Extreme horseshoe and circumanal anal fistulas-challenges in diagnosis and management.

OBJECTIVES

Extreme horseshoe anal fistulas are rare, and there are little data on the diagnosis and management of these fistulas.

MATERIALS AND

METHODS

Patients with horseshoe anal fistula, in which the fistula tract encircled more than 75% of the anal circumference were included in the study. All patients were assessed by a preoperative magnetic resonance imaging (MRI). The patients were managed by a sphincter-sparing procedure. The continence was evaluated by an objective continence scoring system (Vaizey's scores).

RESULTS

1059 anal fistula patients were operated on over 7-years with a median follow-up of 36 months (range: 5-79 months). There were 47/1059 (4.4%) patients with extreme horseshoe anal fistulas. In 4/47 patients, the fistulas were complete circumanal (encircling anal canal completely). The mean age was 39.5 ± 10.9 years, M/F-41/6. The fistula was supralevator in 12/47 (25.5%), had an associated abscess in 28/47 (59.6%), and was recurrent in 33/47 (70.2%) patients. The tracts were intersphincteric in 27/47, transsphincteric in 2/47, and both (intersphincteric and transsphincteric) in 18/47 patients. All patients (n = 47) were managed by a sphincter-sparing procedure. Four patients were lost to follow-up. The fistula healed completely in 34/43 (79%) patients. There was no significant difference between preoperative and postoperative Vaizey's continence scores 0.031 ± 0.17 and 0.033 ± 0.18 respectively (P=0.90, Mann-Whitney U-test).

CONCLUSION

Extreme horseshoe fistulas are rare, with an incidence of about 4% (in a referral practice). The missed diagnosis of circumferential tracts could lead to a recurrence. MRI was pivotal to confirm the diagnosis. Proper identification and management of internal opening and adequate drainage of all tracts were crucial for successfully treating extreme horseshoe fistulas.