Follow-up study after colorectal polypectomy. The predictive value of a negative double-contrast barium enema.

In this study the predictive value of a negative double-contrast barium enema for colonic polyps has been calculated as the ratio of the number of true negative radiologic examinations to the total number of negative radiologic examinations. The total number of negative double-contrast barium enemas for polyps of the colon was 357 in 228 consecutive patients with previous or suspected neoplastic colonic polyps examined in the period 1977-84. The predictive value of a negative double-contrast barium enema for all colonic polyps regardless of size was 87% (95% confidence interval, 84-91%). The corresponding predictive value of a negative result for polyps larger than 10 mm in diameter was 98% (95% confidence interval, 97-100%). Polyps that had not been detected by radiography were removed by colonoscopy, and 85% of them were available for histological examination. No cancers were found. The polyps were primarily neoplastic, but metaplastic and juvenile polyps were also ascertained.