A Cochrane review included 24 studies with a total of 3475 subjects. Anal stretch has a higher risk of fissure persistence than internal sphincterectomy (OR 1.55, 95% CI 0.85 to 2.86; 7 studies, n= 493) and also a higher risk of minor incontinence than sphincterectomy (OR 4.03, 95% CI 2.04 to 7.96; 7 studies, n=493). After exclusion of two studies causing heterogeneity, the overall effect for efficacy favoured sphincterectomy (OR 3.35, 95% CI 1.55 to 7.26). Open and closed partial lateral internal sphincterectomy show little difference both in fissure persistence and risk of incontinence.
Author's comment: Anal stretch and posterior midline internal sphincterotomy should probably be abandoned in the treatment of chronic anal fissure in adults.