Mucosal advancement flap for fistula-in-ano: A single-institution experience

Background and Objective: Mucosal advancement flap (MAF) is a well-described definitive treatment for complex fistula-in-ano, with high healing rates ranging from 37 to 87% for cryptoglandular fistula, but with mild incontinence rates of up to 35%. There is a paucity of Australian data to support the efficacy and complication rates of MAF, nor predictive factors for success. Patients and Methods: This was a retrospective study, with ethical approval granted by St. Vincent's Hospital Melbourne (SVHM) Quality and Risk Unit. Patients who underwent MAF at SVHM and St Vincent's Private Hospital Fitzroy from 2011 to 2015 were included in the study; all data were collected from patient medical records. Results: A total of 65 patients were treated with MAF during the study period. Fistula etiology was cryptoglandular in 82%, anovaginal in 11%, and perianal Crohn's disease in 7% of patients. Overall success rates for MAF were 66% for cryptoglandular fistula, 14% for anovaginal fistula, and 40% for Crohn's fistula. Excluding anovaginal fistulae, the success rate of MAF was 74% for males and 57% for females. MAF performed for an anterior internal opening was associated with a success rate of 65% versus 56% for a posterior internal opening. Postoperative fecal incontinence rate was 6%. Five of the patients with failed MAF underwent a second sphincter-preserving procedure; none of these were successful. Conclusion: This study supports the use of MAF for the treatment of complex fistula-in-ano, with a success rate compatible with existing literature and a low incontinence rate.