Patterns and Outcomes of Treatment Failure after Ligation of Intersphincteric Fistula Tract for Cryptoglandular Anal Fistula: Analysis of 200 Failed Ligation of the Intersphincteric Fistula Tract Cases

BACKGROUND: Despite generally favorable outcomes of ligation of intersphincteric fistula tract for anal fistula, several patients experience persistent or recurrent disease. OBJECTIVE: This study aimed to identify patterns of treatment failure after ligation of intersphincteric fistula tract and evaluate their outcomes. DESIGN: Multicenter retrospective study. SETTING: Five university hospitals in Thailand. PATIENTS: Those diagnosed with persistent or recurrent cryptoglandular anal fistula after ligation of intersphincteric fistula tract between 2012 and 2020. MAIN OUTCOME MEASURES: Fistula characteristics, patterns of treatment failure and outcomes of subsequent management were analyzed. RESULTS: A total of 200 patients were included, of whom 12.5% had persistent fistulas and 87.5% had recurrence. Median time to recurrence was 6 months (range, 1-48). Most treatment failures (n = 186, 93%) occurred within one year after surgery. Six distinct patterns of treatment failure were identified. The most common was type 1 (I–E, tract running from the previous internal opening (I) to an external opening (E) - known as an original fistula: n=116, 58%), followed by type 2 (I–L, tract running from the previous internal opening (I) to an unhealed intersphincteric wound - known as an intersphincteric fistula: n = 56, 28%). Type 1 failure was effectively treated by redo- ligation of intersphincteric fistula tract with an 87% success rate. Overall, the healing rate was 90.5% - with a median follow-up period of 18 months (range, 12-38). LIMITATIONS: Exclusion of non-cryptoglandular fistulas may limit generalizability. The retrospective multicenter design and surgeon-dependent decision-making may have introduced selection bias and heterogeneity in surgical technique. CONCLUSIONS: Most treatment failures occurred within one year after ligation of intersphincteric fistula tract. Understanding the six distinct failure patterns enables more appropriate surgical decision-making. The majority represented either recurrence of the original tract or persistence within the intersphincteric space. See Video Abstract .