{"paper_id":"44f0a426-bc54-4f3f-90db-1560bc77944a","body_text":"Clin. Exp. Obstet. Gynecol. 2025; 52(12): 42077\nhttps://doi.org/10.31083/CEOG42077\nCopyright: © 2025 The Author(s). Published by IMR Press.\nThis is an open access article under the CC BY 4.0 license .\nPublisher’s Note: IMR Press stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.\nOriginal Research\nDiagnosis of Intestinal Endometriosis: A Multicenter Retrospective\nStudy\nNurhilal Kiziltoprak1,*\n , Farida Mustafayeva 2\n , Ayvaz Ulaş Urgancı3\n ,\nSerap Karaarslan4\n , Mehtap Toprak5\n , Hüsnü Ozan Şevik 6\n , Sezer Bulut 7\n ,\nFevzi Cengiz2\n , Erdinç Kamer 8\n , Ömer Faruk Özkan 1\n1Department of General Surgery, Istanbul Sultan Abdülhamid Han Research and Training Hospital, 34668 Istanbul, Türkiye\n2Department of General Surgery, Izmir Katip Çelebi University, 35620 Izmir, Türkiye\n3Department of General Surgery, Izmir Tınaztepe University, 35390 Izmir, Türkiye\n4Department of Pathology, Izmir Tınaztepe University, 35390 Izmir, Türkiye\n5Department of Pathology, Istanbul Sultan Abdülhamid Han Research and Training Hospital, 34668 Istanbul, Türkiye\n6Department of General Surgery, Başakşehir Çam and Sakura City Hospital, 34480 Istanbul, Türkiye\n7Department of General Surgery, Bakırköy Dr. Sadi Konuk Training and Research Hospital, 34147 Istanbul, Türkiye\n8Department of General Surgery, Izmir Faculty of Medicine, University of Health Sciences, 35170 Izmir, Türkiye\n*Correspondence: drnurhilalkiziltoprak@gmail.com (Nurhilal Kiziltoprak)\nAcademic Editor: Michael H. Dahan\nSubmitted: 22 May 2025 Revised: 17 October 2025 Accepted: 27 October 2025 Published: 25 December 2025\nAbstract\nBackground: Intestinal endometriosis occurs when endometrial-like tissue infiltrates the intestinal wall, most often affecting the sig-\nmoid colon and rectum. Methods: Between January 2012 and February 2025, patients with intestinal endometriosis who underwent\nsurgery were examined in five tertiary referral centers: Istanbul Sultan Abdülhamid Han Research and Training Hospital, Izmir Katip\nÇelebi University, Bakırköy Dr. Sadi Konuk Training and Research Hospital, Başakşehir Çam and Sakura City Hospital, and Izmir City\nHospital. Preoperative symptoms, demographic characteristics, menstrual status, operative times, intraoperative blood loss, surgical and\npathological findings, antibiotic use, and postoperative complications were retrospectively reviewed. Results: Emergency surgery was\nrequired in a significant number of patients (n = 35, 71.4%), primarily due to intestinal obstruction or acute abdomen presentations. Re-\nsection procedures included anterior or low anterior resections for rectosigmoid involvement and colectomies for colonic disease (n = 21,\n42.9%), appendectomies performed for acute appendicitis (n = 26, 53.1%), and small bowel resections for small intestinal diseases (n = 2,\n4.1%). Postoperative complications were observed in 8 patients, including ileus (n = 2), infections requiring antibiotics (n = 2, Grade II),\nintra-abdominal abscess requiring percutaneous drainage (n = 1, Grade IIIa), bleeding requiring reoperation (n = 1, Grade IIIb), incisional\nhernia (n = 1, Grade IIIa), and fat necrosis (n = 1, Grade I). Histopathological examination revealed transmural (full-thickness) bowel\nwall involvement in three patients and muscularis propria-limited involvement in two patients. One case involved a 67-year-old post-\nmenopausal woman who presented with bowel obstruction and required emergency surgery. Intraoperatively, a rectosigmoid stricture\nwithout a visible tumor was identified. Conclusion: Surgeons and clinicians should maintain a high index of suspicion for endometriosis\nin postmenopausal patients presenting with nonspecific gastrointestinal symptoms or when unexpected findings are encountered during\nabdominal surgery. Considering intestinal endometriosis in the differential diagnosis, even in the absence of typical risk factors such as\nhormone replacement therapy or a prior history of endometriosis, is essential for improving diagnostic accuracy and patient outcomes.\nKeywords: colon; differential diagnosis; intestinal endometriosis; small bowel\n1. Introduction\nEndometriosis is a chronic condition characterized by\nthe presence of endometrial-like tissue outside the uterus,\naffecting up to 15% of women of reproductive age [1]. Clin-\nically, it often presents with pelvic pain, dysmenorrhea,\ndyspareunia, and infertility, with symptoms that typically\nfluctuate in response to hormonal changes [ 1].\nWhen ectopic endometrial tissue involves the gas-\ntrointestinal tract, most commonly the sigmoid colon and\nrectum, it is classified as intestinal endometriosis. This sub-\ntype may present with nonspecific gastrointestinal symp-\ntoms such as abdominal pain, constipation, rectal bleeding,\nand tenesmus [2]. However, due to the considerable overlap\nof these symptoms with other gastrointestinal disorders, in-\ncluding irritable bowel syndrome, inflammatory bowel dis-\nease, and colorectal malignancies, establishing an accurate\ndiagnosis remains challenging [ 3].\nHistopathological evaluation typically reveals en-\ndometriotic lesions composed of endometrial glands and\nstroma, often accompanied by hemorrhage and fibrosis. In\ncases of deeply infiltrative disease, dense adhesions and ex-\ntensive fibrosis may develop, potentially leading to bowel\nobstruction or stricture formation. The extent of intestinal\nwall involvement can vary and may include:\n\n• Serosal involvement, which typically leads to adhesions\nbetween the bowel and adjacent structures, contributing\nto anatomical distortion.\n• Muscularis propria and submucosal involvement, more\ncommonly observed in deep infiltrating endometriosis,\noften leads to fibrosis and luminal narrowing, potentially\nnecessitating surgical intervention.\n• Mucosal involvement, although rare, may clinically and\nendoscopically mimic inflammatory bowel disease or\ncolorectal cancer (Fig. 1). Histologically, it is charac-\nterized by the presence of endometrial glands and stroma\nwithin the mucosa, sometimes accompanied by ulcera-\ntion or bleeding [ 4].\nFig. 1. Intraoperative image of a strictured rectosigmoid\ncolon segment in a patient with postmenopausal intramural\nendometriosis.\nThe reported prevalence of intestinal endometriosis\nvaries widely, ranging from 3% to 37% [5]. Symptoms such\nas dysmenorrhea, dyspareunia, and dyschezia are often sig-\nnificantly alleviated after surgical treatment [6]. Among the\nsurgical approaches, segmental resection is generally pre-\nferred in cases of deep rectal involvement. Although this\ntechnique is associated with higher postoperative complica-\ntion rates, it provides a lower risk of recurrence compared\nto shaving or disc excision procedures [ 7].\nAvailable surgical options for colorectal endometrio-\nsis include shaving, disc resection, and segmental resection.\nSegmental resection is generally indicated for extensive or\ndeep wall infiltration but is associated with an increased\nrisk of complications, including postoperative fever, trans-\nfusion requirements, and rectovaginal fistula formation [8].\nNevertheless, the recurrence rate after segmental resection\nis lower than that of more conservative techniques [ 9].\nLong-term follow-up studies have demonstrated that sur-\ngical treatment significantly improves both symptoms and\nquality of life in patients with rectal endometriosis [ 10].\nIn this study, we retrospectively analyzed cases of in-\ntestinal endometriosis treated surgically across five tertiary\nreferral centers, with a focus on clinical presentation, sur-\ngical approaches, and histopathological findings.\n2. Materials and Methods\nBetween January 2012 and February 2025, patients\nwith intestinal endometriosis who underwent surgery were\nretrospectively evaluated across five tertiary referral cen-\nters: Istanbul Sultan Abdülhamid Han Training and Re-\nsearch Hospital, Izmir Katip Çelebi University, Atatürk\nTraining and Research Hospital, Bakırköy Dr. Sadi Konuk\nTraining and Research Hospital, Başakşehir Çam and\nSakura City Hospital, and Izmir City Hospital.\nAll pathology reports diagnosed as “endometriosis”\nbetween January 2012 and February 2025 were reviewed.\nFrom these, only patients with histopathologically con-\nfirmed intestinal involvement, defined by the presence of\nendometriotic glands and stroma within the bowel wall,\nwere included. Patients with endometriosis confined to\ngenital or other extragenital sites without intestinal involve-\nment were excluded. No additional clinical or radiologi-\ncal criteria were applied for inclusion; patient selection was\nbased solely on pathological confirmation.\nHistopathological Diagnosis\nIntestinal involvement was confirmed on hematoxylin\nand eosin (H&E)-stained sections by the presence of en-\ndometrial glands and stroma within the intestinal wall lay-\ners, including the serosa, muscularis propria, or submucosa.\nCases with involvement limited to the peritoneal surface,\nwithout deeper infiltration into the bowel wall, were ex-\ncluded. Immunohistochemical staining supported the di-\nagnosis, demonstrating estrogen receptor (ER) positivity\nin glandular structures and CD10 (cluster of differentia-\ntion 10) positivity in the surrounding spindle cell stroma.\nPathological evaluations were performed independently at\neach participating center by experienced gastrointestinal\npathologists. Although no central pathology review was\nconducted, all centers adhered to uniform diagnostic crite-\nria and applied immunohistochemistry (ER, CD10, PAX8\n[Paired Box Gene 8]) when necessary, ensuring diagnostic\nconsistency across the study population.\n2\n\n\nTo ensure methodological consistency across the five\nparticipating tertiary centers, a standardized data collection\nform was developed prior to data extraction. This form\nincluded predefined variables such as age, menopausal\nstatus, presenting symptoms, surgical indications, proce-\ndures performed, and complications. Investigators at each\ncenter independently extracted data using the same form,\nand all completed datasets were centrally compiled into\na unified Excel spreadsheet. Any discrepancies were re-\nsolved through cross-checking among investigators and,\nwhen necessary, direct review of surgical or pathology re-\nports. This standardized approach minimized reporting het-\nerogeneity and ensured methodological consistency across\ncenters.\nA comprehensive set of patient data was systemati-\ncally recorded and analyzed, including demographic char-\nacteristics, menopausal status, preoperative symptoms, op-\nerative time (minutes), estimated intraoperative blood loss\n(milliliters), surgical and pathological findings, antibiotic\nregimens, and postoperative complications graded accord-\ning to the Clavien-Dindo classification system. Although\nthe study was conducted across five tertiary centers, stan-\ndardized data collection protocols were applied. Surgical\nindications and procedures followed current clinical guide-\nlines. Pathological assessments were performed by ex-\nperienced gastrointestinal pathologists using routine H&E\nstaining and, when necessary, immunohistochemistry. A\nuniform data collection form was employed across all cen-\nters to ensure consistency in the recorded variables.\nIn our study, to evaluate the effect of surgical site\nand emergency versus elective status on complications, pa-\ntients were categorized into four localization groups: (1)\nappendix, (2) small intestine, (3) colon, and (4) rectum.\nComplication severity was graded using the Clavien-Dindo\nclassification system. Nonparametric tests (Kruskal-Wallis\nH test and Mann-Whitney U test) were applied to as-\nsess differences in complication severity between groups.\nThe relationship between emergency versus elective status\nand complication severity was analyzed using the Mann-\nWhitney U test. For comparisons among localization\ngroups, statistical significance was set at p < 0.05. If the\nKruskal-Wallis test yielded significance, post hoc Dunn’s\ntest was performed for multiple comparisons to identify the\nsource of the difference. In addition, the Chi-square test\nwas used to examine differences in complication rates be-\ntween groups. All statistical analyses were conducted us-\ning SPSS Statistics version 29.0 (IBM Corp., Armonk, NY ,\nUSA).\nThis study was conducted in accordance with the Dec-\nlaration of Helsinki and was approved by the Ethics Com-\nmittee of Izmir Katip Çelebi University (Approval Number:\n0060; dated July 18, 2024). Because this was a retrospec-\ntive analysis using anonymized patient data, the committee\nwaived the requirement for individual informed consent.\nContinuous variables were expressed as mean ± standard\ndeviation (SD) or as median with interquartile range (IQR),\nwhile categorical variables were presented as frequencies\nand percentages (%). American Society of Anesthesiol-\nogists (ASA) scores were recorded to assess preoperative\nhealth status but were not used in subgroup comparisons or\nclinical decision-making.\n3. Results\nA total of 49 patients with histologically confirmed\nintestinal endometriosis were identified, and their medical\nrecords were retrospectively reviewed. All patients pre-\nsented with nonspecific symptoms, including abdominal\npain, rectal bleeding, and constipation.\nThe mean body mass index among postmenopausal\npatients was 24.5 kg/m 2. Patient characteristics, includ-\ning age, menopausal status, surgical setting (emergency\nvs. elective), ASA scores, preoperative diagnosis, type of\nsurgical procedure (open, laparoscopic, robotic), operative\ntime, intraoperative blood loss, antibiotic use, length of hos-\npital stay, postoperative complications (graded using the\nClavien-Dindo classification), follow-up duration, and 30-\nand 90-day readmission rates, are summarized in Table 1.\nThe mean intraoperative blood loss was 30 mL.\nAll patients were evaluated preoperatively by the De-\npartment of Gynecology and Obstetrics. Transvaginal ul-\ntrasonography (TVUS) was performed in all but five cases;\nhowever, none demonstrated findings suggestive of intesti-\nnal endometriosis, highlighting the diagnostic challenges\nand frequent under-recognition of bowel involvement in\nroutine gynecological evaluations. In emergency cases,\nabdominal contrast-enhanced computed tomography (CE-\nCT) was routinely performed. In elective cases, rectal le-\nsions were evaluated with pelvic magnetic resonance imag-\ning (MRI), while sigmoid colon pathologies were typically\nassessed using abdominal CT. Nevertheless, in none of\nthe cases did preoperative imaging indicate endometrio-\nsis. Consequently, preoperative gynecologic consultation\nwas not obtained for any patient. Neither endoscopic ultra-\nsound (EUS) nor positron emission tomography-CT (PET-\nCT) was utilized. All surgeries were performed by gen-\neral surgeons without preoperative multidisciplinary team\n(MDT) involvement. None of the patients had received hor-\nmonal or conservative medical therapy for endometriosis\nprior to surgery. The mean interval between initial imaging\nand surgery was 48.6 ± 12.4 days. In all cases, the diag-\nnosis of intestinal endometriosis was established postoper-\natively through histopathological evaluation, and patients\nwere subsequently referred to gynecology for further man-\nagement. These findings underscore the underdiagnosis of\nbowel endometriosis despite adequate imaging and clinical\nevaluation and highlight the need for heightened awareness\nand multidisciplinary collaboration in suspected cases.\nEmergency surgery was performed in 35 patients\n(71.4%). The types of surgical procedures included:\n3\n\nTable 1. Demographic characteristics and surgical data.\nV ariables V alue\nMenopausal status N (%)\nPremenopausal 41 (83.7%)\nPostmenopausal 8 (16.3%)\nAge (Mean ± SD) 42.4 ± 10.8 years\nEmergency N (%)\nElective surgery 14 (28.6%)\nEmergency surgery 35 (71.4%)\nAcute appendicitis 26\nObstruction 8\nPerforation 1\nOperation time (Median [IQR]) 142.5 (35–240) min\nPreliminary diagnosis N (%)\nRectosigmoid cancer 10 (20.4%)\nAcute appendicitis 29 (59.2%)\nMass in the small intestine 2 (4.1%)\nComplex polyp 4 (8.2%)\nDiverticulitis 4 (8.2%)\nASA N (%)\n1 25 (51%)\n2 22 (44.9%)\n3 2 (4.1%)\nMean hospital stay 4.4 ± 4.5 days\nSurgical Technique N (%)\nOpen 20 (40.8%)\nLaparoscopic 26 (53.1%)\nRobotic 3 (6.1%)\nSurgery N (%)\nResection (colon and rectal diseases) 21 (42.9%)\nAppendectomy (acute appendicitis) 26 (53.1%)\nSmall bowel resection (small intestinal diseases) 2 (4.1%)\nIntraoperative blood loss 30 cc\nAntibiotics used\nCefazolin + ornidazole 7 (14.3%)\nOnly cefazolin 42 (85.7%)\nPostoperative complications (Clavien-Dindo)\n0–No complication 41 (83.7%)\nI–Minor (e.g., wound issues, oral antibiotics) 3 (6.1%)\nII–Pharmacological treatment 2 (4.1%)\nIIIa–Radiologic intervention 2 (4.1%)\nIIIb–Reoperation 1 (2.0%)\nIV–V 0 (0%)\nFollow-up Duration (Median) 30 days (11–702 days)\nReadmission\nWithin 30 days 1 (2.0%)\nWithin 90 days 2 (4.0%)\nAbbreviations: N, number; SD, standard deviation; IQR, interquartile range; ASA, American\nSociety of Anesthesiologists; min, minutes.\n• Anterior or low anterior resection, primarily performed\nfor presumed diagnoses such as rectosigmoid carcinoma,\nrectal polyps, or sigmoid diverticulitis.\n• Right hemicolectomy, conducted in patients suspected\nof having right-sided colon cancer.\n• Appendectomy, performed in cases presumed to be acute\nappendicitis.\n4\n\n\nTable 2. Comparison of postoperative complication rates and Clavien-Dindo scores across different surgical sites.\nGroup (surgical site) Complication rate Median Clavien-Dindo score Notes\nAppendix (Group 1) 19% 0.0 Lowest risk; many emergency appendectomies\nSmall Intestine (Group 2) Intermediate Intermediate —\nColon (Group 3) Intermediate Intermediate —\nRectum (Group 4) 80% 2.0 Highest complication rate\np-value 0.033 (Chi-square) 0.020 (Kruskal-Wallis) Statistically significant difference\n• Small bowel resection, carried out in patients with sus-\npected small intestinal masses on radiological imaging.\n3.1 Postoperative Complications\nPostoperative complications occurred in 8 patients\n(16.3%). These included:\n• 2 cases of postoperative ileus , all successfully managed\nwith conservative treatment.\n• 2 cases of postoperative pneumonia accompanied by\nfever, requiring intravenous antibiotic therapy.\n• 1 pelvic abscess, drained under interventional radiology\nguidance on postoperative day 7.\n• 1 case of postoperative hemorrhage , requiring surgical\nreoperation on the following day.\n• 1 wound dehiscence (eventration) , necessitating early\nsurgical repair.\n• 1 case of subcutaneous fat necrosis with wound dis-\ncharge, managed conservatively.\nNo cases of anastomotic leakage, enteric fistula, or\nstoma-related complications were observed.\n3.2 Notable Cases\nIn one patient, intramural endometriosis was identi-\nfied. A 67-year-old postmenopausal woman underwent\nemergency surgery for a suspected rectosigmoid tumor\ncausing obstruction. Intraoperatively, a stricture was ob-\nserved without a visible tumor. The resected segment ex-\nhibited a 2.5 cm luminal narrowing over a 5 cm length of\nbowel, with 1 cm wall thickening. Histopathological eval-\nuation revealed endometrial glands and stroma localized\nto the muscularis propria. ERs were focally positive, and\nPAX8 was diffusely positive, confirming the diagnosis of\nintestinal endometriosis.\nAnother notable case involved a 41-year-old pre-\nmenopausal woman who underwent urgent low anterior\nresection for suspected rectosigmoid obstruction. A 6\ncm stenotic segment with 1.8 cm luminal narrowing and\nmarked bowel wall thickening was identified. Histopathol-\nogy revealed deep infiltrating endometriosis with transmu-\nral involvement, affecting the mucosa, submucosa, muscu-\nlaris propria, and serosa, closely mimicking a neoplastic le-\nsion. Immunohistochemistry showed diffuse ER and PAX8\npositivity in glandular cells, along with CD10 positivity in\nstromal tissue.\nIn all cases, intestinal endometriosis was not sus-\npected preoperatively and was diagnosed postoperatively\nsolely based on histopathological evaluation. No coexist-\ning pathological conditions were identified in the surgical\nspecimens, and the clinical symptoms were attributed ex-\nclusively to intestinal endometriosis.\nStatistical analyses revealed statistically significant\ndifferences between the surgical localization groups in both\ncomplication severity (Clavien-Dindo score) and complica-\ntion rates. The Kruskal-Wallis H test showed that the dis-\ntribution of complication severity differed significantly be-\ntween the groups ( p = 0.020). Post-hoc analyses showed\nthat this difference was primarily driven by the compari-\nson between the Rectum group (Group 4) and the Appendix\ngroup (Group 1) ( p < 0.01). The Rectum group had a\nsignificantly higher median Clavien-Dindo score (2.0) and\ncomplication rate (80%) compared to the Appendix group,\nwhich had a median score of 0.0 and a complication rate\nof 19%. However, no statistically significant difference in\nClavien-Dindo complication scores was observed between\nthe emergency and elective surgery groups (p > 0.05). This\nfinding is likely because the vast majority (71.4%) of the\nemergency surgery group consisted of appendectomy pro-\ncedures, which carry a relatively low risk of complications.\nThe Chi-square test also confirmed that complication rates\ndiffered significantly between the localization groups ( p =\n0.033). The complication profiles of the Small Intestine\nand Colon groups were intermediate between those of the\nRectum and Appendix groups. A comparative summary\nof complication severity and rates across surgical sites is\nshown in Table 2.\n4. Discussion\nIntestinal endometriosis, particularly in post-\nmenopausal women, poses a significant diagnostic\nchallenge due to its rarity and nonspecific clinical and\nradiological features. This condition often mimics other\ngastrointestinal pathologies, including colorectal carci-\nnoma, inflammatory bowel disease, and diverticulitis,\nthereby complicating preoperative diagnostic accuracy.\nConventional imaging modalities, such as CT, MRI,\nand colonoscopy, frequently fail to detect the disease,\nespecially in early or atypical cases, since the patholog-\nical process typically originates at the serosal surface\nand progresses inward toward the mucosa [ 11]. A no-\ntable finding of our study is the complete absence of\n5\n\npreoperative suspicion of endometriosis in all patients,\nincluding one with intramural endometriosis. Intramural\nlocalization, confined to the muscularis propria without\ninvolvement of the mucosa or serosa, represents one of\nthe most diagnostically challenging forms. Its lack of\nradiological and endoscopic detectability underscores the\nlimitations of current noninvasive diagnostic strategies and\nhighlights the necessity of intraoperative assessment and\nhistopathological confirmation.\nAnother remarkable aspect is the occurrence of in-\ntestinal endometriosis in postmenopausal women, a popu-\nlation traditionally considered hypoestrogenic. Despite the\ncessation of ovarian estrogen production, several mecha-\nnisms may sustain ectopic endometrial activity. Periph-\neral aromatization of androgens in adipose tissue and skin\ncontributes to extragonadal estrogen production, while lo-\ncal estrogen biosynthesis within endometriotic lesions—\nmediated by aromatase expression in stromal cells—plays a\npivotal role in lesion maintenance and progression [ 12,13].\nIn addition, proinflammatory cytokines and growth factors,\nincluding interleukins, prostaglandins, and tumor necrosis\nfactor-alpha, contribute to the persistence of endometriotic\ninflammation and tissue remodeling, even in the absence of\nsystemic hormonal stimulation [ 14]. This complex inter-\nplay of endocrine and paracrine mechanisms may explain\nthe persistence and progression of the disease in this patient\nsubgroup .\nIn our cohort, a substantial proportion of patients, par-\nticularly postmenopausal women, underwent emergency\nsurgical intervention due to acute symptoms, such as\nbowel obstruction or suspected malignancy. These emer-\ngency procedures served a dual purpose: alleviation poten-\ntially life-threatening symptoms and providing a definitive\nhistopathological diagnosis. Intraoperative findings fre-\nquently revealed fibrotic, stenotic bowel segments that had\nbeen misinterpreted preoperatively as neoplastic lesions.\nThe absence of typical risk factors, such as hormone re-\nplacement therapy or a prior diagnosis of endometriosis,\nfurther contributed to diagnostic delays.\nOur findings align with the broader surgical litera-\nture, which emphasizes that procedural complexity is a\nkey determinant of postoperative outcomes. This is par-\nticularly evident in pelvic surgery, where anatomical con-\nstraints markedly increase technical difficulty. Jago et al .\n[15] observed that bowel surgeries, such as rectal resections\nfor endometriosis, carry a significant risk of both short-\nand long-term complications, underscoring the importance\nof meticulous preoperative planning and surgical expertise.\nOur results support this perspective, showing that the inher-\nently higher complexity of rectal procedures was the pri-\nmary factor influencing complication rates, effectively out-\nweighing the effect of surgical urgency. This reinforces the\nprinciple that risk assessment should be procedure-specific\nrather than relying solely on broad classifications, such as\nemergency versus elective status.\nAlthough subgroup analyses demonstrated a statisti-\ncally significant difference in complication rates between\nrectal and appendiceal endometriosis cases, this disparity\nlikely reflects the inherent complexity and technical chal-\nlenges of rectal surgery rather than differences in disease\nbiology. The lower complication rates observed in appen-\ndiceal cases, typically managed with less complex proce-\ndures, may account for this contrast. Given the limited sam-\nple size, these findings should be interpreted with caution\nand considered hypothesis-generating rather than defini-\ntive.\nOverall, the rate of postoperative complications in our\nseries was low, and no cases of long-term bowel dysfunc-\ntion were observed, supporting the feasibility and safety of\nsurgical management even in emergency settings. Never-\ntheless, the requirement for segmental resection in several\npatients underscores the severity of luminal involvement\nand the potential for transmural disease progression in long-\nstanding or undiagnosed cases.\nGiven these findings, clinicians should maintain a\nhigh index of suspicion for intestinal endometriosis in fe-\nmale patients, regardless of age or menopausal status, who\npresent with unexplained gastrointestinal symptoms, recur-\nrent subocclusive episodes, or imaging findings sugges-\ntive of malignancy without confirmatory biopsy. This con-\nsideration is particularly important during diagnostic la-\nparoscopy or laparotomy, where direct visualization may\nprovide the first—and sometimes only—opportunity to\nidentify and resect endometriotic lesions.\nDespite the availability of conventional imaging\nmodalities, including TVUS, abdominal/pelvic CT, and\nMRI, none of the patients in our cohort exhibit a preoper-\native suspicion of endometriosis. This diagnostic gap un-\nderscores the limitations of current techniques, particularly\nin cases lacking classic symptoms or visible pelvic masses.\nContributing factors may include submucosal or intramu-\nral localization, nonspecific radiologic features, and lim-\nited gynecologic assessment in emergency settings. Future\nclinical practice may benefit from incorporating advanced\nmodalities, such as MRI enterography or EUS, when eval-\nuating patients with unexplained gastrointestinal symptoms\nand suspected deep infiltrating endometriosis.\nThis study contributes to the growing body of litera-\nture emphasizing the heterogeneous presentation of intesti-\nnal endometriosis. Previous epidemiological reviews have\nshown that demographic and reproductive factors—such as\nearly age at menarche, short menstrual cycle length, lean\nbody habitus, and parity—may influence the overall risk\nof endometriosis [ 16]. Although our dataset did not allow\ndirect comparison with ovarian endometriosis, these char-\nacteristics may also affect the likelihood of intestinal in-\nvolvement. Unlike prior series that primarily focused on\nreproductive-age women with classic gynecologic symp-\ntoms, our findings highlight that intestinal endometriosis\ncan also occur in asymptomatic or postmenopausal women,\n6\n\n\noften presenting in contexts unrelated to suspected gyne-\ncologic disease. By underscoring this overlooked entity in\natypical clinical scenarios, we aim to enhance diagnostic\nawareness and promote earlier surgical referral when appro-\npriate. Ultimately, a multidisciplinary approach involving\nsurgeons, gynecologists, and pathologists remains essential\nto improve diagnostic accuracy and optimize outcomes in\npatients with suspected or incidentally discovered intestinal\nendometriosis.\nLimitations\nThis study has several limitations. First, its retro-\nspective design introduces the potential for selection and\nreporting bias. Second, although data were collected\nfrom five tertiary centers—increasing the generalizability\nof findings—variations in surgical technique and pathologi-\ncal evaluation may have introduced heterogeneity. Further-\nmore, due to the retrospective nature of the study and data\navailability, the median follow-up duration was limited to\n30 days, which allowed for the assessment of perioperative\noutcomes but prevented evaluation of long-term recurrence\nor functional results.\nThe relatively small sample size over a 13-year period\nreflects the rarity of pathologically confirmed intestinal en-\ndometriosis requiring surgical intervention. Although this\nmay limit statistical power and generalizability, the strict\ninclusion criteria aimed to ensure diagnostic accuracy and\ncohort homogeneity.\n5. Conclusion\nIntestinal endometriosis can present with a wide range\nof nonspecific symptoms and may mimic other gastroin-\ntestinal pathologies, such as malignancy or inflammatory\ndiseases. Our multicenter series highlights the diagnostic\nchallenges of bowel endometriosis, particularly in emer-\ngency surgical settings, where definitive diagnosis is of-\nten established postoperatively through histopathological\nexamination. Increasing clinical awareness, especially in\nreproductive-age women with unexplained gastrointestinal\ncomplaints, may facilitate earlier recognition. A multidis-\nciplinary approach and individualized treatment plans are\nessential to improve outcomes and avoid unnecessary ex-\ntensive surgeries.\nAvailability of Data and Materials\nThe datasets generated and analyzed during the cur-\nrent study are available from the corresponding author on\nreasonable request. All data are stored securely in com-\npliance with ethical guidelines and patient confidentiality\nregulations.\nAuthor Contributions\nNK, FM, and FC designed the research study. NK,\nAUU, SK, HOS, and SB performed the research and col-\nlected the data. MT provided pathological interpretation\nand contributed to histopathological evaluation. FC, EK\nand ÖFO contributed substantially to the conception and\ndesign of the study, supervised surgical management, and\nparticipated in the interpretation of clinical data. SB con-\ntributed to data tabulation and figure editing. All authors\ncontributed to editorial changes in the manuscript. All au-\nthors read and approved the final manuscript. All authors\nhave participated sufficiently in the work and agreed to be\naccountable for all aspects of the work.\nEthics Approval and Consent to Participate\nThis study was approved by the Ethics Committee of\nİzmir Katip Çelebi University in July 18, 2024, with the\ndecision number 0060. As this is a retrospective study\nusing anonymized data, individual informed consent for\nparticipation was not required. However, one intraopera-\ntive image is included in the manuscript, for which written\ninformed consent for publication was separately obtained\nfrom the patient. The study was carried out in accordance\nwith the guidelines of the Declaration of Helsinki.\nAcknowledgment\nWe would like to express our sincere gratitude to all\nthe surgical teams, pathologists, and research coordinators\nat the participating centers for their contributions to data\ncollection and clinical management. We also thank all the\npeer reviewers for their valuable comments and construc-\ntive suggestions during the evaluation process. Special\nthanks to the Department of Pathology at Izmir City Hospi-\ntal for supporting the histopathological review.\nFunding\nThis research received no external funding.\nConflict of Interest\nThe authors declare no conflict of interest.\nReferences\n[1] Christiansen A, Connelly TM, Lincango EP , Falcone T, King C,\nKho R, et al. Endometriosis with colonic and rectal involvement:\nsurgical approach and outcomes in 142 patients. Langenbeck’s\nArchives of Surgery. 2023; 408: 385. https://doi.org/10.1007/\ns00423-023-03095-w .\n[2] Alborzi S, Roman H, Askary E, Poordast T, Shahraki MH,\nAlborzi S, et al . Colorectal endometriosis: Diagnosis, sur-\ngical strategies and post-operative complications. Frontiers in\nSurgery. 2022; 9: 978326. https://doi.org/10.3389/fsurg.2022.\n978326.\n[3] Nezhat C, Li A, Falik R, Copeland D, Razavi G, Shakib A, et\nal. Bowel endometriosis: diagnosis and management. 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