The ideal lateral internal sphincterotomy: clinical and endosonographic evaluation following open and closed internal anal sphincterotomy.

Objective: To evaluate the relationship between extent of internal sphincter division following open and closed sphincterotomy, as assessed by anal endosonography, with fissure persistence/recurrence and faecal incontinence.

Method: A total of 140 consecutive patients undergoing lateral internal sphincterotomy (LIS) for idiopathic chronic anal fissure were prospectively studied. Preoperative clinical assessment was performed together with a postoperative clinical and endosonographic examination. Three zones of the internal sphincter, identifiable by endosonography, were used to describe the uppermost extent of LIS. Primary end-points were fissure persistence/recurrence and faecal incontinence.

Results: A total of 140 patients, median age 49.5 years (IQR: 38-56 years) were included. Seventy-five (53.6%) and 65(46.4%) patients underwent percutaneous LIS (PLIS) and open LIS (OLIS) respectively. Median follow-up was 21 months (IQR: 14-29 months). Persistence and recurrence rates were 2.9% (4/140) and 5.7% (8/140) respectively. 7.9% (11/140) patients scored > 3 on the Jorge and Wexner Faecal Incontinence scale. PLIS was associated with a trend towards higher fissure persistence/recurrence rates than OLIS (12.0%vs 4.6%, P = 0.141). OLIS was significantly associated with a higher proportion of complete sphincterotomies (CS) than PLIS (56/65 vs 48/75, P = 0.003). A CS was associated with a lower fissure persistence or recurrence rate (1/104 vs 11/36, P < 0.001) but higher incontinence scores (11/104 vs 0/36 cases with Wexner scores > 3, P = 0.042) than following incomplete sphincterotomy. There was a strongly significant increase in incontinence scores (P < 0.001) and decrease in recurrence rates (P < 0.001) with increasing length of sphincterotomy.

Conclusion: We recommend a short and CS using either PLIS or OLIS for the treatment of idiopathic anal fissure.