Chronic idiopathic constipation: the importance of transit time studies

Chronic idiopathic constipation includes a very heterogeneous group of alterations which cannot be correctly defined only by their clinical appearance and require an examination of the colonic transit time. This test is performed by using a specific number of radiopaque markers and a fixed number of X-ray observations. By means of transit time study, we can classify the constipated patients into 4 groups: a) patients with stasis in the right colon (17-53% of cases) which implies an alteration of propulsive forces or absence of mass movements and segmentary motor activity; b) stasis in the left colon (13-27% of cases) which could be due to a "reflux" of colonic contents or to a hyperactive sigmoid; c) rectosigmoid stasis (20-33% of cases) which is secondary to a megarectum. Internal anal sphincter (IAS) and/or external anal sphincter (EAS) function failure and d) normal transit time (greater than 40 of cases) which is commonly due to psychological problems or to a low-fiber-content diet. We can conclude that transit time study is not necessary in mild constipation, but it is advised for those patients who do not respond to standard medical therapy or when surgery is being contemplated.