Long-term outcomes after anal fistula surgery: results from two university hospitals in Thailand

Abstract

Purpose: This study aimed to evaluate long-term outcomes after anal fistula surgery from university hospitals in Thailand.

Methods: A prospectively collected database of patients with cryptoglandular anal fistula undergoing surgery from 2011 to 2017 in 2 university hospitals was reviewed. Outcomes were treatment failure (persistent or recurrent fistula), fecal continence status, and chronic postsurgical pain.

Results: This study included 247 patients; 178 (72.1%) with new anal fistula and 69 (27.9%) with recurrent fistula. One hundred twenty-one patients (49.0%) had complex fistula; 53 semi-horseshoe (21.5%), 41 high transsphincteric (16.6%), 24 horseshoe (9.7%), and 3 suprasphincteric (1.2%). Ligation of intersphincteric fistula tract (LIFT) was the most common operation performed (n=88, 35.6%) followed by fistulotomy (n=79, 32.0%). With a median follow-up of 23 months (interquartile range, 12-45 months), there were 18 persistent fistulas (7.3%) and 33 recurrent fistulae (13.4%)-accounting for 20.6% overall failure. All recurrence occurred within 24 months postoperatively. Complex fistula was the only significant predictor for recurrent fistula with a hazard ratio of 4.81 (95% confidence interval, 1.82-12.71). There was no significant difference in healing rates of complex fistulas among seton staged fistulotomy (85.0%), endorectal advancement flap (72.7%), and LIFT (65.9%) (P=0.239). Four patients (1.6%) experienced chronic postsurgical pain. Seventeen patients (6.9%) reported worse fecal continence.

Conclusion: Overall failure for anal fistula surgery was 20.6%. Complex fistula was the only predictor for recurrent fistula. At least 2-year period of follow-up is suggested for detecting recurrent diseases and assessing patient-reported outcomes such as chronic pain and continence status.

Keywords: Chronic pain; Outcomes; Rectal fistula; Surgery; Treatment failure.

Fig. 1.

Type of anal fistulas classified by their relationship to the anal sphincter complex. Intersphincteric fistula and low transsphincteric fistula were further grouped as ‘simple’ fistula (light blue background) whereas the others were grouped as ‘complex’ fistula (blue background).

Fig. 2.

Cumulative survivals without recurrent fistula. (A) All fistulas and (B) between the simple and complex type of anal fistula. HR, hazard ratio; CI, confidence interval.