Patterns of Bowel Invisible Microscopic Endometriosis Reveal the Goal of Surgery: Removal of Visual Lesions Only.

STUDY OBJECTIVE: To document the presence of bowel invisible microscopic endometriosis implants and their relationship with deep endometriosis macronodule infiltrating the bowel.

DESIGN: A series of consecutive patients with deep endometriosis infiltrating the rectum and/or sigmoid colon (Canadian Task Force classification II-2).

SETTINGS: A university referral center.

PATIENTS: Ten patients managed by colorectal resection.

INTERVENTIONS: A microscopic study of endometriotic foci of the bowel involving 3272 microsection slides was established using a unique method of step serial sections using combined transverse and longitudinal macrosection. Two-dimensional reconstruction based on slide scanning highlighted the presence and localization of the deep endometriosis macronodule in contrast with bowel invisible microscopic endometriosis microimplants.

MEASUREMENTS AND MAIN RESULTS: The distance separating the microimplants and the nodule and their histologic characteristics. The mean length of the colorectal specimens was 91 ± 19 mm. The maximum distance between the farthest microimplants was 7.2 cm. The maximum distance from the macroscopic nodule limit to the farthest microimplant was 31 mm. Bowel invisible microscopic endometriosis microimplants presented with similar features independently of the type of spread. They had an active appearance including stroma and glands, were sometimes decidualized, and were free of fibrosis. They were found on the distal/rectal limit of the specimen in 3 patients and on both limits (distal/rectal and proximal/sigmoid colon) in 1 patient.

CONCLUSION: Invisible microscopic endometriosis implants surround the bowel macroscopic endometriosis nodule at variable distances, suggesting that complete surgical microscopic removal may be a challenging goal. These results may help to reconsider the principles and feasibility of the surgical management of bowel endometriosis.