Evaluation of postoperative damage to anal sphincter/levator ani muscles with three-dimensional vector manometry after sphincter-preserving operation for rectal cancer.

Abstract

The aim of this study was to examine correlations between pressure profile of the anal canal and postoperative defecatory disorder after sphincter-preserving operation (SPO) for rectal cancer. Using three-dimensional vector manometry, pressure profile and length of the anal canal were evaluated more than 1 year after SPO according to operation method and degree of postoperative defecatory function in 53 patients with rectal cancer. Compared with high anterior resection as a control, the anal canal was shorter in operations with a pelvic floor maneuver, namely, low anterior resection, ultra-low anterior resection, and intersphincteric resection. Patients with postoperative defecatory disorder showed significantly shorter anal canal length than patients with fair function. Length of the circular high-pressure zone (> or = 20 mmHg) < 20 mm in the resting state was a strong predictor of severe postoperative defecatory malfunction, with Wexner score> or =10. Operative maneuvers at the pelvic floor during SPO for rectal cancer may damage anal sphincter or levator ani muscles. The circular high-pressure zone can be measured only by three-dimensional manometry and may offer a useful indicator of sphincter damage after SPO for rectal cancer.