Left-sided stenosing lesions in colonoscopy.

Of 2625 consecutive colonoscopic examinations, 122 stenotic lesions interfered with endoscopy. The sigmoid was the most frequent site of stenosis (64%). Of the two types of endoscopic patterns, type A, in which there is an intraluminal protruding mass, is the most frequent, and type B, in which a segment of colon gradually narrows, has intact mucosa. Adenocarcinoma was the most frequent cause of type A (83%), and complications related to diverticular disease (32%) and adenocarcinoma (27%) were most often associated with type B. Colonoscopy, guided multiple biopsies, and brushing cytology gave high diagnostic accuracy for type A lesions. In type B cases, brushings were usually negative.