Determinants of surgical site infection after breast biopsy

BACKGROUND: Surgical site infections (SSI) following clean and clean-contaminated ambulatory surgery at Bon Secours Cottage Health Services are monitored utilizing a postdischarge surveillance form in addition to traditional surveillance. From January 2000 to December 2002, the clean procedure SSI rate was 0.73% (31/4266) versus 1.58% (15/950) for breast biopsy, P = .04. A case-control study was performed to identify risk factors for infection. METHODS: A case patient was identified as any patient having an ambulatory breast biopsy from January 2000 to December 2002 with SSI identified by the Centers for Disease Control and Prevention (CDC) definition of nosocomial infection. For each case patient, 3 randomly selected control patients were matched by date and procedure. RESULTS: Factors significantly associated with the development of SSI were duration of surgery (case mean, 71.7 minutes vs control mean, 34.7 minutes, P < .01) and presence of surgical drains (26.7% of cases vs 6.7% of controls, P = .04). Factors determined not to be associated with SSI were obesity (P = .88) and preoperative needle localization (P = .88). CONCLUSIONS: We conclude that there is a significant difference between the breast biopsy infection rate and the clean procedure infection rate in ambulatory surgery. Duration of surgery and presence of surgical drains were associated with increased infection rate.