The water jet deformation sign: a novel provocative colonoscopic maneuver to help diagnose an inverted colonic diverticulum.

Colonoscopic differentiation of an inverted colonic diverticulum from a true colonic polyp is important because a true colonic polyp usually requires colonoscopic snare polypectomy or at least biopsy, whereas these maneuvers are contraindicated for an inverted diverticulum due to the risk of colonic perforation. Previously described diagnostic maneuvers to evert an inverted diverticulum include probing it with a closed biopsy forceps or intraluminal air insufflation during colonoscopy. On colonoscopy, a 59-year-old female had two intraluminal colonic projections. Probing these projections and using air insufflation failed to indent or evert them. Spraying these lesions with a water jet, however, flattened or partly everted them. This novel maneuver provided conclusive evidence that these intraluminal projections represented inverted diverticula. The proposed pathophysiology is that water pressure causes an inverted diverticulum to indent or evert due to its thin wall. The currently reported maneuver may be easier and safer than probing an inverted diverticulum with biopsy forceps and may prove a more reliable diagnostic maneuver than air insufflation.