EP758 - Colonoscopic findings in patients with rectal endometriosis diagnosed by three-dimensional anorectal ultrasound

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Purpose/Background: The role of colonoscopy in evaluating intestinal involvement by endometriosis is controversial due to the primarily extrinsic nature of the lesions. Additionally, symptoms in patients with endometriosis affecting the rectosigmoid region can resemble those of other intestinal diseases, which must be excluded for appropriate treatment. This study aims to present the incidence of colonoscopic findings in patients with rectosigmoid endometriosis diagnosed via three-dimensional anorectal ultrasound (3DUS).

Methods/Interventions: This prospective study was conducted from February 2007 to August 2024, involving women with a clinical and ultrasound diagnosis of rectal endometriosis confirmed through 3DUS. A total of 836 patients, referred by the gynecology team with suspected intestinal involvement, were included. For the detection of endometriotic foci in the rectum, 3DUS was performed. Patients with positive findings were referred for combined surgery with gynecology and coloproctology specialists.
Patients presenting symptoms such as pain during defecation, incomplete evacuation, diarrhea, constipation, or rectal bleeding were referred for colonoscopy to differentiate between endometriosis and other intestinal diseases. Colonoscopies were performed under sedation, following anterograde colon preparation, by a team of endoscopists.
In addition to unrelated findings, signs of endometriotic lesions, such as extrinsic compression at the rectosigmoid junction, hypervascular areas, and nodules in the descending colon, were evaluated. The endoscopists were blinded to other patient exams. Colonoscopic findings were compared with 3DUS results, previously validated for detecting endometriotic foci in the rectal wall. Patients who did not consent or had incomplete records were excluded. Informed consent was obtained from all participants, and the study was approved by the local ethics committee. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for colonoscopy in diagnosing intestinal endometriosis compared to 3DUS.

Results/Outcomes: Of the 836 patients evaluated by 3DUS, 392 underwent colonoscopy. The average age was 43.4 years. Colonoscopy results were normal in 290 cases or showed findings unrelated to endometriosis, such as colitis, polyps, or diverticular disease, in 59 cases. In 43 patients, colonoscopy showed alterations suggestive of endometriosis, including extrinsic compression at the rectosigmoid junction, hypervascular areas, and nodules in the descending colon.
Colonoscopic findings suggestive of intestinal endometriosis were identified in 38 out of 392 patients (9.7%) diagnosed with rectal endometriosis via 3DUS. This could be attributed to the study being conducted in a reference center for intestinal endometriosis. Sensitivity, specificity, PPV, and NPV of colonoscopy were 38%, 51%, 47%, and 16%, respectively.

Conclusion/Discussion: The incidence of colonoscopic findings in patients with rectosigmoid endometriosis diagnosed through 3DUS was low. However, colonoscopy remains valuable in the differential diagnosis of other intestinal diseases necessary for appropriate treatment.