Long-term outcome following loose-seton technique for external sphincter preservation in complex anal fistula

Background: This study determined the long-term outcome after use of the loose-seton technique (LST) to eradicate complex fistula in ano. Methods: Twenty patients whose complex fistula in ano was treated by the LST a minimum of 10 years previously were assessed by case-note review, supplemented where necessary by mailed and telephone interview. Results: Eighteen patients had a trans-sphincteric and two a suprasphincteric fistula. There were seven supralevator and 12 ischiorectal secondary extensions. At short-term follow-up, a median of 6 months following seton removal, perianal sepsis had been eradicated in 13 of 20 patients. However, the long-term success rate of the LST was lower than that noted in the short term (four versus 13 of 20). Sixteen patients had persisting or recurrent sepsis, necessitating further surgery in 13. In the long term, external sphincter division was necessary to control sepsis in seven of the 20 patients compared with three of 20 patients at short-term follow-up. The rate of relapse in those with Crohn's disease and cryptoglandular fistula in ano was similar (five of six versus 11 of 14; P = 1.000). The fistula recurred in seven, 11 and 15 patients at 6, 15 and 60 months respectively after seton removal. Conclusion: The success rate of the LST for complex fistula in ano falls over time. Counselling before seton removal should emphasize that, although most patients do not require sphincter division and some are cured by this technique, many patients develop further sepsis that usually requires surgery.