COMPARISON OF 2 TECHNIQUES OF TRANSRECTAL ULTRASONOGRAPHY FOR THE ASSESSMENT OF LOCAL EXTENT OF POLYPOID TUMORS OF THE RECTUM

The capability of transrectal ultrasonography (TRUS) to differentiate between benign and malignant rectal polyps was evaluated. Digital palp ation and sigmoidoscopy were followed by TRUS with a 7.5-MHz linear-ar ray transducer, in a blinded design. In the second part of the study t he procedure was extended with an acoustic window system (AW), prevent ing compression of the polyp. Pathological examination after surgical resection was used for definitive diagnosis in 110 polyps. Digital exa mination detected 10 of 22 carcinomas within adenomas, compared with 1 9 by TRUS (P<0.01). However, TRUS falsely indicated 20 of 49 adenomas to be carcinomas, compared with 4 out of 49 by digital examination (P< 0.001). TRUS combined with AWS detected 23 of 24 carcinomas, and gave a false positive result in only 3 of 26 benign polyps. The results sug gest that the best way to discriminate between benign and malignant re ctal polyps is to combine TRUS with AWS.