A study of fecal incontinence in patients with chronic anal fissure: prospective, randomized, controlled trial of the extent of internal anal sphincter division during lateral sphincterotomy.

BACKGROUND: Troublesome fecal incontinence following a lateral internal sphincterotomy is often attributed to faulty surgical technique. However, it may be associated with coexisting occult sphincter defects. Whether continence is related to the extent of sphincterotomy remains debatable. The aim of the study is to identify fecal incontinence related to chronic anal fissure before and after lateral internal sphincterotomy and its relationship to the extent of internal anal sphincter division.
METHODS: One hundred eight patients with chronic anal fissure were prospectively studied before and after lateral internal sphincterotomy. A questionnaire was completed for each patient before and after surgery with regard to any degree of fecal incontinence. Fecal incontinence severity index was assessed using the Cleveland Clinic Incontinence Score. The patients with preoperative perfect continence were randomized into two groups (46 patients in each group): Group 1 underwent traditional lateral internal sphincterotomy (up to the dentate line) and Group 2 were underwent a conservative internal anal sphincterotomy (up to the height of the fissure apex or just below it).
RESULTS: Minor degrees of incontinence were present before surgery in 16 patients (14.8%). Results of the randomized trial revealed that temporary postoperative incontinence was newly developed in 6/92 of patients (6.52 %) who did not have it before surgery. Five of the six (10.86%) were in Group 1 one (2.17%) was in Group 2 (p = 0.039). Persistent incontinence occurred in two in Group 1 (4.35%). All of them were females. All have had a history of one or more vaginal deliveries.
CONCLUSION: A mild degree of fecal incontinence may be associated with chronic anal fissure at presentation rather than as a result of internal sphincterotomy. Troublesome fecal incontinence after lateral internal sphincterotomy is uncommon. Sphincterotomy up to the dentate line provided faster pain relief and faster anal fissure healing, but it was associated with a significant postoperative alteration in fecal incontinence than was sphincterotomy up to the fissure apex. Care should be exercised in female patients with a history of previous obstetric trauma, as internal anal sphincter division may further compromise sphincter function.