Identification of patients likely to benefit from biofeedback for outlet obstruction constipation.

Background: Biofeedback for outlet obstruction constipation has a varying success rate. The aim of this study was to identify which patients are likely to respond to biofeedback. Methods: Thirty patients with severe outlet obstruction constipation were treated by a specialist nurse using three or four sessions of visual and auditory feedback of anal sphincter pressures. All patients were assessed by evacuating proctography, whole-gut transit studies and anorectal physiology before treatment. Results: Two patients did not complete the course of biofeedback. Nine patients improved. Before treatment these patients had predominantly normal anorectal physiology and were all able to open the anorectal angle at evacuating proctography. Nineteen patients did not improve, of whom only three had no measured abnormality other than inability to empty the rectum. Ten of these patients had abnormal anorectal physiology which may have been due to previous vaginal delivery. Conclusion: Biofeedback for outlet obstruction constipation is more likely to be successful in patients without evidence of severe pelvic floor damage.