Physiological changes after postanal repair and parameters predicting outcome.

Nineteen patients have been studied before and 3 months after postanal repair. Physiological parameters have been compared with 16 age- and sex-matched controls. Twelve patients were substantially improved whereas seven obtained no clinical benefit. Pre-operative resting (P less than 0.005), squeeze (P less than 0.005) and strain (P less than 0.005) anal pressures at 2 cm were significantly less than controls. Similarly, pressures during all three events at 4 cm were significantly less than controls (resting P less than 0.05, squeeze P less than 0.005, strain P less than 0.025). Median volume of first leak during saline infusion was significantly less than controls (P less than 0.005) as was the total tolerable volume (P less than 0.005). Videoproctographic parameters which differed significantly from controls included pelvic floor descent at rest (P less than 0.005), during contraction (P less than 0.005) and straining (P less than 0.05); resting and squeeze perineal descent (P less than 0.005); and anal canal length at rest and straining (P less than 0.005). Anorectal angles, rectal compliance, rectal sensation and emptying did not differ from controls. None of these parameters was improved by postanal repair. Patients not improved by operation could be detected pre-operatively by low resting (P less than 0.05), squeeze (P less than 0.025) and strain (P less than 0.05) anal pressure at 2 cm as well as by videoproctographic evidence of increased pelvic floor descent at rest (P less than 0.01), during contraction (P less than 0.005) and straining (P less than 0.005), excessive perineal descent at rest (P less than 0.05), during contraction (P less than 0.05) and during attempted defaecation (P less than 0.05) and a short anal canal at rest (P less than 0.05) and during straining (P less than 0.025).