To evaluate the impact of lateral internal sphincterotomy on symptom resolution and changes in both overall and fecal incontinence–related quality of life in patients with chronic anal fissure, through pre- and postoperative assessment using EQ-5D-5L and FIQLS scales, and to identify clinical factors associated with early postoperative pain resolution.

An analytical before-and-after observational study was conducted using medical records of adult patients with chronic anal fissure who underwent lateral internal sphincterotomy between 2020 and 2024. Patients without postoperative follow-up or managed conservatively were excluded. The primary outcome was the change in quality of life, measured using the EQ-5D-5L scale (1). For patients with fecal incontinence, the FIQLS scale was also applied (2). A minimum sample size of 328 patients was estimated (effect size d = 0.2; alpha = 0.05; power = 95%). EQ-5D-5L analysis included the Paretian Classification, superiority probability, and Health Profile Grid. Statistical analysis was performed in RStudio, including Wilcoxon test for paired data, bivariate comparisons, and multivariable logistic regression with backward selection to identify factors associated with early postoperative pain resolution (within four days). Significance was set at p < 0.05.

332 patients with chronic anal fissure were analyzed; 52.1% were male (173/332), with a median age of 43 years (IQR 34–55). 77.7% (258/332) had a posterior anal fissure. The EQ-5D-5L scale showed improvement across all evaluated dimensions. According to the Paretian Classification of Health Change, 85.6% (279/326) of patients experienced overall health improvement. The greatest improvement was observed in the pain/discomfort dimension (96.9%; 281/290), followed by usual activities (59.6%; 109/183). These findings were supported by the analysis of probability of superiority (Mobility = 0.53, Self-Care = 0.54, Usual-Activities = 0.64, Pain/Disconfort = 0.92, Anxiety/Depression = 0.58) and visualized in the Health Profile Grid. In the analysis of probability of superiority in patients with preoperative incontinence, no changes in self-care and usual activities were observed (Table 1). Preoperative fecal incontinence was reported in 7.8% (26/332). Non statistically significant changes were observed in incontinence-related quality of life, as measured by the FIQLS (Table 2). A total of 13.2% of patients (44/332) experienced postoperative complications, including de novo fecal incontinence in 3.8% (16/332), with a mild to moderate impact as measured by the FIQLS (Table 2). At 120-day follow-up, 87.5% (14/16) reported resolution, while 12.5% (2/16) remained under treatment.
In the logistic regression, intraoperative ketorolac use was significantly associated with faster pain resolution (OR 22.54; 95%CI 9.5–60.5; p < 0.001). Preoperative mild pain (OR 0.22; 95%CI 0.032–0.86; p = 0.017) and concurrent fistulotomy (OR 0.24; 95%CI 0.064–0.71; p = 0.057) were linked to delayed pain resolution.

The assessment of quality of life using the EQ-5D-5L scale demonstrated a clear improvement in overall health status after lateral internal sphincterotomy for chronic anal fissure. Among patients with preoperative fecal incontinence, no worsening in quality-of-life impact was observed postoperatively. Despite concerns among colorectal surgeons regarding the potential risk of exacerbating incontinence, this analysis suggests that the procedure does not worsen fecal incontinence-related outcomes and is instead associated with symptom resolution and improved overall quality of life (3). Additionally, ketorolac use, performance of fistulotomy and preoperative pain severity may be significant predictors of faster postoperative recovery.

Lateral internal sphincterotomy proved effective in improving overall quality of life in patients with chronic anal fissure, particularly in reducing pain and discomfort. The procedure did not worsen fecal incontinence-related quality of life and was associated with symptom resolution. Intraoperative ketorolac use, preoperative pain level, and concurrent fistulotomy influenced early postoperative pain outcomes, supporting the procedure’s safety and clinical benefit.

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