Rectosigmoid Localization of Radiopaque Markers for Identifying Defecation Disorders in Patients With Chronic Constipation: A Retrospective Cohort Study

BACKGROUND/AIMS: Defecation disorders (DD) are part of the spectrum of chronic constipation with outlet obstruction. Although anorectal physiologic tests are required for the diagnosis of DD, these tests are not available in many institutions. This study aims to investigate the predictivity of DD using rectosigmoid localization of radiopaque markers in a colonic transit study. METHODS: A total of 169 patients with refractory constipation with a mean age of 67 years were studied. All patients underwent anorectal manometry, a balloon expulsion test, and a colonic transit study. Barium defecography was performed if needed. The relationship between DD diagnosed by these anorectal tests and the rectosigmoid accumulation of markers was examined. RESULTS: Seventy-nine (46.7%) patients were identified to have DD based on anorectal test combinations. Rectosigmoid accumulation of markers was observed in 39 (23.1%) patients. The sensitivity and positive predictive value of rectosigmoid accumulation for identifying DD were 31.6% and 64.1%, respectively. Rectosigmoid accumulation provided poor discrimination of DD from normal transit constipation, at a specificity of 82.1% but with a sensitivity of only 10.6%. In discriminating DD from slow transit constipation, rectosigmoid accumulation was found to be useful with a positive likelihood ratio of 5.3. CONCLUSIONS: Rectosigmoid accumulation of markers can differentiate DD from slow transit constipation. However, non-rectosigmoid accumulation does not exclude the presence of DD.