Can anal manometry predict anal incontinence after fistulectomy in males?

BACKGROUND: Disordered continence is frequently reported after operations for anal fistulae and pre-operative anorectal physiology may be carried out prior to surgery to improve functional outcome. Elderly patients and multiparous females are at higher risk for incontinence, whereas males under 60 have stronger sphincters. The aim of this study was to investigate the predictive role of anal manometry and the causes of postoperative soiling and its effect on the quality of life in males with intact sphincters undergoing excision of either trans or supra sphincteric fistulae.
METHODS: Thirty-eight patients (median age 47 years) were analysed retrospectively. None had previous anal surgery and all were fully continent. Five had Crohn's disease. Anal pressures and rectal sensation were evaluated prior to fistulectomy by means of anal manometry in all cases and after surgery in those who had postoperative incontinence. A cutting seton was used in 17 patients, a rectal advancement flap in 15 and a double rectal-cutaneous flap in six. None had a lay-open. The intersphincteric plane was explored and drained in all cases. A previously described incontinence grading and score was used to assess postoperative soiling. The median follow-up was 22 (range 5-89) months. The patients with postoperative anal incontinence were evaluated with the Gastrointestinal quality of Life Index Questionnaire (0:poor, 4:good) at a median follow-up of 49 months.
RESULTS: Twenty-nine (76%) patients were continent after surgery, whereas 9 (24%) complained of some degree of anal incontinence (minor in 4, severe in 1, the 1-6 incontinence score being 3.7 +/- 1.3 (mean +/- s.d.m.). Their Quality of life score was 3.8 +/- 0.5 (mean +/- sdm). None of them had Crohn's disease, five had frequent diarrhoea, four had a reintervention for either anal fissure or recurrent fistula (two), three had a postseton anal deformity. No difference was found between continent and incontinent patients as far as pre-operative anal pressures were concerned, but the maximum rectal volume threshold was significantly higher in incontinent patients, 165 +/- 67 vs. 123 +/- 49 ml of air (P = 0.04).
CONCLUSIONS: Sphincter division, diarrhoea and anal deformity may cause soiling after fistulectomy in males and it does not severely affect quality of life. Surgery rather than manometry may predict it and rectal sensation may play a role which needs further investigation.