Colonic Transit Correlates with Frequency of Bowel Movements but Not Stool Form in Patients with Constipation

Abstract

Purpose: Constipation is a prevalent disorder characterized by infrequent bowel movements, hard stools, straining with bowel movements, and/or a sensation of incomplete evacuation. Stool frequency and stool form are often used by clinicians as indicators of colonic transit in constipated patients. The aim of this study was to evaluate the relationship of stool form and frequency with colonic transit in constipated patients. Methods: Patients who underwent whole gut scintigraphy followed by anal manometry for constipation were studied prospectively from January 2008 until May 2010. Each patient completed a questionnaire addressing their number of bowel movements per week and the Bristol stool form scale (BSFS). Whole gut transit scintigraphy measured gastric emptying, small bowel transit, and colonic transit via measurement of a geometric center at 24, 48, and 72 hours. Anal manometry assessed basal anal sphincter pressure (BASP), internal anal sphincter (IAS) relaxation, and balloon expulsion time. Spearman analysis was used to analyze correlations between BSFS, frequency of bowel movements, colonic transit, BASP, IAS relaxation, and balloon expulsion time. Results: A total of 171 patients, 25 males and 146 females, with a mean age of 43.4 years were evaluated. The number of bowel movements correlated with colonic transit at 24 hours (r=0.261, p=0.003), 48 hours (r=0.336, p=0.0001), and 72 hours (r=0.425, p<0.0001). Although a correlation was seen between frequency of bowel movements and BSFS (r=0.435, p<0.001), there was no correlation between BSFS and colonic transit at 24 hours (r=0.070, p=0.422), 48 hours (r=0.131, p=0.139) or 72 hours (r=0.132, p=0.136). Balloon expulsion time, BASP, and IAS relaxation did not correlate with frequency of bowel movements (r=-0.091 [p=0.284], r=0.078 [p=0.334], r=-0.061 [p=0.451]), BSFS (r=0.069 [p=0.438], r=0.201 [p=0.017], r=-0.103 [p=0.220], or colonic transit at 24 hours (r=0.137 [p=0.102], r=0.126 [p=0.115], r=-0.067 [p=0.404]), 48 hours (r=0.103 [p=0.226], r=0.124 [p=0.122], r=-0.058 [p=0.469]) or 72 hours (r=-0.009 [p=0.918], r=0.162 [p=0.044], r=-0.017 [p=0.836]). Conclusion: Frequency of bowel movements correlates with colonic transit in patients with chronic constipation. Interestingly, in this study, stool form did not correlate with colonic transit. Balloon expulsion time, BASP, and IAS relaxtion also had no correlation with frequency or form of bowel movements as well as colonic transit. Thus for the clinician, decreased number of bowel movements, rather than stool form, is associated with slow colonic transit.