Anal manometric parameters: predictors of outcome following anal sphincter repair?

Controversy exists over the utility of manometry in the management of fecal incontinence. In light of newer methods for the management of fecal incontinence demonstrating favorable results, this study was designed to evaluate manometric parameters relative to functional outcome following overlapping sphincteroplasty. Twenty women, 29 to 84 years of age (mean age 50 years), with severe fecal incontinence and large (>or=50%) sphincter defects on ultrasound were studied. All participants underwent anal manometry (mean resting pressure, mean squeeze pressure, anal canal length, compliance), pudendal nerve terminal motor latency (PNTML) testing, and completed the American Society of Colon and Rectal Surgeons fecal incontinence severity index (FISI) survey before and 6 weeks after sphincter repair. Statistical analysis for all data included the Wilcoxon rank-sum test, Mann-Whitney test, and Spearman's correlation. Significant perioperative improvement was seen in the absolute resting and squeeze pressures and anal canal length. Overlapping sphincteroplasty was also associated with significant improvement in fecal incontinence scores (FISI 36 vs. 16.4; P=0.0001). Although no single preoperative manometric parameter was able to predict outcome following sphincteroplasty, preoperative mean resting and squeeze pressures as well as anal canal length inversely correlated with the relative changes in these parameters achieved postoperatively. These findings suggest that either the physiologic parameters studied are not predictive of functional outcome or the scoring system used is ineffective in determining function. The perioperative paradoxical changes in resting pressure, squeeze pressure, and anal canal length would support the use of overlapping sphincteroplasty in patients with significant sphincter defects and poor anal tone.