Gastrointestinal symptoms in endometriosis: accompanying with the main disease or rectosigmoid involvement

Gastrointestinal (GI) symptoms are frequently reported in women with endometriosis, but whether these symptoms reliably reflect rectosigmoid deep infiltrating endometriosis (DIE), rather than representing a separate and overlapping symptom burden, has not been directly tested. To investigate the prevalence of rectosigmoid involvement in women with endometriosis, evaluate associated GI symptoms, and examine the relationship between rectosigmoid involvement, symptom profiles, and lesion size. This cross-sectional study included 200 women diagnosed with endometriosis who presented to the endometriosis clinic at Imam Reza Hospital, Mashhad, Iran, between 2019 and 2022. Participants underwent transvaginal or transrectal ultrasound, and MRI when indicated, to assess bowel involvement. Primary outcomes included the prevalence and severity of GI and pain-related symptoms. Associations between rectosigmoid involvement, GI symptoms, and nodule size were analyzed using chi-square, Fisher’s exact, t-test, or Mann–Whitney tests, as appropriate. Rectosigmoid involvement was identified in 70 women (35.0%), predominantly affecting the rectum (98.6%). Dysmenorrhea (96.5%) was the most common pain symptom, followed by dyspareunia (68.5%) and non-cyclic pelvic pain (60%). Among GI symptoms, bloating (60.5%), diarrhea (52%), and constipation (51%) were most prevalent. While 89.5% of participants reported at least one GI symptom, only rectal bleeding showed a significant association with rectosigmoid involvement ( P = 0.021). Patients with GI symptoms had smaller rectosigmoid nodules (mean size 23.5 ± 11.9 mm) compared with those without GI symptoms (37.2 ± 12.2 mm; P = 0.004). Across the entire cohort with rectosigmoid involvement, the mean nodule size was 25.4 ± 12.8 mm (median 20.5 mm). Nodule size was not significantly correlated with specific symptom types. GI symptoms are highly prevalent among women with endometriosis but are not reliable indicators of rectosigmoid involvement. Cyclic rectal bleeding remains a strong clinical marker of rectal DIE and should prompt detailed imaging. Lesion size influences the presence of GI symptoms but does not predict their type.