Routine operative swab cultures and post-operative antibiotic use for uncomplicated perianal abscesses are unnecessary.

BACKGROUND: Routine swab cultures for perianal abscesses remain commonplace in surgical practice. However, patients are often discharged post-operatively prior to the culture results being made available. Consequently, intra-operative swab cultures rarely impact subsequent management and outcomes. Similarly, the use of broad-spectrum antibiotics for perianal abscesses post-drainage also remains prevalent, albeit with questionable benefit.
METHODS: The records of all patients diagnosed with perianal abscess from January 2011 to December 2011 were reviewed. Patients with complicated perianal abscesses or recurrent abscesses previously treated before the study period were excluded. The demographics, medical co-morbidities, intra-operative findings, swab cultures, microbiological results and use of post-operative antibiotics were reviewed. Subsequent wound healing and follow-up were also recorded.
RESULTS: Two hundred and seven patients were admitted to our institution for perianal abscesses in 2011. After excluding 35, the remaining 172 patients were analysed. One hundred and thirty-four patients (78%) had swab cultures performed intra-operatively but 80% of these were discharged prior to the culture results being available. One hundred and eight (63%) were discharged with outpatient antibiotics. During the index admission and subsequent follow-up, swab culture results were not documented to be reviewed by the attending physician 96.5% of the time. Sixteen patients required repeat surgery for recurrence of anorectal sepsis. We found that the use of antibiotics after the index surgery did not confer a statistically significant benefit.
CONCLUSION: Routine swab cultures are unnecessary and do not affect management and outcome. The use of post-operative antibiotics may reduce the rates of recurrence, but this benefit was not found to be statistically significant.