grant from Koran Pancreatobiliary Association in 2023 (S.M.J), NRF-2018M3A9F7062524(S.I.J) from the National Research Foundation, MSIT of Korea, and Korea Gastrointestinal Endoscopy Research Foundation Pharmaceutical Research Fund (S.I.J).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cbr\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003ePereira SP, Goodchild G, Webster GJM. The endoscopist and malignant and non-malignant biliary obstruction. Biochim Biophys Acta Mol Basis Dis. 2018;1864:1478\u0026ndash;1483. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.bbadis.2017.09.013\u003c/span\u003e\u003cspan address=\"10.1016/j.bbadis.2017.09.013\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSun B, Moon JH, Cai Q, et al. Review article: Asia-Pacific consensus recommendations on endoscopic tissue acquisition for biliary strictures. Aliment Pharmacol Ther. 2018;48:138\u0026ndash;151. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/apt.14811\u003c/span\u003e\u003cspan address=\"10.1111/apt.14811\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePonchon T, Gagnon P, Berger F, et al. Value of endobiliary brush cytology and biopsies for the diagnosis of malignant bile duct stenosis: results of a prospective study. Gastrointestinal endoscopy. 1995;42:565\u0026ndash;572.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGlasbrenner B, Ardan M, Boeck W, et al. Prospective evaluation of brush cytology of biliary strictures during endoscopic retrograde cholangiopancreatography. Endoscopy. 1999;31:712\u0026ndash;717.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDe Bellis M, Sherman S, Fogel EL, et al. Tissue sampling at ERCP in suspected malignant biliary strictures (Part 1). Gastrointestinal endoscopy. 2002;56:552\u0026ndash;561.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJin YH, Kim SH, Park CK. Diagnostic criteria for malignancy in bile cytology and its usefulness. J Korean Med Sci. 1999;14:643\u0026ndash;647. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3346/jkms.1999.14.6.643\u003c/span\u003e\u003cspan address=\"10.3346/jkms.1999.14.6.643\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHarada H, Sasaki T, Yamamoto N, et al. Assessment of endoscopic aspiration cytology and endoscopic retrograde cholangio-pancreatography in patients with cancer of the hepato-biliary tract. Part II. Gastroenterol Jpn. 1977;12:59\u0026ndash;64. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/bf02774003\u003c/span\u003e\u003cspan address=\"10.1007/bf02774003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCobb CJ, Floyd WN, Jr. Usefulness of bile cytology in the diagnostic management of patients with biliary tract obstruction. Acta Cytol. 1985;29:93\u0026ndash;100.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLeung JW, Sung JY, Chung SC, et al. Endoscopic scraping biopsy of malignant biliary strictures. Gastrointest Endosc. 1989;35:65\u0026ndash;66. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/s0016-5107(89)72696-1\u003c/span\u003e\u003cspan address=\"10.1016/s0016-5107(89)72696-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFoutch PG, Harlan JR, Kerr D, et al. Wire-guided brush cytology: a new endoscopic method for diagnosis of bile duct cancer. Gastrointest Endosc. 1989;35:243\u0026ndash;247. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/s0016-5107(89)72767-x\u003c/span\u003e\u003cspan address=\"10.1016/s0016-5107(89)72767-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFoutch PG, Kerr DM, Harlan JR, et al. A prospective, controlled analysis of endoscopic cytotechniques for diagnosis of malignant biliary strictures. Am J Gastroenterol. 1991;86:577\u0026ndash;580.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChang L, French S, Hierro M, et al. A prospective study comparing endobiliary biopsy, brush and aspiration cytology during ERCP in diagnosing biliary obstructive lesions. Am J Gastroenterol. 1992;87:1282.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFarrell RJ, Jain AK, Brandwein SL, et al. The combination of stricture dilation, endoscopic needle aspiration, and biliary brushings significantly improves diagnostic yield from malignant bile duct strictures. Gastrointest Endosc. 2001;54:587\u0026ndash;594. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1067/mge.2001.118715\u003c/span\u003e\u003cspan address=\"10.1067/mge.2001.118715\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ede Bellis M, Fogel EL, Sherman S, et al. Influence of stricture dilation and repeat brushing on the cancer detection rate of brush cytology in the evaluation of malignant biliary obstruction. Gastrointest Endosc. 2003;58:176\u0026ndash;182. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1067/mge.2003.345\u003c/span\u003e\u003cspan address=\"10.1067/mge.2003.345\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFogel EL, deBellis M, McHenry L, et al. Effectiveness of a new long cytology brush in the evaluation of malignant biliary obstruction: a prospective study. Gastrointest Endosc. 2006;63:71\u0026ndash;77. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.gie.2005.08.039\u003c/span\u003e\u003cspan address=\"10.1016/j.gie.2005.08.039\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDumonceau JM, Macias Gomez C, Casco C, et al. Grasp or brush for biliary sampling at endoscopic retrograde cholangiography? A blinded randomized controlled trial. Am J Gastroenterol. 2008;103:333\u0026ndash;340. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1572-0241.2007.01543.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1572-0241.2007.01543.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSugimoto S, Matsubayashi H, Kimura H, et al. Diagnosis of bile duct cancer by bile cytology: usefulness of post-brushing biliary lavage fluid. Endosc Int Open. 2015;3:E323-328. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1055/s-0034-1391666\u003c/span\u003e\u003cspan address=\"10.1055/s-0034-1391666\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWakasa T, Inayama K, Honda T, et al. Brushing cytology of the biliary tract: bile juice from the ERCP sheath tube provides cell-rich smear samples. Acta Cytol. 2014;58:398\u0026ndash;405. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1159/000364852\u003c/span\u003e\u003cspan address=\"10.1159/000364852\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNur AM, Salim M, Boerner S, et al. High Diagnostic Yield of Endoscopic Retrograde Cholangiopancreatography Brush Cytology for Indeterminate Strictures. J Can Assoc Gastroenterol. 2022;5:234\u0026ndash;239. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/jcag/gwac011\u003c/span\u003e\u003cspan address=\"10.1093/jcag/gwac011\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAmog-Jones GF, Chandra S, Jensen C, et al. Including the Sheath Rinse to Improve Cellular Yield in Biliary Brushing Cytology. Clin Endosc. 2017;50:614\u0026ndash;616. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5946/ce.2017.113\u003c/span\u003e\u003cspan address=\"10.5946/ce.2017.113\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJang SI, Nahm JH, Kwon NH, et al. Clinical utility of methionyl-tRNA synthetase 1 immunostaining in cytologic brushings of indeterminate biliary strictures: a multicenter prospective study. Gastrointest Endosc. 2021;94:733\u0026ndash;741 e734. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.gie.2021.04.026\u003c/span\u003e\u003cspan address=\"10.1016/j.gie.2021.04.026\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJang SI, Kwon NH, Lim BJ, et al. New staining method using methionyl-tRNA synthetase 1 antibody for brushing cytology of bile duct cancer. Gastrointest Endosc. 2020;92:310\u0026ndash;319 e316. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.gie.2019.12.017\u003c/span\u003e\u003cspan address=\"10.1016/j.gie.2019.12.017\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePitman MB, Layfield LJ. Guidelines for pancreaticobiliary cytology from the Papanicolaou Society of Cytopathology: A review. Cancer Cytopathology. 2014;122:399\u0026ndash;411. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/cncy.21427\u003c/span\u003e\u003cspan address=\"10.1002/cncy.21427\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLuna LEM, Kipp B, Halling KC, et al. Advanced cytologic techniques for the detection of malignant pancreatobiliary strictures. Gastroenterology. 2006;131:1064\u0026ndash;1072.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKhashab MA, Fockens P, Al-Haddad MA. Utility of EUS in patients with indeterminate biliary strictures and suspected extrahepatic cholangiocarcinoma (with videos). Gastrointestinal endoscopy. 2012;76:1024\u0026ndash;1033.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBarr Fritcher EG, Voss JS, Jenkins SM, et al. Primary sclerosing cholangitis with equivocal cytology: fluorescence in situ hybridization and serum CA 19\u0026thinsp;\u0026ndash;\u0026thinsp;9 predict risk of malignancy. Cancer Cytopathol. 2013;121:708\u0026ndash;717. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/cncy.21331\u003c/span\u003e\u003cspan address=\"10.1002/cncy.21331\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSinghi AD, Nikiforova MN, Chennat J, et al. Integrating next-generation sequencing to endoscopic retrograde cholangiopancreatography (ERCP)-obtained biliary specimens improves the detection and management of patients with malignant bile duct strictures. Gut. 2020;69:52\u0026ndash;61. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1136/gutjnl-2018-317817\u003c/span\u003e\u003cspan address=\"10.1136/gutjnl-2018-317817\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePisapia P, Pepe F, Sgariglia R, et al. Next generation sequencing in cytology. Cytopathology. 2021;32:588\u0026ndash;595. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/cyt.12974\u003c/span\u003e\u003cspan address=\"10.1111/cyt.12974\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKamp E, Dinjens WNM, van Velthuysen MF, et al. Next-generation sequencing mutation analysis on biliary brush cytology for differentiation of benign and malignant strictures in primary sclerosing cholangitis. Gastrointest Endosc. 2023;97:456\u0026ndash;465.e456. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.gie.2022.10.014\u003c/span\u003e\u003cspan address=\"10.1016/j.gie.2022.10.014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim BW, Oh CM, Choi HY, et al. Incidence and Overall Survival of Biliary Tract Cancers in South Korea from 2006 to 2015: Using the National Health Information Database. Gut Liver. 2019;13:104\u0026ndash;113. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5009/gnl18105\u003c/span\u003e\u003cspan address=\"10.5009/gnl18105\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnderson MA, Fisher L, Jain R, et al. Complications of ERCP. Gastrointest Endosc. 2012;75:467\u0026ndash;473. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.gie.2011.07.010\u003c/span\u003e\u003cspan address=\"10.1016/j.gie.2011.07.010\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJenssen C, Alvarez-S\u0026aacute;nchez MV, Napol\u0026eacute;on B, et al. Diagnostic endoscopic ultrasonography: assessment of safety and prevention of complications. World J Gastroenterol. 2012;18:4659\u0026ndash;4676. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3748/wjg.v18.i34.4659\u003c/span\u003e\u003cspan address=\"10.3748/wjg.v18.i34.4659\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee MW, Paik WH, Lee SH, et al. Usefulness of Liquid-Based Cytology in Diagnosing Biliary Tract Cancer Compared to Conventional Smear and Forceps Biopsy. Dig Dis Sci. 2022. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10620-022-07535-3\u003c/span\u003e\u003cspan address=\"10.1007/s10620-022-07535-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLinder J. Recent advances in thin-layer cytology. Diagn Cytopathol. 1998;18:24\u0026ndash;32. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/(sici)1097-0339(199801)18:1\u0026lt;24::aid-dc5\u0026gt;3.0.co;2-u\u003c/span\u003e\u003cspan address=\"10.1002/(sici)1097-0339(199801)18:1%3C24::aid-dc5%3E3.0.co;2-u\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChun JW, Lee K, Lee SH, et al. Comparison of liquid-based cytology with conventional smear cytology for EUS-guided FNA of solid pancreatic masses: a prospective randomized noninferiority study. Gastrointest Endosc. 2020;91:837\u0026ndash;846 e831. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.gie.2019.11.018\u003c/span\u003e\u003cspan address=\"10.1016/j.gie.2019.11.018\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWright PK, Marshall J, Desai M. Comparison of SurePath\u0026reg; and ThinPrep\u0026reg; liquid-based cervical cytology using positive predictive value, atypical predictive value and total predictive value as performance indicators. Cytopathology. 2010;21:374\u0026ndash;378. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1365-2303.2010.00772.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1365-2303.2010.00772.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"catheter flushing method, brush cytology, ERCP, indeterminate biliary stricture","lastPublishedDoi":"10.21203/rs.3.rs-3911988/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3911988/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground and Aim: \u003c/strong\u003eEndobiliary brushing is usually performed in the diagnosis of indeterminate biliary strictures; however, in this setting, brush cytology is limited by a low diagnostic yield and sensitivity. Here, we evaluated whether the catheter flushing method (CFM) could improve cellularity and diagnostic performance compared with the conventional cytologic method (CCM).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eEndobiliary brushings were obtained during endoscopic retrograde cholangiopancreatography (ERCP) from patients with biliary strictures enrolled at six tertiary hospitals. Additional CFM was performed after brushing. Using liquid-based cytologic preparations of samples, we assessed the diagnostic performance of the CCM using Pap staining and the CFM using methionyl-transfer RNA synthetase 1 (MARS1) immunofluorescence staining.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e From a total of 399 patients (malignant, 253; benign, 146), 374 CCM samples and 361 CFM samples contained adequate cells, with no significant difference in diagnostic yield (93.7% vs. 90.5%, respectively, \u003cem\u003eP\u003c/em\u003e = 0.721). The sensitivity of the CFM (90.3%) was significantly higher than that of the CCM (75.1%; \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001), with no significant difference in accuracy between methods (81.2% vs. 82.6%, respectively; \u003cem\u003eP\u003c/em\u003e = 0.608).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions: \u003c/strong\u003eDiagnostic yield was equivalent between CCM and CFM. Also, the high sensitivity and similar accuracy of the CFM compared with the CCM indicates that the CFM could be an additional brush cytology method for detecting malignancy in patients with indeterminant biliary strictures. Further prospective studies are needed to validate these findings.\u003c/p\u003e","manuscriptTitle":"The catheter flushing method increases the diagnostic yield of brushing cytology for biliary strictures","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-07 19:37:09","doi":"10.21203/rs.3.rs-3911988/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"82f7b291-816c-47e5-af63-4c30af46aeeb","owner":[],"postedDate":"February 7th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-07-17T07:59:13+00:00","versionOfRecord":[],"versionCreatedAt":"2024-02-07 19:37:09","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3911988","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3911988","identity":"rs-3911988","version":["v1"]},"buildId":"_2-kVJe1T_tPrBINL-cwx","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}