IRCT20210919052515N6 IRCT 2025-06-20 Oroumia University of Medical Sciences Comparison of the two methids of conventional internal partial sphincterotomy and tailored sphincterotomy of string suture anoscope in chronic anal fissure surgery Comparison of the results of chronic anal fissure surgery between conventional internal partial sphincterotomy and tailored sphincterotomy of string suture anoscope 2025-07-23 anticipated 60 Complete https://irct.ir/trial/83962 interventional Randomization: Randomized, Blinding: Single blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Randomization description: Patients will be divided into two methods of surgery using block randomization based on generated numbers by random allocation software. So that, in this software, the number of groups and the total number of the sample size will be entered and then in the block section, the block randomization method will be implemented. Patients will be allocated to two groups based on generated numbers, Blinding description: The study will be conducted as a single-blind clinical trial. The patient will be blinded about surgery methods. N/A Chronic anal fissure. Intervention 1: Intervention group: In tailored Sphincterotomy group , a No. 34 purse-string anoscope will be inserted and rotated circumferentially. Any areas of tightness will be incised using electrocautery. The fissure will be assessed, and thickened edges or apical skin tags (if present) will be excised. The surgeon will ensure that the electrocautery does not extend beyond the dentate line. The extent of sphincterotomy will be precisely adjusted based on fissure height. Intervention 2: Control group: . In conventional partial Sphincterotomy, 30% of the exposed internal sphincter will be cut. The incision site will be repaired with absorbable sutures and dressed. No - There is not a plan to make this available Justification or reason for not sharing IPD is No further information available.