Proposal for a new classification of anorectal abscesses based on clinical characteristics and postoperative...

Current surgical procedures for anorectal abscesses, including incision and drainage alone or combined concurrent fistulotomy, remain controversial primarily due to the unpredictability of postoperative recurrence or the progression to anal fistula.

To evaluate factors that predict postoperative recurrence of anorectal abscesses and propose a new classification to guide surgical procedures.

In this retrospective study, 525 patients with anorectal abscesses treated by incision and drainage alone, at a tertiary general hospital from August 2012 to July 2022, were included. A new classification for anorectal abscesses based on their propensity to develop into fistulas, considering 18 other potential risk factors, was established. These factors, from electronic medical records, were screened for significance using the χ² test and subsequently analyzed with multivariate logistic regression to evaluate their relationship with postoperative recurrence of anorectal abscesses.

One year post-follow-up, the overall recurrence rate was 39%:81.0% and 23.5% for fistula-prone and non-fistula-prone abscesses, respectively. Univariate χ² analysis showed significant differences in recurrence rates based on anatomical classifications and pus culture results (P < 0.05). Fistula-prone abscess, ≥ 7 days between symptom onset and surgery, chronic diarrhea, preoperative antibiotic use, and local anesthesia were risk factors for recurrence, while diabetes mellitus was protective (P < 0.05). Moreover, fistula-prone abscess [odds ratio (OR) = 7.651, 95%CI: 4.049-14.458, P < 0.001], ≥ 7 days from symptom onset to surgery (OR = 2.137, 95%CI: 1.090-4.190, P = 0.027), chronic diarrhea (OR = 2.508, 95%CI: 1.216-5.173, P = 0.013), and local anesthesia (OR = 2.308, 95%CI: 1.313-4.059, P = 0.004) were independent risk factors for postoperative anorectal abscess recurrence using multivariate logistic regression. Body mass index ≥ 28 (OR = 2.935, 95%CI: 1.203-7.165, P = 0.018) was an independent risk factor for postoperative recurrence of non-fistula-prone abscess.

The choice of surgical procedure for treating anorectal abscesses should follow this new classification. Prompt and thorough incision and drainage can significantly reduce postoperative recurrence.