"Core out" or "curettage" in rectal advancement flap for cryptoglandular anal fistula.

Aim: Transanal advancement flap is a recognized technique for complex fistula. Management of the tract is open to discussion. Excision of the tract by the "core out" technique is difficult and could increase the risk of sphincter damage. Curettage is easier but it could increase the risk of recurrence. The aim of the present study was to assess the effect of both techniques on sphincter function and to study the clinical results.

Method: This is a retrospective analysis from a prospective database. One hundred nineteen consecutive patients with high cryptoglandular anal fistula were included. "Core out" technique was performed in 78 patients (group I) and "curettage" in 41 (group II). In both, a full-thickness rectal flap was advanced over the closed internal defect. Anorectal manometry was performed to assess sphincter function. Continence was assessed using the Wexner Scale. Recurrence was defined as the presence of an abscess or fistulization.

Results: Manometric results showed a significant decrease in the maximum resting pressure after surgery in both groups. The maximum squeeze pressure was significantly reduced only in group I (p < 0.001). No significant changes in Wexner score were observed. The overall recurrence rate was 5.88%, five of group I (6.4%) and two of group II (4.9%), without statistical significance (p = 0.74).

Conclusions: The core-out technique causes a significant decrease in squeeze pressures, which reflects damage to the external anal sphincter. This could lead to incontinence in high-risk patients. Curettage is a simple technique that preserves the values of squeeze pressures without increasing recurrence rates.