A review of the literature is summarized in Table 4.2 and the quality evaluated using the GRADE system. The studies in the literature are all retrospective small studies with little power and no standardization of outcomes. Only a single study compared botulinum toxin (Botox) to LIS after failure of medical management. D’Ugo et al compared Botox with or without fissurectomy to LIS. However, in patients with confirmed CD, Botox was performed instead of LIS and therefore there is no comparison between Botox and LIS in known CD patients [2]. Lozynskyy et al reported a 75 % healing rate with medical management in CD patients and reported they had not performed surgical treatment of a fissure associated with CD in the last 5 years of their study [7]. Fleshner et al reported a 50 % healing rate with medical fissure management. They then compared fissure healing rates when patients underwent anorectal procedures versus bowel resection for proximal disease. They showed an 88 % healing rate with anorectal procedures (LIS, fissurectomy) versus 43 % with proximal bowel resection for active ileal or colonic CD [8].

Several additional retrospective studies have been performed but very little outcome data exists. For example, Wolkomir et al evaluated 25 CD patients undergoing 27 procedures for anal fissure. However, they did not directly report on the healing or complication rates in their study. They did describe a mean follow up of greater than 7 years and noted that 22 patients had a healed wound by 2 months; however, 11 patients subsequently developed anorectal pathology of whom three developed recurrent fissure [9]. Similarly, Sangwan et al studied 21 patients with anal fissure of whom six underwent LIS and one underwent fissurectomy. However, again, no outcome data was reported in this study [10].