Obscured appendiceal wall on unenhanced CT: A sensitive indicator for the diagnosis of complicated appendicitis

Obscured appendiceal wall on unenhanced CT: A sensitive indicator for the diagnosis of complicated appendicitis | 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 Obscured appendiceal wall on unenhanced CT: A sensitive indicator for the diagnosis of complicated appendicitis Lei Wu, Xiao-Yu Chen, Jian-Dong Lu, Zhi-Guo Zhang, Xu-Ping Mao This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6108865/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 Objectives To retrospectively evaluate the potential role of an obscured appendiceal wall on unenhanced CT in the preoperative prediction of complicated appendicitis. Methods This retrospective study was approved by our institutional review board, and informed consent was waived. A total of 57 patients with surgically and pathologically confirmed appendicitis were analyzed from January 1, 2021, to June 30, 2024. The obscured appendiceal wall was assessed alongside four other specific CT findings and clinical data. Univariate statistical analyses were performed to examine associations between CT signs and complicated appendicitis. Kappa statistics were calculated to assess interobserver agreement. Results The study included 32 men (56.1%) and 25 women (43.9%) with a median age of 60 years. Of the 57 patients, 34 had uncomplicated appendicitis and 23 had complicated appendicitis. The obscured appendiceal wall showed the highest sensitivity for predicting complicated appendicitis, with a sensitivity of 81% (95% CI, 57–94%) and a specificity of 85% (95% CI, 68–94%). Interobserver agreement was fair (κ = 0.557; 95% CI, 0.341–0.773). Conclusion An obscured appendiceal wall is a sensitive and valuable indicator for diagnosing complicated appendicitis. Its detection can help reduce false-negative rates, preventing delayed diagnosis and treatment. Acute appendicitis Obscured appendiceal wall Tomography X-ray computed Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Acute appendicitis is believed to result from luminal obstruction caused by various factors, leading to increased mucus secretion and bacterial overgrowth. This, in turn, causes wall strain, necrosis, and potential perforation[ 1 ]. It is one of the most common causes of acute abdominal pain, with a lifetime risk of 8.6% in males and 6.7% in females[ 2 ]. Appendicitis is a frequent abdominal emergency that typically requires surgical intervention[ 3 – 5 ]. Although appendectomy remains the standard treatment for acute appendicitis[ 6 ], there has been ongoing debate regarding its necessity. Conservative management may be adequate for uncomplicated cases[ 7 ]. In contrast, complicated appendicitis carries an increased risk of postoperative complications such as infection, intra-abdominal sepsis, and adhesive intestinal obstruction. This may complicate laparoscopic appendectomy, potentially requiring conversion to open surgery[ 8 , 9 ]. Therefore, preoperative noninvasive imaging to diagnose complicated appendicitis is crucial, as it could help guide more optimal treatment strategies. Computed tomography (CT) has proven to be a fast and accurate imaging modality for diagnosing appendicitis[ 4 ], and is widely regarded as the first-line imaging test for patients suspected of having acute appendicitis[ 4 , 6 , 10 – 12 ], due to its excellent diagnostic performance[ 13 – 15 ]. In clinical practice, distinguishing complicated from uncomplicated appendicitis is as critical as diagnosing appendicitis itself, particularly when considering conservative management. Several studies have shown that CT can accurately diagnose complicated appendicitis[ 4 , 6 , 12 , 16 , 17 ]. However, most prior research on CT scans involved the use of intravenous and/or oral contrast. While contrast-enhanced CT has been shown to aid in diagnosing appendicitis and differentiating it from other causes of acute abdominal pain[ 18 , 19 ], its clinical application may be limited in certain cases due to drawbacks such as excessive radiation exposure, allergy histories, poor renal function, or limited availability in emergency settings. In our clinical practice, we have observed that complicated appendicitis often presents with an obscured local appendiceal wall on non-contrast CT scans. However, this observation has not been thoroughly evaluated in previous studies. Therefore, the aim of our study was to retrospectively assess the potential role of this CT finding in the preoperative prediction of complicated appendicitis. Material and methods Patient selection Our institutional review board approved this study and waived the requirement for informed consent. Between January 1, 2021, and June 30, 2024, we retrospectively analyzed 372 consecutive patients with surgically and pathologically confirmed appendicitis who underwent CT at our hospital. Of these, 315 patients were excluded for the following reasons: (1) incomplete data (no contrast-enhanced CT images available) (n = 286); (2) CT performed more than 24 hours prior to appendectomy (n = 12); (3) prior antibiotic therapy before CT (n = 8); and (4) age under 14 years (n = 9). As a result, 57 patients were included in the final analysis. Figure 1 presents the patient flowchart. Reference standard The complicated appendicitis group included patients whose surgical reports indicated a perforated appendix, abscess formation, or purulent peritoneal fluid, or whose histopathological reports revealed perforated appendix, abscess formation, peritonitis, or gangrenous appendicitis. Imaging technique Imaging was performed using a 64-slice, 128-row spiral CT scanner (SIEMENS SOMATOM Definition AS). Prior to the examination, all patients underwent respiratory training to ensure they could hold their breath throughout the entire scanning process. After standard abdominal positioning, a non-contrast CT scan was conducted, covering the area from the diaphragm to the pelvic floor. The scan parameters were as follows: tube voltage of 120 kV, using Siemens Care Dose 4D intelligent mA with a reference value of 210 mAs, a single rotation scan time of 0.5 s, collimation of 128×0.6 mm, and a pitch of 1:0.6. The contrast-enhanced scan was performed using the Ulrich Medical CT Motion high-pressure injector (Model: YZB/GER 3978-2015). The contrast agent used was Iohexol injection (Yangtze River Pharmaceutical Group Co., Ltd.; iodine concentration: 30 g/100 mL), administered at an injection rate of 3 mL/s. Venous phase images were acquired 70–75 seconds post-injection. No oral contrast material was administered. For image reconstruction, the slice thickness and interval were both set to 2 mm, with a B20 convolution kernel. These images were transmitted to the PACS system. Images with a slice thickness of 1 mm, slice interval of 0.5 mm, and a B20 convolution kernel were transmitted to the Siemens syngo MMWP workstation (software version VE40A) for Multi-Planar Reformation (MPR) and Maximum Intensity Projection (MIP) reconstructions in the coronal and sagittal planes. The slice thickness and interval for these reconstructions were both set to 2 mm. Additionally, Curved Planar Reformation (CPR) and MIP reconstructions were performed along the appendiceal axis in each layer, with slice thicknesses of 1 mm, 2 mm, and 5 mm. All reconstructed images were transmitted to the PACS. Clinical and Imaging Evaluation One radiologist, who did not participate as a reader, abstracted the following data from each patient’s medical records: age, gender, time from symptom onset to diagnosis, laboratory results (including white blood cell count and C-reactive protein levels), surgical findings, and histological outcomes in cases of appendectomy. Two senior gastrointestinal radiologists, with 8 and 12 years of experience in emergency abdominal radiology, respectively, independently and retrospectively evaluated axial and multiplanar reconstruction images. They assessed the presence of an obscured appendiceal wall and the presence of four specific CT findings strongly associated with complicated appendicitis: focal enhancement defect, abscess, extraluminal air, and extraluminal appendicolith. The evaluation was performed on a workstation (PACS Carestream Health, Rochester, NY) with adjustable window settings. The reviewers were blinded to the surgical reports and final patient outcomes, though they were aware that their assessments were part of a research study focused on CT signs of acute appendicitis. Disagreements between the reviewers were resolved by consensus, with the assistance of a third radiologist who had 10 years of experience in abdominal radiology. The CT findings were defined as follows: (a) Obscured appendiceal wall was defined as the partial loss of definition and dissolution of the appendiceal wall, with decreased attenuation, making it poorly demarcated from the surrounding inflammatory exudate. (b) Focal enhancement defect was defined as the enhancement of specific segments of the appendiceal wall on imaging (indicating blood flow or inflammatory response) is attenuated or absent[20]. (c) An abscess was defined as a well-delineated focal fluid collection with a thick wall[6, 10, 11]. (d) Extraluminal air and appendicolith were characterized by the presence of free air outside the bowel lumen and the existence of an appendicolith outside the lumen, respectively[11]. Statistical analysis Statistical analyses were conducted using PASW Statistics version 27.0 (IBM Corp., Armonk, NY). Continuous variables were tested for normality using a Shapiro-Wilk test and were described as mean ± SD if normally distributed, and as median (interquartile range) otherwise. Categorical data were reported as frequencies and percentages. The Mann-Whitney U test was used for continuous variables that were not normally distributed, while Pearson’s chi-squared test or Fisher’s exact test was used for categorical variables. Diagnostic performance parameters (sensitivity, specificity, positive and negative predictive values) with their 95% confidence intervals (95% CIs) were calculated for each CT finding. Interobserver agreement regarding the CT signs was assessed by computing Cohen's κ coefficient. Values of κ were interpreted according to Landis and Koch[21]: κ = 0.21-0.40, poor agreement; κ = 0.41-0.60, fair agreement; κ = 0.61-0.80, good agreement; and κ > 0.80 excellent agreement. A two-sided P value of less than 0.05 was considered statistically significant. The results are reported in accordance with STARD guidelines[22]. Results Population Of the 57 included patients, 32 (56.1%) were men and 25 (43.9%) were women. The median age was 60 years (range, 24–87 years; interquartile range [IQR], 47.5–69.5 years). Table 1 summarizes their clinical, CT, and laboratory characteristics. The median time from symptom onset to diagnosis was 22 hours (range, 3–72 hours), which was significantly longer in the complicated appendicitis group (median, 32 hours; IQR, 24–48 hours) compared to the uncomplicated group (median, 15 hours; IQR, 10.5–22 hours) ( P < 0.001). Patients with complicated appendicitis had significantly higher CRP levels (87.2 mg/L vs. 17.1 mg/L, P < 0.001). In two patients with complicated appendicitis, the presence of an obscured appendiceal wall could not be identified on CT due to severe inflammatory exudation. Significant associations with complicated appendicitis were observed for the presence of an obscured appendiceal wall ( P < 0.001), focal enhancement defect ( P = 0.006), abscess ( P = 0.001), extraluminal air ( P = 0.007), and extraluminal appendicolith ( P = 0.003). Table 1 Comparison of clinical, CT and laboratory parameters in the groups with uncomplicated and complicated appendicitis, and interobserver agreement Variable All Uncomplicated appendicitis Complicated appendicitis P -value Kappa (95% CI) No. Of patients 57 (100%) 34 (59.6%) 23 (40.4%) — — Age (years) 57.72 ± 15.67 57.76 ± 14.14 57.65 ± 18.04 0.979 1 — Gender (Male/female) 32 (56.1%)/25 (43.9%) 20 (58.8%)/14 (41.2%) 12 (52.2%)/11 (47.8%) 0.620 2 — Time from symptom onset to diagnosis (hours) 22 (14, 32) 15 (10.5, 22) 32 (24, 48) < 0.001 3 — CRP level (mg/L) 41.21 (10.2, 86.7) 17.1 (4.26, 65.4) 87.2 (42.2, 206) < 0.001 3 — WBC count (1×10 9 /L) 9.7 (6.86, 11.97) 9.53 (6, 11.73) 9.83 (7.34, 13.48) 0.298 3 — Obscured appendiceal wall (Yes/no) a 22 (40%)/33 (60%) 5 (14.7%)/29 (85.3%) 17 (81%)/4 (19%) < 0.001 2 0.557 (0.341–0.773) Focal enhancement defect (Yes/no) 18 (31.6%)/39 (68.4%) 6 (17.6%)/28 (82.4%) 12 (52.2%)/11 (47.8%) 0.006 2 0.457 (0.222–0.692) Abscess (Yes / no) 8 (14%)/49 (86%) 0 (0%)/34 (100%) 8 (34.8%)/15 (65.2%) 0.001 4 0.378 (0.051–0.705) Extraluminal air (Yes / no) 6 (10.5%)/51 (89.5%) 0 (0%)/34 (100%) 6 (26.1%)/17 (73.9%) 0.007 4 0.675 (0.379–0.971) Extraluminal appendicolith (Yes / no) 7 (12.3%)/50 (87.7%) 0 (0%)/34 (100%) 7 (30.4%)/16 (69.6%) 0.003 4 0.710 (0.443–0.977) CRP, C-reactive protein. WBC, white blood cell. a Data were available for 55 patients, 34 with uncomplicated appendicitis and 21 with complicated appendicitis. 1. Independent t test; 2. Chi-squared test; 3. Mann-Whitney U test; 4. Correction for continuity of chi-squared test. Interobserver agreement The kappa coefficients for the obscured appendiceal wall and focal enhancement defect were 0.557 (95% CI, 0.341–0.773) and 0.457 (95% CI, 0.222–0.692), respectively, indicating fair agreement. Agreement for the extraluminal appendicolith was good (κ = 0.710; 95% CI, 0.443–0.977), as was the agreement for extraluminal air (κ = 0.675; 95% CI, 0.379–0.971). In contrast, the presence of an abscess showed poor interobserver agreement (κ = 0.378; 95% CI, 0.051–0.705). Reference standard Uncomplicated appendicitis was diagnosed in 34 of 57 patients (59.6%) (Fig. 2 ), while complicated appendicitis was found in 23 of 57 patients (40.4%) (Figs. 3 – 4 ). Of the patients with complicated appendicitis, 14 (60.9%) had perforation and 9 (39.1%) had gangrene (Table 2 ). Among those with complicated appendicitis, 8 patients (34.8%) were found to have an abscess upon histopathological examination. Table 2 Results of surgical examination and / or histopathological findings in the subgroup of patients with complicated appendicitis Case Surgical and / or Histopathological findings Location Abscess Obscured appendiceal wall 1 Perforation The apex of the appendix No Yes 2 Perforation The apex of the appendix No No 3 Perforation The base of the appendix No Yes 4 Perforation The body of the appendix No No 5 Gangrene The apex of the appendix No Yes 6 Gangrene The apex and body of the appendix No Yes 7 Perforation The apex and body of the appendix No Yes 8 Gangrene The body of the appendix No Yes 9 Gangrene The base of the appendix Yes / 10 Perforation The apex of the appendix No Yes 11 Perforation The body of the appendix No Yes 12 Perforation The body of the appendix No Yes 13 Gangrene The base of the appendix No / 14 Perforation The apex of the appendix Yes No 15 Perforation The apex and body of the appendix Yes Yes 16 Gangrene The apex of the appendix Yes Yes 17 Perforation The body of the appendix No Yes 18 Perforation The base of the appendix Yes Yes 19 Perforation The body of the appendix No No 20 Gangrene The body and base of the appendix Yes Yes 21 Gangrene The body of the appendix No Yes 22 Perforation The apex and body of the appendix Yes Yes 23 Gangrene The apex of the appendix Yes Yes CT findings The CT finding with the highest sensitivity for significantly predicting complicated appendicitis was an obscured appendiceal wall, which was observed in 22 patients (17 with complicated appendicitis and 5 with uncomplicated appendicitis). This sign demonstrated a sensitivity of 81% (95% CI, 57–94%) and specificity of 85% (95% CI, 68–94%). The positive predictive value (PPV) was 77% (95% CI, 54–91%), and the negative predictive value (NPV) was 88% (95% CI, 71–96%). Other findings, including focal enhancement defects, abscess, extraluminal air, and extraluminal appendicoliths, exhibited high specificity (ranging from 82–100%) but low sensitivity (ranging from 26–52%) for complicated appendicitis. Table 3 summarizes the diagnostic performance of each CT finding. Table 3 Diagnostic performance of CT findings for predicting complicated appendicitis Sensitivity Specificity PPV NPV Obscured appendiceal wall a 17/21 (81) [57–94] 29/34 (85) [68–94] 17/22 (77) [54–91] 29/33 (88) [71–96] Focal enhancement defect 12/23 (52) [31–73] 28/34 (82) [65–93] 12/18 (67) [41–86] 28/39 (72) [55–84] Abscess 8/23 (35) [17–57] 34/34 (100) [87–100] 8/8 (100) [60–100] 34/49 (69) [54–81] Extraluminal air 6/23 (26) [11–49] 34/34 (100) [87–100] 6/6 (100) [52–100] 34/51 (67) [52–79] Extraluminal appendicolith 7/23 (30) [14–53] 34/34 (100) [87–100] 7/7 (100) [56–100] 34/50 (68) [53–80] Data are numerator/denominator, data in parentheses are percentages, and data in brackets are 95% confidence intervals PPV positive predictive value, NPV negative predictive value a Data were available for 55 patients, 34 with uncomplicated appendicitis and 21 with complicated appendicitis. Discussion This study compared the differences in the obscured appendiceal wall and four other specific CT findings between patients with complicated and uncomplicated appendicitis. Our results demonstrated that an obscured appendiceal wall is a highly sensitive indicator for diagnosing complicated appendicitis, with a sensitivity of 81% and a specificity of 85%. Numerous studies have underscored the utility of CT imaging features in differentiating between complicated and uncomplicated appendicitis. Tsukada et al[ 23 ] reported that CT is an effective tool for preoperatively identifying patients with complicated appendicitis. Foley et al[ 24 ] found that a focal enhancement defect was significantly associated with perforation, with a sensitivity of 58.8% and a specificity of 85.7%. Horrow et al[ 6 ] concluded that the sensitivities of abscess, extraluminal air, and extraluminal appendicolith in diagnosing complicated appendicitis were 36%, 36%, and 20.5%, respectively, while all three features exhibited 100% specificity. Similarly, Tsuboi et al[ 25 ] reported sensitivities for abscess, extraluminal air, and extraluminal appendicolith of 37.5%, 22.5%, and 32.5%, respectively. However, as indicated in prior studies, most CT features associated with complicated appendicitis exhibit high specificity but low sensitivity. Moreover, certain findings, such as abscess, extraluminal air, and extraluminal appendicoliths, are not frequently observed in complicated appendicitis[ 6 , 26 ]. In contrast, the obscured appendiceal wall demonstrated high sensitivity (81%) for diagnosing complicated appendicitis, while maintaining satisfactory specificity (85%). A possible explanation for this finding is that obstruction of the appendiceal lumen increases intraluminal and intramural pressure, which in turn leads to thrombosis of small vessels in the appendiceal wall and stasis of lymphatic flow. This sequence of events causes progressive impairment of the appendiceal wall, resulting in distention and infiltration by inflammatory cells, particularly leukocytes. As pressure continues to rise, the necrotic appendiceal wall—especially the intramural muscle fibers—ruptures, releasing bacteria and pus[ 27 ]. On unenhanced CT images, localized necrosis causes obscuration and dissolution of parts of the appendiceal wall, resulting in low attenuation areas that are poorly demarcated from the surrounding inflammatory exudates. Nevertheless, four patients with complicated appendicitis did not exhibit an obscured appendiceal wall. Two potential explanations for this discrepancy are: (a) the presence of an unknown pathophysiological mechanism responsible for the absence of this finding, or (b) the necrosis of the appendiceal musculature is in its early stages, without significant inflammatory exudation. Furthermore, technical factors and imaging artifacts, such as volume averaging, may contribute to misinterpretation, particularly when the appendix is parallel or oblique to the scanning plane. Based on our experience, when the appendiceal wall is clearly visible despite surrounding inflammatory exudation, this finding is insufficient to diagnose an obscured appendiceal wall (Fig. 2 a). In such instances, this sign is more indicative of uncomplicated appendicitis rather than complicated appendicitis. In our study, other specific CT findings—including focal enhancement defects, abscess, extraluminal air, and extraluminal appendicoliths—showed high specificity (ranging from 82–100%) but low sensitivity (ranging from 26–52%) for complicated appendicitis, consistent with the findings of previous studies[ 6 , 24 , 25 ]. Several limitations of our study must be acknowledged. First, our cohort included only patients with surgically treated appendicitis, which may have introduced selection bias toward more severe cases. Second, the imaging protocol (both unenhanced and enhanced CT scans) was not routinely applied to all patients presenting with acute abdominal pain in the emergency department, potentially limiting the statistical power of our comparative analyses due to the small sample size. While our finding regarding obscured appendiceal walls is promising, it remains premature and requires further validation in a large, independent external cohort. Finally, we excluded patients who underwent appendectomy more than 24 hours after CT imaging to ensure that the CT findings were directly relevant to surgical and/or pathological outcomes. In summary, an obscured appendiceal wall is a sensitive and valuable indicator for diagnosing complicated appendicitis. Its identification may reduce the false-negative rate and help prevent delayed diagnosis and treatment. Abbreviations CT computed tomography CIs confidence intervals MPR Multi-Planar Reformation MIP Maximum Intensity Projection CPR Curved Planar Reformation IQR interquartile range CRP C-reactive protein WBC white blood cell PPV positive predictive value NPV negative predictive value Declarations Ethics approval and consent to participate The study was approved from the Independent Ethics Committee of Zhangjiagang TCM Hospital (2023/10-08) Author contributions Lei Wu and Xiao-Yu Chen contributed equally to this work. Lei Wu and Xiao-Yu Chen wrote the main manuscript text and Jian-Dong Lu prepared figures 1-4. Zhi-Guo Zhang and Xu-Ping Mao revised and edited the main manuscript text. All authors reviewed the manuscript. Funding: Supported by Suzhou Science and Technology for Youths for Promoting Health through Science and Education Project, No. KJXW2023064. Supported by National Mentorship Program for Health Youth Backbone Talent in Suzhou, No. Qngg2024035. Supported by Jiangsu Medical Vocational College Campus Collaborative Innovation Research Project, No. 20239604. Supported by Jiangsu Medical Vocational College Campus Collaborative Innovation Research Project, No. 202490616. Competing interests The authors declare that they have no competing interests. References Mandeville K, Monuteaux M, Pottker T, Bulloch B. Effects of Timing to Diagnosis and Appendectomy in Pediatric Appendicitis. Pediatr Emerg Care. 2015;31(11):753–8. Jaschinski T, Mosch C, Eikermann M, Neugebauer EAM. 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Tsukada K, Miyazaki T, Katoh H, Masuda N, Ojima H, Fukuchi M, Manda R, Fukai Y, Nakajima M, Ishizaki M, Motegi M, Ohsawa H, Mogi A, Okamura A, Tsunoda Y, Sohda M, Ohno T, Moteki T, Sekine T, Kuwano H. CT is useful for identifying patients with complicated appendicitis. Dig Liver Disease. 2004;36(3):195–8. Foley TA, Earnest F, Nathan MA, Hough DM, Schiller HJ, Hoskin TL. Differentiation of Nonperforated from Perforated Appendicitis: Accuracy of CT Diagnosis and Relationship of CT Findings to Length of Hospital Stay. Radiology. 2005;235(1):89–96. Tsuboi M, Takase K, Kaneda I, Ishibashi T, Yamada T, Kitami M, Higano S, Takahashi S. Perforated and Nonperforated Appendicitis: Defect in Enhancing Appendiceal Wall—Depiction with Multi–Detector Row CT. Radiology. 2008;246(1):142–7. Mehmet A. Is acute appendicitis complicated or uncomplicated? Approaching the question via computed tomography. %J Acta Radiol (Stockholm Sweden: 1987). 2023;64(5):1755–64. Moris D, Paulson EK, Pappas TN. Diagnosis and Management of Acute Appendicitis in Adults: A Review. JAMA. 2021;326(22):2299–311. 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-6108865","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":422189227,"identity":"f566ccff-f9b8-4163-bd35-477191e68e51","order_by":0,"name":"Lei Wu","email":"","orcid":"","institution":"Zhangjiagang TCM Hospital Affiliated to Nanjing University of Chinese Medicine","correspondingAuthor":false,"prefix":"","firstName":"Lei","middleName":"","lastName":"Wu","suffix":""},{"id":422189228,"identity":"a167f64c-9f27-4f02-a169-ef2d32d0ea2d","order_by":1,"name":"Xiao-Yu Chen","email":"","orcid":"","institution":"Zhangjiagang TCM Hospital Affiliated to Nanjing University of Chinese Medicine","correspondingAuthor":false,"prefix":"","firstName":"Xiao-Yu","middleName":"","lastName":"Chen","suffix":""},{"id":422189229,"identity":"89a6dd9a-db47-4895-91ad-9166a4278b50","order_by":2,"name":"Jian-Dong Lu","email":"","orcid":"","institution":"Zhangjiagang TCM Hospital Affiliated to Nanjing University of Chinese Medicine","correspondingAuthor":false,"prefix":"","firstName":"Jian-Dong","middleName":"","lastName":"Lu","suffix":""},{"id":422189230,"identity":"5945fee1-53e2-4773-952a-7dfa572a995c","order_by":3,"name":"Zhi-Guo Zhang","email":"","orcid":"","institution":"Zhangjiagang TCM Hospital Affiliated to Nanjing University of Chinese Medicine","correspondingAuthor":false,"prefix":"","firstName":"Zhi-Guo","middleName":"","lastName":"Zhang","suffix":""},{"id":422189232,"identity":"402f3fbb-40c1-40c6-a25f-0d594bcf28ab","order_by":4,"name":"Xu-Ping Mao","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7ElEQVRIiWNgGAWjYPACCRjDhoefv4E0LWkykjMOkGbdYRuDhgT8SnTbDx+T5t1hkScf3fzswcc953kMGA4wfviYg1uL2Zm0ZGPeMxLFhneOmRvOeHabx5y5gVly5jY8Wg7kGD7mbZNI3DgjwUya58BtHsuGA2zMvPi0nH9jcBiiJf2b9J8D53gMDiQQ0HIDast8iRwzaYYDB4jR8izZcO4ZicQNMmfKDXsOJPNIzjjYjN8v55OPSbzdUZc4f3b7tgc/DtjZ8/M3H/zwEY8WMGBsYGAwuMHAhsQlBEBq5GfAtYyCUTAKRsEoQAUArTRWeIvZHnoAAAAASUVORK5CYII=","orcid":"","institution":"Zhangjiagang TCM Hospital Affiliated to Nanjing University of Chinese Medicine","correspondingAuthor":true,"prefix":"","firstName":"Xu-Ping","middleName":"","lastName":"Mao","suffix":""}],"badges":[],"createdAt":"2025-02-26 01:53:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6108865/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6108865/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":77683776,"identity":"b306baf4-1ec3-44c3-9ec2-2e686c24c780","added_by":"auto","created_at":"2025-03-04 08:54:08","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":192998,"visible":true,"origin":"","legend":"\u003cp\u003ePatient flowchart\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6108865/v1/8364d65cf596fd878be613e1.png"},{"id":77683755,"identity":"43464f11-5382-4820-879b-a971b14b8b9c","added_by":"auto","created_at":"2025-03-04 08:54:07","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1268768,"visible":true,"origin":"","legend":"\u003cp\u003eA 43-year-old man with uncomplicated appendicitis. \u003cstrong\u003ea\u003c/strong\u003e. A transverse, unenhanced CT image shows the appendiceal wall to be relatively intact, with slightly increased attenuation (arrowhead). Mild inflammatory changes are also noted in the adjacent fat tissue (arrow). \u003cstrong\u003eb\u003c/strong\u003e. A coronal reformation shows the entire length of the appendix within the coronal plane. The appendiceal wall remains relatively intact, with slightly increased attenuation (arrowheads). \u003cstrong\u003ec\u003c/strong\u003e. A photomicrograph demonstrates leukocyte infiltration of the appendiceal wall, though muscle fiber bundles are still present (arrowheads). Hematoxylin and eosin stain; original magnification ×20.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6108865/v1/0013c5690381b6daf80ea684.png"},{"id":77683747,"identity":"73938381-edc6-4969-bc4c-463dd055c6a8","added_by":"auto","created_at":"2025-03-04 08:54:05","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1149137,"visible":true,"origin":"","legend":"\u003cp\u003eA 56-year-old woman with complicated appendicitis (gangrene). \u003cstrong\u003ea. \u003c/strong\u003eA transverse unenhanced CT image shows partial obscuration and dissolution of the appendiceal wall with decreased attenuation at the apex of the appendix. This area is poorly demarcated from the surrounding inflammatory exudate (arrowhead). \u003cstrong\u003eb. \u003c/strong\u003eA coronal reformation demonstrates the entire length of the appendix within the coronal plane. However, the appendiceal wall is partially obscured with low attenuation (arrowhead). \u003cstrong\u003ec. \u003c/strong\u003ePathological examination reveals progressive impairment of the appendiceal wall with infiltration of massive leukocytes. The muscle fiber bundles are severely damaged, with muscle fibers appearing broken and loose (asterisks), contributing to the decreased attenuation. Hematoxylin and eosin stain; original magnification ×20.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6108865/v1/e9ca3b0feaf1eb53e1aa6238.png"},{"id":77683763,"identity":"7f078f28-9151-489d-b9d3-8a50705b834d","added_by":"auto","created_at":"2025-03-04 08:54:07","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":3517229,"visible":true,"origin":"","legend":"\u003cp\u003eA 58-year-old man with complicated appendicitis (perforation). \u003cstrong\u003ea. \u003c/strong\u003eThe appendiceal wall is obscured at the apex of the appendix on the coronal reconstructed plane (arrowhead). \u003cstrong\u003eb. \u003c/strong\u003eNo focal enhancement defect is observed on the contrast-enhanced CT scan.\u003cstrong\u003e c. \u003c/strong\u003eA photomicrograph shows a disruption in the continuity of the appendiceal muscular layer (arrowheads), indicating perforation. Hematoxylin and eosin stain; original magnification ×20.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6108865/v1/317e87408a4d9ff2bf8dfec0.png"},{"id":77711700,"identity":"6acbcea8-0348-4404-8cbc-945bcff96fb8","added_by":"auto","created_at":"2025-03-04 13:08:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8838062,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6108865/v1/9f4bee44-7a28-4df4-a391-42d45d91223f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Obscured appendiceal wall on unenhanced CT: A sensitive indicator for the diagnosis of complicated appendicitis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAcute appendicitis is believed to result from luminal obstruction caused by various factors, leading to increased mucus secretion and bacterial overgrowth. This, in turn, causes wall strain, necrosis, and potential perforation[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. It is one of the most common causes of acute abdominal pain, with a lifetime risk of 8.6% in males and 6.7% in females[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Appendicitis is a frequent abdominal emergency that typically requires surgical intervention[\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Although appendectomy remains the standard treatment for acute appendicitis[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], there has been ongoing debate regarding its necessity. Conservative management may be adequate for uncomplicated cases[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. In contrast, complicated appendicitis carries an increased risk of postoperative complications such as infection, intra-abdominal sepsis, and adhesive intestinal obstruction. This may complicate laparoscopic appendectomy, potentially requiring conversion to open surgery[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Therefore, preoperative noninvasive imaging to diagnose complicated appendicitis is crucial, as it could help guide more optimal treatment strategies.\u003c/p\u003e \u003cp\u003eComputed tomography (CT) has proven to be a fast and accurate imaging modality for diagnosing appendicitis[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], and is widely regarded as the first-line imaging test for patients suspected of having acute appendicitis[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], due to its excellent diagnostic performance[\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. In clinical practice, distinguishing complicated from uncomplicated appendicitis is as critical as diagnosing appendicitis itself, particularly when considering conservative management. Several studies have shown that CT can accurately diagnose complicated appendicitis[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. However, most prior research on CT scans involved the use of intravenous and/or oral contrast. While contrast-enhanced CT has been shown to aid in diagnosing appendicitis and differentiating it from other causes of acute abdominal pain[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], its clinical application may be limited in certain cases due to drawbacks such as excessive radiation exposure, allergy histories, poor renal function, or limited availability in emergency settings.\u003c/p\u003e \u003cp\u003eIn our clinical practice, we have observed that complicated appendicitis often presents with an obscured local appendiceal wall on non-contrast CT scans. However, this observation has not been thoroughly evaluated in previous studies. Therefore, the aim of our study was to retrospectively assess the potential role of this CT finding in the preoperative prediction of complicated appendicitis.\u003c/p\u003e"},{"header":"Material and methods","content":"\u003cp\u003e\u003cstrong\u003ePatient selection\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOur institutional review board approved this study and waived the requirement for informed consent. Between January 1, 2021, and June 30, 2024, we retrospectively analyzed 372 consecutive patients with surgically and pathologically confirmed appendicitis who underwent CT at our hospital. Of these, 315 patients were excluded for the following reasons: (1) incomplete data (no contrast-enhanced CT images available) (n = 286); (2) CT performed more than 24 hours prior to appendectomy (n = 12); (3) prior antibiotic therapy before CT (n = 8); and (4) age under 14 years (n = 9). As a result, 57 patients were included in the final analysis. Figure 1 presents the patient flowchart.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eReference standard\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe complicated appendicitis group included patients whose surgical reports indicated a perforated appendix, abscess formation, or purulent peritoneal fluid, or whose histopathological reports revealed perforated appendix, abscess formation, peritonitis, or gangrenous appendicitis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eImaging technique\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eImaging was performed using a 64-slice, 128-row spiral CT scanner (SIEMENS SOMATOM Definition AS). Prior to the examination, all patients underwent respiratory training to ensure they could hold their breath throughout the entire scanning process. After standard abdominal positioning, a non-contrast CT scan was conducted, covering the area from the diaphragm to the pelvic floor. The scan parameters were as follows: tube voltage of 120 kV, using Siemens Care Dose 4D intelligent mA with a reference value of 210 mAs, a single rotation scan time of 0.5 s, collimation of 128\u0026times;0.6 mm, and a pitch of 1:0.6. The contrast-enhanced scan was performed using the Ulrich Medical CT Motion high-pressure injector (Model: YZB/GER 3978-2015). The contrast agent used was Iohexol injection (Yangtze River Pharmaceutical Group Co., Ltd.; iodine concentration: 30 g/100 mL), administered at an injection rate of 3 mL/s. Venous phase images were acquired 70\u0026ndash;75 seconds post-injection. No oral contrast material was administered.\u003c/p\u003e\n\u003cp\u003eFor image reconstruction, the slice thickness and interval were both set to 2 mm, with a B20 convolution kernel. These images were transmitted to the PACS system. Images with a slice thickness of 1 mm, slice interval of 0.5 mm, and a B20 convolution kernel were transmitted to the Siemens syngo MMWP workstation (software version VE40A) for Multi-Planar Reformation (MPR) and Maximum Intensity Projection (MIP) reconstructions in the coronal and sagittal planes. The slice thickness and interval for these reconstructions were both set to 2 mm. Additionally, Curved Planar Reformation (CPR) and MIP reconstructions were performed along the appendiceal axis in each layer, with slice thicknesses of 1 mm, 2 mm, and 5 mm. All reconstructed images were transmitted to the PACS.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical and Imaging Evaluation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOne radiologist, who did not participate as a reader, abstracted the following data from each patient\u0026rsquo;s medical records: age, gender, time from symptom onset to diagnosis, laboratory results (including white blood cell count and C-reactive protein levels), surgical findings, and histological outcomes in cases of appendectomy.\u003c/p\u003e\n\u003cp\u003eTwo senior gastrointestinal radiologists, with 8 and 12 years of experience in emergency abdominal radiology, respectively, independently and retrospectively evaluated axial and multiplanar reconstruction images. They assessed the presence of an obscured appendiceal wall and the presence of four specific CT findings strongly associated with complicated appendicitis: focal enhancement defect, abscess, extraluminal air, and extraluminal appendicolith. The evaluation was performed on a workstation (PACS Carestream Health, Rochester, NY) with adjustable window settings. The reviewers were blinded to the surgical reports and final patient outcomes, though they were aware that their assessments were part of a research study focused on CT signs of acute appendicitis. Disagreements between the reviewers were resolved by consensus, with the assistance of a third radiologist who had 10 years of experience in abdominal radiology.\u003c/p\u003e\n\u003cp\u003eThe CT findings were defined as follows:\u003c/p\u003e\n\u003cp\u003e(a) Obscured appendiceal wall was defined as the partial loss of definition and dissolution of the appendiceal wall, with decreased attenuation, making it poorly demarcated from the surrounding inflammatory exudate.\u003c/p\u003e\n\u003cp\u003e(b) Focal enhancement defect was defined as the enhancement of specific segments of the appendiceal wall on imaging (indicating blood flow or inflammatory response) is attenuated or absent[20].\u003c/p\u003e\n\u003cp\u003e(c) An abscess was defined as a well-delineated focal fluid collection with a thick wall[6, 10, 11].\u003c/p\u003e\n\u003cp\u003e(d) Extraluminal air and appendicolith were characterized by the presence of free air outside the bowel lumen and the existence of an appendicolith outside the lumen, respectively[11].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStatistical analyses were conducted using PASW Statistics version 27.0 (IBM Corp., Armonk, NY). Continuous variables were tested for normality using a Shapiro-Wilk test and were described as mean \u0026plusmn; SD if normally distributed, and as median (interquartile range) otherwise. Categorical data were reported as frequencies and percentages. The Mann-Whitney U test was used for continuous variables that were not normally distributed, while Pearson\u0026rsquo;s chi-squared test or Fisher\u0026rsquo;s exact test was used for categorical variables. Diagnostic performance parameters (sensitivity, specificity, positive and negative predictive values) with their 95% confidence intervals (95% CIs) were calculated for each CT finding.\u003c/p\u003e\n\u003cp\u003eInterobserver agreement regarding the CT signs was assessed by computing Cohen\u0026apos;s \u0026kappa; coefficient. Values of \u0026kappa; were interpreted according to Landis and Koch[21]: \u0026kappa; = 0.21-0.40, poor agreement; \u0026kappa; = 0.41-0.60, fair agreement; \u0026kappa; = 0.61-0.80, good agreement; and \u0026kappa; \u0026gt; 0.80 excellent agreement. A two-sided P value of less than 0.05 was considered statistically significant. The results are reported in accordance with STARD guidelines[22].\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003ePopulation\u003c/h2\u003e \u003cp\u003eOf the 57 included patients, 32 (56.1%) were men and 25 (43.9%) were women. The median age was 60 years (range, 24\u0026ndash;87 years; interquartile range [IQR], 47.5\u0026ndash;69.5 years). Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e summarizes their clinical, CT, and laboratory characteristics. The median time from symptom onset to diagnosis was 22 hours (range, 3\u0026ndash;72 hours), which was significantly longer in the complicated appendicitis group (median, 32 hours; IQR, 24\u0026ndash;48 hours) compared to the uncomplicated group (median, 15 hours; IQR, 10.5\u0026ndash;22 hours) (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Patients with complicated appendicitis had significantly higher CRP levels (87.2 mg/L vs. 17.1 mg/L, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). In two patients with complicated appendicitis, the presence of an obscured appendiceal wall could not be identified on CT due to severe inflammatory exudation. Significant associations with complicated appendicitis were observed for the presence of an obscured appendiceal wall (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), focal enhancement defect (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.006), abscess (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001), extraluminal air (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.007), and extraluminal appendicolith (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003).\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\u003eComparison of clinical, CT and laboratory parameters in the groups with uncomplicated and complicated appendicitis, and interobserver agreement\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 \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAll\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eUncomplicated appendicitis\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eComplicated appendicitis\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eKappa (95% CI)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo. Of patients\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34 (59.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e23 (40.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57.72\u0026thinsp;\u0026plusmn;\u0026thinsp;15.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e57.76\u0026thinsp;\u0026plusmn;\u0026thinsp;14.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e57.65\u0026thinsp;\u0026plusmn;\u0026thinsp;18.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.979\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender (Male/female)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e32 (56.1%)/25 (43.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20 (58.8%)/14 (41.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12 (52.2%)/11 (47.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.620\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTime from symptom onset to diagnosis (hours)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22 (14, 32)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15 (10.5, 22)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e32 (24, 48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCRP level (mg/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41.21 (10.2, 86.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e17.1 (4.26, 65.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e87.2 (42.2, 206)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWBC count (1\u0026times;10\u003csup\u003e9\u003c/sup\u003e/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9.7 (6.86, 11.97)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.53 (6, 11.73)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.83 (7.34, 13.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.298\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eObscured appendiceal wall (Yes/no) \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22 (40%)/33 (60%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (14.7%)/29 (85.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17 (81%)/4 (19%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.557 (0.341\u0026ndash;0.773)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFocal enhancement defect (Yes/no)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18 (31.6%)/39 (68.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (17.6%)/28 (82.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12 (52.2%)/11 (47.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.006\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.457 (0.222\u0026ndash;0.692)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbscess (Yes / no)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8 (14%)/49 (86%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0%)/34 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8 (34.8%)/15 (65.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.001\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.378 (0.051\u0026ndash;0.705)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExtraluminal air (Yes / no)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6 (10.5%)/51 (89.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0%)/34 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6 (26.1%)/17 (73.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.007\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.675 (0.379\u0026ndash;0.971)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExtraluminal appendicolith (Yes / no)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (12.3%)/50 (87.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0%)/34 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (30.4%)/16 (69.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.003\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.710 (0.443\u0026ndash;0.977)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eCRP, C-reactive protein. WBC, white blood cell.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003csup\u003ea\u003c/sup\u003e Data were available for 55 patients, 34 with uncomplicated appendicitis and 21 with complicated appendicitis.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e1. Independent t test; 2. Chi-squared test; 3. Mann-Whitney U test; 4. Correction for continuity of chi-squared test.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eInterobserver agreement\u003c/h3\u003e\n\u003cp\u003e The kappa coefficients for the obscured appendiceal wall and focal enhancement defect were 0.557 (95% CI, 0.341\u0026ndash;0.773) and 0.457 (95% CI, 0.222\u0026ndash;0.692), respectively, indicating fair agreement. Agreement for the extraluminal appendicolith was good (κ\u0026thinsp;=\u0026thinsp;0.710; 95% CI, 0.443\u0026ndash;0.977), as was the agreement for extraluminal air (κ\u0026thinsp;=\u0026thinsp;0.675; 95% CI, 0.379\u0026ndash;0.971). In contrast, the presence of an abscess showed poor interobserver agreement (κ\u0026thinsp;=\u0026thinsp;0.378; 95% CI, 0.051\u0026ndash;0.705).\u003c/p\u003e \u003cp\u003e \u003cb\u003eReference standard\u003c/b\u003e \u003c/p\u003e \u003cp\u003eUncomplicated appendicitis was diagnosed in 34 of 57 patients (59.6%) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), while complicated appendicitis was found in 23 of 57 patients (40.4%) (Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Of the patients with complicated appendicitis, 14 (60.9%) had perforation and 9 (39.1%) had gangrene (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Among those with complicated appendicitis, 8 patients (34.8%) were found to have an abscess upon histopathological examination.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\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\u003eResults of surgical examination and / or histopathological findings in the subgroup of patients with complicated appendicitis\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCase\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSurgical and / or Histopathological findings\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLocation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAbscess\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eObscured appendiceal wall\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe apex of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe apex of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe base of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe body of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGangrene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe apex of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGangrene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe apex and body of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe apex and body of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGangrene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe body of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGangrene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe base of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe apex of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe body of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe body of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGangrene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe base of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe apex of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe apex and body of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGangrene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe apex of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe body of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe base of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe body of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGangrene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe body and base of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGangrene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe body of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe apex and body of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGangrene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThe apex of the appendix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eCT findings\u003c/h3\u003e\n\u003cp\u003eThe CT finding with the highest sensitivity for significantly predicting complicated appendicitis was an obscured appendiceal wall, which was observed in 22 patients (17 with complicated appendicitis and 5 with uncomplicated appendicitis). This sign demonstrated a sensitivity of 81% (95% CI, 57\u0026ndash;94%) and specificity of 85% (95% CI, 68\u0026ndash;94%). The positive predictive value (PPV) was 77% (95% CI, 54\u0026ndash;91%), and the negative predictive value (NPV) was 88% (95% CI, 71\u0026ndash;96%). Other findings, including focal enhancement defects, abscess, extraluminal air, and extraluminal appendicoliths, exhibited high specificity (ranging from 82\u0026ndash;100%) but low sensitivity (ranging from 26\u0026ndash;52%) for complicated appendicitis. Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e summarizes the diagnostic performance of each CT finding.\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\u003eDiagnostic performance of CT findings for predicting complicated appendicitis\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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 \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 \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eObscured appendiceal wall\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17/21 (81) [57\u0026ndash;94]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e29/34 (85) [68\u0026ndash;94]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17/22 (77) [54\u0026ndash;91]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e29/33 (88) [71\u0026ndash;96]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFocal enhancement defect\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12/23 (52) [31\u0026ndash;73]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28/34 (82) [65\u0026ndash;93]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12/18 (67) [41\u0026ndash;86]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e28/39 (72) [55\u0026ndash;84]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbscess\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8/23 (35) [17\u0026ndash;57]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34/34 (100) [87\u0026ndash;100]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8/8 (100) [60\u0026ndash;100]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e34/49 (69) [54\u0026ndash;81]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExtraluminal air\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6/23 (26) [11\u0026ndash;49]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34/34 (100) [87\u0026ndash;100]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6/6 (100) [52\u0026ndash;100]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e34/51 (67) [52\u0026ndash;79]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExtraluminal appendicolith\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7/23 (30) [14\u0026ndash;53]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34/34 (100) [87\u0026ndash;100]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7/7 (100) [56\u0026ndash;100]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e34/50 (68) [53\u0026ndash;80]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eData are numerator/denominator, data in parentheses are percentages, and data in brackets are 95% confidence intervals\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cem\u003ePPV\u003c/em\u003e positive predictive value, \u003cem\u003eNPV\u003c/em\u003e negative predictive value\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003csup\u003ea\u003c/sup\u003e Data were available for 55 patients, 34 with uncomplicated appendicitis and 21 with complicated appendicitis.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study compared the differences in the obscured appendiceal wall and four other specific CT findings between patients with complicated and uncomplicated appendicitis. Our results demonstrated that an obscured appendiceal wall is a highly sensitive indicator for diagnosing complicated appendicitis, with a sensitivity of 81% and a specificity of 85%.\u003c/p\u003e \u003cp\u003eNumerous studies have underscored the utility of CT imaging features in differentiating between complicated and uncomplicated appendicitis. Tsukada et al[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] reported that CT is an effective tool for preoperatively identifying patients with complicated appendicitis. Foley et al[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] found that a focal enhancement defect was significantly associated with perforation, with a sensitivity of 58.8% and a specificity of 85.7%. Horrow et al[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] concluded that the sensitivities of abscess, extraluminal air, and extraluminal appendicolith in diagnosing complicated appendicitis were 36%, 36%, and 20.5%, respectively, while all three features exhibited 100% specificity. Similarly, Tsuboi et al[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] reported sensitivities for abscess, extraluminal air, and extraluminal appendicolith of 37.5%, 22.5%, and 32.5%, respectively. However, as indicated in prior studies, most CT features associated with complicated appendicitis exhibit high specificity but low sensitivity. Moreover, certain findings, such as abscess, extraluminal air, and extraluminal appendicoliths, are not frequently observed in complicated appendicitis[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn contrast, the obscured appendiceal wall demonstrated high sensitivity (81%) for diagnosing complicated appendicitis, while maintaining satisfactory specificity (85%). A possible explanation for this finding is that obstruction of the appendiceal lumen increases intraluminal and intramural pressure, which in turn leads to thrombosis of small vessels in the appendiceal wall and stasis of lymphatic flow. This sequence of events causes progressive impairment of the appendiceal wall, resulting in distention and infiltration by inflammatory cells, particularly leukocytes. As pressure continues to rise, the necrotic appendiceal wall\u0026mdash;especially the intramural muscle fibers\u0026mdash;ruptures, releasing bacteria and pus[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. On unenhanced CT images, localized necrosis causes obscuration and dissolution of parts of the appendiceal wall, resulting in low attenuation areas that are poorly demarcated from the surrounding inflammatory exudates.\u003c/p\u003e \u003cp\u003eNevertheless, four patients with complicated appendicitis did not exhibit an obscured appendiceal wall. Two potential explanations for this discrepancy are: (a) the presence of an unknown pathophysiological mechanism responsible for the absence of this finding, or (b) the necrosis of the appendiceal musculature is in its early stages, without significant inflammatory exudation. Furthermore, technical factors and imaging artifacts, such as volume averaging, may contribute to misinterpretation, particularly when the appendix is parallel or oblique to the scanning plane. Based on our experience, when the appendiceal wall is clearly visible despite surrounding inflammatory exudation, this finding is insufficient to diagnose an obscured appendiceal wall (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). In such instances, this sign is more indicative of uncomplicated appendicitis rather than complicated appendicitis.\u003c/p\u003e \u003cp\u003eIn our study, other specific CT findings\u0026mdash;including focal enhancement defects, abscess, extraluminal air, and extraluminal appendicoliths\u0026mdash;showed high specificity (ranging from 82\u0026ndash;100%) but low sensitivity (ranging from 26\u0026ndash;52%) for complicated appendicitis, consistent with the findings of previous studies[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSeveral limitations of our study must be acknowledged. First, our cohort included only patients with surgically treated appendicitis, which may have introduced selection bias toward more severe cases. Second, the imaging protocol (both unenhanced and enhanced CT scans) was not routinely applied to all patients presenting with acute abdominal pain in the emergency department, potentially limiting the statistical power of our comparative analyses due to the small sample size. While our finding regarding obscured appendiceal walls is promising, it remains premature and requires further validation in a large, independent external cohort. Finally, we excluded patients who underwent appendectomy more than 24 hours after CT imaging to ensure that the CT findings were directly relevant to surgical and/or pathological outcomes.\u003c/p\u003e \u003cp\u003eIn summary, an obscured appendiceal wall is a sensitive and valuable indicator for diagnosing complicated appendicitis. Its identification may reduce the false-negative rate and help prevent delayed diagnosis and treatment.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ecomputed tomography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCIs\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003econfidence intervals\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMPR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMulti-Planar Reformation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMIP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMaximum Intensity Projection\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCPR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCurved Planar Reformation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIQR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003einterquartile range\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCRP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eC-reactive protein\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eWBC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ewhite blood cell\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePPV\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003epositive predictive value\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eNPV\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003enegative predictive value\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was approved from the Independent Ethics Committee of Zhangjiagang TCM Hospital (2023/10-08)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLei Wu and Xiao-Yu Chen contributed equally to this work.\u003c/p\u003e\n\u003cp\u003eLei Wu and Xiao-Yu Chen wrote the main manuscript text and Jian-Dong Lu prepared figures 1-4. Zhi-Guo Zhang and Xu-Ping Mao revised and edited the main manuscript text. All authors reviewed the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSupported by Suzhou Science and Technology for Youths for Promoting Health through Science and Education Project, No. KJXW2023064.\u003c/p\u003e\n\u003cp\u003eSupported by National Mentorship Program for Health Youth Backbone Talent in Suzhou, No. Qngg2024035.\u003c/p\u003e\n\u003cp\u003eSupported by Jiangsu Medical Vocational College Campus Collaborative Innovation Research Project, No. 20239604.\u003c/p\u003e\n\u003cp\u003eSupported by Jiangsu Medical Vocational College Campus Collaborative Innovation Research Project, No. 202490616.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMandeville K, Monuteaux M, Pottker T, Bulloch B. Effects of Timing to Diagnosis and Appendectomy in Pediatric Appendicitis. Pediatr Emerg Care. 2015;31(11):753\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJaschinski T, Mosch C, Eikermann M, Neugebauer EAM. Laparoscopic versus open appendectomy in patients with suspected appendicitis: a systematic review of meta-analyses of randomised controlled trials. BMC Gastroenterol 15(1) (2015).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrown JJ. Acute appendicitis: the radiologist's role. Radiology. 1991;180(1):13\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFoley TA, Earnest Ft, Nathan MA, Hough DM, Schiller HJ, Hoskin TL. Differentiation of nonperforated from perforated appendicitis: accuracy of CT diagnosis and relationship of CT findings to length of hospital stay. Radiology. 2005;235(1):89\u0026ndash;96.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLaghi A. Acute Appendicitis and Negative or Inconclusive Results at Initial US in Adult, Pediatric, and Pregnant Patients: What to Do Next? Radiology. 2018;288(3):728\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHorrow MM, White DS, Horrow JC. Differentiation of perforated from nonperforated appendicitis at CT. Radiology. 2003;227(1):46\u0026ndash;51.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoher D, Liberati A, Tetzlaff J, Altman DG, Group P. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med. 2009;6(7):e1000097.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu SI, Siewert B, Raptopoulos V, Hodin RA. Factors associated with conversion to laparotomy in patients undergoing laparoscopic appendectomy. J Am Coll Surg. 2002;194(3):298\u0026ndash;305.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSiewert B, Raptopoulos V, Liu SI, Hodin RA, Davis RB, Rosen MP. CT predictors of failed laparoscopic appendectomy. Radiology. 2003;229(2):415\u0026ndash;20.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBixby SD, Lucey BC, Soto JA, Theysohn JM, Ozonoff A, Varghese JC. Perforated versus nonperforated acute appendicitis: accuracy of multidetector CT detection. Radiology. 2006;241(3):780\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTsuboi M, Takase K, Kaneda I, Ishibashi T, Yamada T, Kitami M, Higano S, Takahashi S. Perforated and nonperforated appendicitis: defect in enhancing appendiceal wall\u0026ndash;depiction with multi-detector row CT. Radiology. 2008;246(1):142\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYeung KW, Chang MS, Hsiao CP. Evaluation of perforated and nonperforated appendicitis with CT. Clin Imaging. 2004;28(6):422\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDrake FT, Florence MG, Johnson MG, Jurkovich GJ, Kwon S, Schmidt Z, Thirlby RC, Flum DR, Collaborative S. Progress in the diagnosis of appendicitis: a report from Washington State's Surgical Care and Outcomes Assessment Program. Ann Surg. 2012;256(4):586\u0026ndash;94.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePickhardt PJ, Lawrence EM, Pooler BD, Bruce RJ. Diagnostic performance of multidetector computed tomography for suspected acute appendicitis. Ann Intern Med 154(12) (2011) 789\u0026thinsp;\u0026ndash;\u0026thinsp;96, W-291.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRaja AS, Wright C, Sodickson AD, Zane RD, Schiff GD, Hanson R, Baeyens PF, Khorasani R. Negative appendectomy rate in the era of CT: an 18-year perspective. Radiology. 2010;256(2):460\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin CJ, Chen JD, Tiu CM, Chou YH, Chiang JH, Lee CH, Chang CY, Yu C. Can ruptured appendicitis be detected preoperatively in the ED? Am J Emerg Med. 2005;23(1):60\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWu L, Zhang Z-G, Chen X-Y, Xu B-X, Mao X-P. Fascial involvement score on unenhanced CT potentially helps predict complicated appendicitis. Eur J Radiol 182 (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKamel IR, Goldberg SN, Keogan MT, Rosen MP, Raptopoulos V. Right lower quadrant pain and suspected appendicitis: nonfocused appendiceal CT\u0026ndash;review of 100 cases. Radiology. 2000;217(1):159\u0026ndash;63.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJacobs JE, Birnbaum BA, Macari M, Megibow AJ, Israel G, Maki DD, Aguiar AM, Langlotz CP. Acute appendicitis: comparison of helical CT diagnosis focused technique with oral contrast material versus nonfocused technique with oral and intravenous contrast material. Radiology. 2001;220(3):683\u0026ndash;90.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSuthikeeree W. Diagnostic Performance of CT Findings in Differentiation of Perforated from Nonperforated Appendicitis %J. J Med Association Thail =: Chotmaihet thangphaet. 2010;93(12):1422\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eL. J R, The measurement of observer agreement for categorical data. %J Biometrics, 33(1) (1977) 159\u0026ndash;74.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCohen JF, Korevaar DA, Altman DG, Bruns DE, Gatsonis CA, Hooft L, Irwig L, Levine D, Reitsma JB, de Vet HC, Bossuyt PM. STARD 2015 guidelines for reporting diagnostic accuracy studies: explanation and elaboration. BMJ Open. 2016;6(11):e012799.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTsukada K, Miyazaki T, Katoh H, Masuda N, Ojima H, Fukuchi M, Manda R, Fukai Y, Nakajima M, Ishizaki M, Motegi M, Ohsawa H, Mogi A, Okamura A, Tsunoda Y, Sohda M, Ohno T, Moteki T, Sekine T, Kuwano H. CT is useful for identifying patients with complicated appendicitis. Dig Liver Disease. 2004;36(3):195\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFoley TA, Earnest F, Nathan MA, Hough DM, Schiller HJ, Hoskin TL. Differentiation of Nonperforated from Perforated Appendicitis: Accuracy of CT Diagnosis and Relationship of CT Findings to Length of Hospital Stay. Radiology. 2005;235(1):89\u0026ndash;96.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTsuboi M, Takase K, Kaneda I, Ishibashi T, Yamada T, Kitami M, Higano S, Takahashi S. Perforated and Nonperforated Appendicitis: Defect in Enhancing Appendiceal Wall\u0026mdash;Depiction with Multi\u0026ndash;Detector Row CT. Radiology. 2008;246(1):142\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMehmet A. Is acute appendicitis complicated or uncomplicated? Approaching the question via computed tomography. %J Acta Radiol (Stockholm Sweden: 1987). 2023;64(5):1755\u0026ndash;64.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoris D, Paulson EK, Pappas TN. Diagnosis and Management of Acute Appendicitis in Adults: A Review. JAMA. 2021;326(22):2299\u0026ndash;311.\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":"Acute appendicitis, Obscured appendiceal wall, Tomography, X-ray computed","lastPublishedDoi":"10.21203/rs.3.rs-6108865/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6108865/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjectives\u003c/h2\u003e \u003cp\u003eTo retrospectively evaluate the potential role of an obscured appendiceal wall on unenhanced CT in the preoperative prediction of complicated appendicitis.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003e This retrospective study was approved by our institutional review board, and informed consent was waived. A total of 57 patients with surgically and pathologically confirmed appendicitis were analyzed from January 1, 2021, to June 30, 2024. The obscured appendiceal wall was assessed alongside four other specific CT findings and clinical data. Univariate statistical analyses were performed to examine associations between CT signs and complicated appendicitis. Kappa statistics were calculated to assess interobserver agreement.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe study included 32 men (56.1%) and 25 women (43.9%) with a median age of 60 years. Of the 57 patients, 34 had uncomplicated appendicitis and 23 had complicated appendicitis. The obscured appendiceal wall showed the highest sensitivity for predicting complicated appendicitis, with a sensitivity of 81% (95% CI, 57\u0026ndash;94%) and a specificity of 85% (95% CI, 68\u0026ndash;94%). Interobserver agreement was fair (κ\u0026thinsp;=\u0026thinsp;0.557; 95% CI, 0.341\u0026ndash;0.773).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eAn obscured appendiceal wall is a sensitive and valuable indicator for diagnosing complicated appendicitis. Its detection can help reduce false-negative rates, preventing delayed diagnosis and treatment.\u003c/p\u003e","manuscriptTitle":"Obscured appendiceal wall on unenhanced CT: A sensitive indicator for the diagnosis of complicated appendicitis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-04 08:53:37","doi":"10.21203/rs.3.rs-6108865/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":"27e10a23-e861-49ab-97c1-139af5ec4fd4","owner":[],"postedDate":"March 4th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-03-10T02:38:26+00:00","versionOfRecord":[],"versionCreatedAt":"2025-03-04 08:53:37","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6108865","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6108865","identity":"rs-6108865","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}