Changes in colorectal function in severe idiopathic chronic constipation.

Physiologic studies of colorectal and anal function were performed in 25 adult patients with severe idiopathic long-standing constipation compared with 22 age- and sex-matched normal subjects. Only patients with primary severe idiopathic constipation with no known underlying primary etiology have been studied. No significant changes were observed in the resting or squeeze anal canal pressures. There was indirect evidence that rectal sensation was grossly impaired in 17 of the constipated patients: mean values for constant sensation compared with controls being 269 +/- 21 ml and 136 +/- 10.3 ml, respectively (p less than 0.01). The mean anorectal angles during attempted defecation were significantly less in constipated patients compared with controls (p less than 0.001), and 10 patients were unable to evacuate from the rectum a balloon containing 150 ml of a weak barium suspension. Electromyography of the pelvic floor showed increased puborectalis activity on attempted defecation in 9 subjects. Although there was no significant difference in the basal sigmoid motility index between constipated patients and controls, response to intrarectal bisacodyl (5 mg) was impaired in the constipated group, being 479 +/- 22.1 and 735 +/- 24.7, respectively (p less than 0.01). Transit time was significantly delayed in the constipated patients; the percentage of markers passed by constipated patients after 5 days was 39.0 +/- 6.9 compared with 73.9 +/- 2.8 passed by controls (p less than 0.02). These results imply that there is often a motor abnormality of the pelvic floor and the colon in patients with long-standing chronic constipation.