Incontinence and rectal prolapse: a prospective manometric study. A prospective, manometric study has been performed on 23 female patients with rectal prolapse and varying degrees of incontinence. Seven of the 14 incontinent patients regained continence after surgery, and a further two patients improved. Improvement in internal and external sphincter function follows correction of rectal prolapse. Preoperative resting anal pressure was significantly higher in continent patients than in incontinent patients (P less than 0.05), as was the maximum voluntary contraction pressure (P less than 0.027). Postoperatively there was a significant increase in the resting anal pressure (P less than 0.0001) and maximum voluntary contraction pressure (P less than 0.003) in the whole group. The preoperative resting anorectal angle was significantly more acute (P less than 0.028) in continent patients than in incontinent patients. There was no significant change in the resting anorectal angle following prolapse repair. Patients who remained incontinent had a significantly lower preoperative resting anal pressure (P less than 0.01) than patients who improved or regained continence. Similarly, maximum voluntary contraction pressure was lower preoperatively in these patients (P less than 0.02). Preoperative resting anal pressure below 10 mm Hg and maximum voluntary contraction pressure below 50 mm Hg are associated with persisting incontinence after surgery. 