The type of colonic imaging (radiological vs colonoscopic) for evaluating symptomatic patients without evidence of bleeding in both an efficacious and cost-conserving manner has become a very debated issue. In a randomized, controlled clinical trial, the authors hoped to examine the prevalence of neoplasm and the effectiveness and cost-effectiveness of initial diagnostic strategies of colonoscopy versus flexible sigmoidoscopy and air contrast barium enema in patients without evidence of intestinal bleeding. One hundred forty-nine patients over the age of 40 with symptoms suggestive a colonic disease without evidence of bleeding (no hematechezia, negative test for fecal occult blood, and normal serum hemoglobin) were randomized to undergo either initial colonoscopy or flexible sigmoidoscopy plus barium enema. Patients with incomplete lower GI tests were referred for the corresponding alternative imaging modality. Cost analyses using sensitivity analysis were performed. Baseline information with respect to age, race, sex, inpatient status, reason for referral, mean weight loss, hemoglobin, blood urea nitrogen, and albumin were similar in both groups. Eighteen patients (24%) who initially received air contrast barium enema and flexible sigmoidoscopy then required colonoscopy, whereas only five patients (6%) who initially underwent colonoscopy first required air contrast barium enema plus flexible sigmoidoscopy. The study found that: a) The prevalence of cancer in the study was low (one of 149 patients); b) initial colonoscopy detected more persons with adenomas than that of air contrast barium enema plus flexible sigmoidoscopy (23 of 75 patients vs 13 of 74 patients, odds radio, 2.07, CI,0.90-4.92; this approached significance); and c) air contrast barium enema plus flexible sigmoidoscopy detected more diverticulosis (46 of 74 patients vs 31 of 75 patients, odds ratio, 0.41, 95% CI, 0.21-0.87). The significant conclusions were that patients undergoing flexible sigmoidoscopy plus air contrast barium enema were more likely to undergo alternative procedures and that sensitivity analysis suggested that, for most areas in the United States, initial colonoscopy would be more cost-effective for the outcome of detection of adenomas (1).