HYDROCOLONIC ULTRASONOGRAPHY IN THE DETECTION OF COLONIC POLYPS AND TUMORS

Background. Hydrocolonic ultrasonography - abdominal ultrasonography i n conjunction with the retrograde instillation of water into the colon - has been advocated as an alternative to colonoscopy for detecting c olorectal polyps and cancer. We conducted a prospective, blinded trial to evaluate the procedure further. Methods. Fifty-two consecutive pat ients (50 men and 2 women; average age, 62 years) who were referred fo r colonoscopy underwent hydrocolonic ultrasonography followed by colon oscopy. The physicians performing colonoscopy were blinded to the ultr asound results. Patients who had a history of colonic polyps or tumors or who had previously undergone flexible sigmoidoscopy or colonoscopy were excluded. Results. Twenty-two patients had normal results on col onoscopy, 26 had polyps, 3 had cancer and polyps, and 1 had cancer alo ne. Twenty patients had polyps less than 7 mm in diameter, eight had p olyps 7 mm or more in diameter, and one had a polyp of unknown size. H ydrocolonic ultrasonography did not detect any cancers and detected on ly one polyp greater than or equal to 7 mm and one polyp <7 mm in diam eter. The overall sensitivity of ultrasonography for identifying any p olyp was 6.9 percent, and for identifying a polyp greater than or equa l to 7 mm, it was 12.5 percent. Ultrasonography suggested the presence of five masses and five polyps that were not confirmed by colonoscopy . Six patients had incomplete ultrasound studies because of discomfort or the inability to retain water. There were two complications: one p atient had two vasovagal episodes, and another had diaphoresis. Conclu sions. Hydrocolonic ultrasonography was less useful than colonoscopy f or detecting colorectal polyps and cancers. The usefulness of the tech nique in screening for colonic polyps and tumors appears to be limited .