Post written by Bo Sun, MD, from the Department of Gastroenterology, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.

This case was a 40-year-old woman with a 2-month history of increased bowel movements and feelings of incomplete evacuation. Her colonoscopy detected a rectal submucosal elevation with unrevealing biopsy results. Pelvic MRI suggested a rectal endometriosis but pathologic diagnosis was needed. Therefore, EUS and EUS-guided fine-needle aspiration (EUS-FNA) were performed, and histopathology confirmed the diagnosis.

Deep pelvic endometriosis often affects the rectum or distal sigmoid colon, which should be listed in differential diagnosis when a rectosigmoid submucosal elevation is observed in a woman of reproductive age. Compared with pelvic MRI, EUS is more sensitive in the diagnosis of rectosigmoid involvement if pelvic endometriosis is highly suspected. In addition, EUS, when feasible, can be performed right after colonoscopy or sigmoidoscopy. EUS-FNA can also be considered during the same procedure for tissue diagnosis. However, EUS video of rectal endometriosis is rare in the literature.

This video case report demonstrated the typical EUS features of rectal endometriosis, which is an irregularly shaped mass with a hypoechoic heterogeneous echo pattern infiltrating the intestinal wall or even surrounding organs. To acquire enough tissue, a 19-gauge FNA needle was selected to puncture the lesion.

Although EUS-FNA has often been performed for cytopathologic diagnosis of rectosigmoid endometriosis, the optimal number of needle passes hasn’t been standardized. It has been suggested in the literature that more than 2 or 3 passes are required. Regarding the type of needle, it would be interesting to compare the diagnostic efficiency of FNA needles with that of newly developed FNB needles, which may be more effective to acquire core tissue.  

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