Rectal compliance in the assessment of patients with fecal incontinence.

Rectal compliance (dV/dP) was studied in 31 patients with fecal incontinence, 8 patients with constipation, and 16 control subjects. Patients with fecal incontinence experienced a constant defecation urge at a lower rectal volume and also had a lower maximal tolerable volume and a lower rectal compliance than control subjects (median 126 vs. 155 ml, 170 vs. 220 ml, and 9 vs. 15 ml/mm Hg, respectively; P less than 0.05). Constipated patients had a higher constant defecation urge volume and maximal tolerable volume than controls (median, 266 ml and 300 ml; P less than 0.05). There was no differences in the parameters between patients with idiopathic fecal incontinence and patients with incontinence of traumatic origin, indicating that a poorly compliant rectum in patients with fecal incontinence may be secondary to anal incontinence due to the lack of normal reservoir function.