Background: Fistulotomy plus primary sphincteroplasty for complex anal fistulas is regarded with scepticism, mainly because of the risk of postoperative incontinence.
Objectives: The aim of this study was to evaluate safety and effectiveness of this technique in medium-term follow up and to identify potential predictive factors of success and postoperative continence impairment.
Design and setting: This was a prospective observational study conducted at a tertiary care university hospital in Italy.
Patients: A total of 72 patients with complex anal fistula of cryptoglandular origin underwent fistulotomy and end-to-end primary sphincteroplasty; patients were followed up at 1 week, 1 and 3 months, 1 year, and were invited to participate in a recent follow-up session.
Main outcome measures: Success regarding healing of the fistula was assessed with 3-dimensional endoanal ultrasound and clinical evaluation. Continence status was evaluated using the Cleveland Clinic fecal incontinence score and by patient report of post-defecation soiling.
Results: Of the 72 patients, 12 (16.7%) had recurrent fistulas and 29 patients (40.3%) had undergone seton drainage before definitive surgery. At a mean follow-up of 29.4 (SD, 23.7; range, 6-91 months, the success rate of treatment was 95.8% (69 patients). Fistula recurrence was observed in 3 patients at a mean of 17.3 (SD, 10.3; range, 6-26) months of follow-up. Cleveland Clinic fecal incontinence score did not change significantly (p = 0.16). Eight patients (11.6% of those with no baseline incontinence) reported de novo postdefecation soiling. None of the investigated factors was a significant predictor of success. Patients with recurrent fistula after previous fistula surgery had a 5-fold increased probability of having impaired continence (relative risk = 5.00, 95% CI, 1.45-17.27, p = 0.02).
Limitations: The study was limited by potential single-institution bias, lack of anorectal manometry, and lack of quality of life assessment.
Conclusions: Fistulotomy with end-to-end primary sphincteroplasty can be considered to be an effective therapeutic option for the treatment of complex anal fistulas, with low morbidity, a high rate of success even at long-term follow-up, and a very low rate of postoperative major fecal incontinence, although minor impairment of continence (postdefecation soiling) may occur. Caution should be used in selecting patients with a history of recurrent fistula and fecal incontinence.