Topical nitroglycerin versus lateral internal sphincterotomy for chronic anal fissure: prospective, randomized trial

Introduction: Topical nitroglycerin (GTN) is one of the medical treatments of choice in chronic anal fissure. The present prospective, randomized, clinical trial was conducted to study the symptomatic relief, healing, and changes in the maximum anal resting pressure (MARP) in patients with chronic anal fissure comparing topical GTN and lateral sphincterotomy. Methods: Forty consecutive patients with chronic anal fissure were randomized for treatment with either topical GTN or internal sphincterotomy (20 patients in each group). Anal manometry was done before treatment in all patients, and 1 h after application of GTN or sphincterotomy. Patients were followed at 2‐weekly intervals for 6 weeks for symptomatic relief and healing. Results: Both GTN and sphincterotomy brought about a highly significant, but comparable drop in the MARP after treatment (P < 0.0001 in both groups). Sphincterotomy relieved pain much earlier compared to GTN (70% vs 40% at 2 weeks, P = 0.0032); but after 4 weeks of treatment, pain relief in both groups was comparable. Healing in the sphincterotomy group was also earlier than with GTN (55% vs 0% at 2 weeks, P < 0.0001; and 85% vs 30% at 4 weeks, P < 0.0001); but after 6 weeks, healing in both groups was comparable. Sphincterotomy had a significant incidence of minor, short‐term complications; it also required surgical expertise, theatre time, and day‐care beds. Nitroglycerin is safe, with mild and tolerable side‐effects of headache and local burning sensation. Conclusion: Topical GTN should be the initial treatment in chronic anal fissure. Lateral sphincterotomy should be reserved for patients with severe disabling pain (because pain relief is much faster), and for patients not responding to at least 4 weeks of GTN therapy.