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

BACKGROUND: Anal fistula commonly appears after incision and drainage of perianal abscess. Theoretically, fistula develops as a consequence of infection process. Antibiotic treatment was suggested to decrease the possibility of fistula development. OBJECTIVE: We hypothesized that antibiotic treatment has no influence on development of anal fistula after surgical treatment of perianal abscess. DESIGN: A single blind randomized prospective study. SETTING AND PATIENTS: Patients with primary cryptogenic abscess were eligible to participate. Patients were divided in two groups. Patients in Group I received amoxicillin 875mg/clavulanic acid 125mg during 7 days after surgery and Group II patients received no antibiotics. Study database included demographics, clinical and laboratory data. MAIN OUTCOME MEASURES: Patients were examined in our outpatient clinic 2 weeks, four months and 1 year after surgery and telephone questionnaire performed 6 month after surgery. Primary Outcome was formation of anal fistula. Secondary Outcome was recurrent perianal abscess. RESULTS: Overall 98 patients completed the study. Groups were not different on inclusion. Anal fistula was diagnosed in 16 (16.3%) patients in Group I (treatment group) and 10 (10.2%) patients in the 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: Relatively small number of patients treated in single Medical Center. CONCLUSION: Antibiotic therapy has no influence on anal fistula or recurrent perianal abscess formation after incision and drainage of perianal abscess. See Video Abstract .