Antibiotic Treatment Has No Influence on Anal Fistula Formation and Recurrent Perianal Abscess After Incision and Drainage of Cryptogenic Perianal Abscess: A Randomized Single-Blinded Prospective Study

BACKGROUND: Anal fistula commonly appears after incision and drainage of a perianal abscess. Theoretically, a fistula develops as a consequence of the infection process. Antibiotic treatment was suggested to decrease the possibility of fistula development. OBJECTIVE: We hypothesized that antibiotic treatment has no influence on the development of anal fistula after surgical treatment of perianal abscess. DESIGN: A single-blinded randomized prospective study. SETTINGS: Patients with primary cryptogenic abscesses were eligible to participate. PATIENTS: Patients were divided into 2 groups. Patients in group I received amoxicillin 875 mg/clavulanic acid 125 mg during 7 days after surgery, and patients in group II received no antibiotics. The study database included demographics and clinical and laboratory data. MAIN OUTCOME MEASURES: Patients were examined in our outpatient clinic 2 weeks, 4 months, and 1 year after surgery, and a telephone questionnaire was performed 6 months after surgery. The primary outcome was the formation of anal fistula. The secondary outcome was recurrent perianal abscess. RESULTS: Overall, 98 patients completed the study. Groups were not different in inclusion. Anal fistula was diagnosed in 16 patients (16.3%) in group I (treatment group) and 10 patients (10.2%) in group II (control group; p = 0.67). Nine patients (9.2%) developed recurrent perianal abscess, 4 in the treatment group and 5 in the control group (p = 0.73). LIMITATIONS: A relatively small number of patients were treated in a single medical center. CONCLUSION: Antibiotic therapy has no influence on anal fistula or recurrent perianal abscess formation after incision and drainage of perianal abscess.