Physiology of refractory chronic constipation.

OBJECTIVE: Investigators suggest three distinct pathophysiologies for patients with constipation symptoms: 1) slow colon transit, 2) irritable bowel syndrome (IBS), and 3) pelvic floor dysfunction (PFD). Our aim was to determine the prevalence of the three types of constipation pathophysiology, the degree of overlap, and what interactions exist between pathophysiologies.
METHODS: Constipated patients refractory to fiber (n = 131) underwent regional colon transit studies, anorectal manometry/EMG, measurement of rectal compliance, and rectal sensory testing. Correlations were performed examining interactions between the above measures.
RESULTS: Visceral hypersensitivity (typical of IBS) was found in 58%, slow colonic transit in 47%, PFD in 59%, and no physiological abnormalities were detected in 24%. Slow transit and visceral hypersensitivity overlapped in half of each group. PFD physiology was found in approximately half of each of the subgroups. There was no correlation between PFD physiology and rectosigmoid transit, total colon transit, or any other physiology. There were no correlations between slow transit and visceral hypersensitivity. Visceral hypersensitivity did correlate with increased rectal compliance, suggestive of increased accommodation reflexes in IBS.
CONCLUSIONS: At a tertiary center, slow transit physiology and visceral hypersensitivity typical of IBS are equally common and overlap heavily in constipated patients. PFD physiology does not correlate with slower rectosigmoid colon transit, and is seen equally in all subgroups. No abnormalities were found in 24% of patients. We therefore identify four subgroups in constipation: IBS, slow transit, both, and neither.