Chronic anal fissure treatment using lateral internal sphincterotomy without excision: prospective randomized study (NCT05117697)

AIM: to assess the outcomes of chronic anal fissure treatment using lateral internal sphincterotomy with and without fissure excision. PATIENTS AND METHODS: a prospective, single-center, randomized study included 107 patients with chronic anal fissure (CAF) older than 18 years, without severe comorbidities, rectal fistulas, grade 3–4 hemorrhoids, or clinical manifestations of anal sphincter insufficiency (ASI) from October 2021 to October 2023. Patients were randomized using a random number generator into two groups: 56 patients in the main group underwent lateral internal sphincterotomy (LIS), and 51 patients in the control group underwent LIS combined with fissure excision (LIS + FE). Immediate results were analyzed per protocol in 50 patients per group. Late outcomes were assessed in 44 patients in the main group and 43 patients in the control group. Primary endpoint: epithelialization of the defect on the 60th day after surgery. Secondary endpoints: epithelialization of the defect on the 15th, 30th, and 45th days postoperatively, incidence and structure of complications, pain syndrome (VAS from day 1 to day 60), profilometry indicators on the 30th, 60th, and 365th days postoperatively, time of temporary disability, incidence of ASI on the 30th, 60th, and 365th days postoperatively (Wexner's scale), and recurrence rate. RESULTS: by day 60, the anal fissure had epithelialized in 47/50 (94%) patients in the main group, while the postoperative wound had healed in 48/50 (96%) patients in the control group (p = 1). On days 15, 30, and 45, the epithelialization rate of the anal fissure was significantly higher than that of the postoperative wound. Fissure excision increased the likelihood of an unhealed postoperative wound on day 30 (OR 18.7 95% CI: 5.8–60.4; p < 0.0001) and on day 45 (OR 5.23 95% CI: 1.97–13.8; p = 0.0008). In the main group, post-defecation pain intensity was significantly lower than in the control group during the first 30 days (p < 0.0001). On the 30th postoperative day, gas incontinence was reported by 9/50 (18.0%) patients in the main group and 17/50 (34%) in the control group (p = 0.1), while on the 60th day, 2/50 (4.0%) patients in the LIS group and 3/50 (6%) in the LIS + FE group (p = 1.0) reported gas incontinence. The median Wexner score on the 30th postoperative day was 1 (1; 1) in the LIS group and 2 (1; 3) in the LIS + FE group (p = 0.03). Univariate analysis showed that factors increasing the likelihood of anal incontinence on the 30th postoperative day were age (OR = 1.03; 95% CI: 1.0–1.07) and childbirth history (OR = 12.3; 95% CI: 1.3–118.3). Fissure excision had a greater negative impact on patients' quality of life in the early postoperative period. The median Hemo-Fiss score on the 30th postoperative day was 5.5 (0; 13) points in the main group and 11 (5; 20) points in the control group (p = 0.02). The median time of temporary disability was 9 (6; 11) days in the LIS group and 15.5 (12; 23) days in the LIS + FE group (p = 0.0006). In the long-term postoperative period (up to 1 year), the groups were fully comparable in complication rates and nature. Recurrence occurred in 1/44 (2.2%) patients in the main group and 2/43 (4.6%) patients in the control group (p = 1.0). A rectal fistula was identified in 2/44 (4.5%) patients in the main group and 1/43 (2.6%) in the control group. ASI was observed only in the control group in 1/43 (2.3%) patients. Profilometry measurements showed that maximum resting anal canal pressure was 102 (89; 111) mmHg in the main group and 96 (85; 112) mmHg in the control group (p = 0.08). The mean resting anal canal pressure was 55 (52; 59) mmHg in the LIS group and 52 (42; 58) mmHg in the LIS + FE group (p = 0.1). CONCLUSION: performing LIS without fissure excision prevents long-healing wound in the anal canal, reduces pain intensity, decreases the severity of anal incontinence, improves quality of life, and shortens temporary disability. Avoiding fissure excision does not lead to worsening of late outcomes.