Post-anal repair

Abstract

The post-anal operation was devised by Parks in 1975 [1] to treat patients with idiopathic faecal incontinence (IFI). The principles of the procedure are as follows. Under normal circumstances the angle formed by the junction of the anal canal with the rectum is maintained by the puborectalis muscular sling. The angulation allows the anterior rectal wall to act as a flap valve (Figure 1), and any rise in intra-abdominal pressure forces the mucosa against the upper anal canal and therefore effectively closes it. In idiopathic faecal incontinence the puborectalis is partially or completely denervated and this results in a widened ano-rectal angle and a shortening of the anal canal. As a consequence the flap valve mechanism fails to function satisfactorily and incontinence occurs.