Fig. 11
a The rectum and its “peri-catheter” segment need special attention! Three-dimensional view of the anal margin shows interpretation is hampered by the rectal catheter (black arrow). The impression of the inflated balloon on the rectal wall is nicely appreciated (white arrows). A flat luminal defect is detected at the level of the anal margin, abutting the rectal catheter (white arrowhead). b, c The corresponding prone view after deflation of the balloon of the rectal catheter shows a large sessile polypoid defect (white arrowhead) against the rectal catheter (black arrow) confirmed on 2D as a solid lesion >10 mm, prompting optical colonoscopy