[The colonoscopic characteristics of colorectal endometriosis: a single-centered retrospective study].

Objective: To reinforce the awareness of colorectal endometriosis (EM) in colonoscopy examination. Methods: Patients diagnosed as colorectal EM at Peking Union Medical College Hospital between February 2002 and February 2017 were enrolled in this study. The clinical characteristics and endoscopic features of EM lesions were summarized and compared between pathologically positive group and negative group. Results: A total of 34 cases were included with average age of (38.3±8.9) years old. All EM lesions located within rectum and sigmoid colon. The endoscopic lesions manifested as protrusion in 21 cases (61.8%) and protrusion-depression in 13 cases (38.2%), local stenosis in 8 cases (23.5%); erosive surface in 33 cases (97.1%) with local spontaneous hemorrhage in 4 cases (11.8%); nodal surface in 23 cases (67.6%), and lymphangiectasis base in 9 cases (26.4%). Endoscopic biopsy specimens were obtained in all cases with average 3 (2, 4) pieces. Positive results were found only in 4 patients (11.8%) with 3 endometriosis and one (endometrial) adenosarcoma. Compared with negative group, spontaneous hemorrhage was more frequent in positive group (2/4 vs. 2/30, P=0.013). Mean biopsy sample number was significantly larger in positive group (5 vs. 3, P=0.004). Conclusions: Colorectal endometriosis is mostly located within rectosigmoid region. Endoscopic features mainly include protrusion or protrusion-depression lesions with erosive and nodular surface, or local stenosis. Spontaneous hemorrhage under colonoscopy yields higher positive rate for biopsy, thus increasing biopsy sample numbers may improve pathology results.