Physiologic variables that predict the outcome of treatment for fecal incontinence

Identification of physiologic factors that predict response to fecal incontinence therapy would be helpful in choosing the optimal treatment and advising patients on the likelihood of a successful outcome. However, few physiologic parameters have been consistently identified as important in predicting response to either biofeedback or surgery. The process of isolating these factors has been hampered by heterogeneity in the definition of fecal incontinence, lack of consensus on what constitutes a successful outcome, lack of follow-up data, variations in the way "standard" treatments are implemented, and lack of properly powered randomized controlled trials. Among the physiologic variables that studies have generally found to be predictive of successful outcomes in biofeedback treatment are the threshold for external anal sphincter contraction after treatment, the inclusion of sensory training in treatment, and a reduction in volume for the first sensation after treatment. Factors that have not been found to be important in predicting outcome following biofeedback retraining include the duration of fecal incontinence, pudendal nerve damage, patient age, symptom severity, pretreatment anal canal pressures, and results of anal ultrasonography. The presence of some degree of anorectal sensation is the only preoperative assessment that has been found to be predictive of response to surgical therapy. It is recommended that outcome measures for fecal incontinence be more clearly defined, that future biofeedback studies elaborate the predictive value of pretreatment anorectal sensation and the response to sensory retraining, and that postsurgical measurements such as anal squeeze pressure and sphincter length be taken into account.