Antibiotic administration outside of 2 hours prior to skin incision increases deep surgical site infection rates in complicated appendicitis

Background: Surgical Care Improvement Project guidelines recommend antibiotic administration prior to incision for patients undergoing many elective surgical procedures to reduce the risk of surgical site infections (SSI). However, guidelines exclude patients with active infections and it is unknown whether this practice reduces SSI in pediatric patients undergoing appendectomy for acute appendicitis. The purpose of our study was to determine whether prophylactic antibiotic administration within 2 hours prior to incision affects infectious complication rates in these patients.

Methods: This is a retrospective review of pediatric patients who underwent appendectomy for appendicitis at our institution from 2016-2018. Patients were stratified by uncomplicated or complicated appendicitis. Rates of post-operative complications, including superficial SSI, deep SSI, bowel obstruction, C. difficile infection, ICU admission, and hospital readmission, were calculated. Fisher's exact test was used to compare these outcomes between patients who received antibiotics within 2 hours of skin incision (“within2hrs”) and patients whose last dose of antibiotics was outside of 2 hours prior to skin incision ("outside2hrs").

Results: 465 patients were included in this study; 364 patients (78.3%) had uncomplicated appendicitis. None of these patients developed deep SSI and there was no difference in superficial SSI rates (2.3 vs 1.5%, p=1) between the “within2hrs” (n=299) and “outside2hrs” (n=65) groups. In patients with complicated appendicitis (n=101), there was also no difference in superficial SSI rates (1.4% vs 0%, p=1). However, there was a significantly higher rate of deep SSI in the “outside2hrs” group (60% vs 23.9%, p= 0.0011). There was no statistically significant difference between the “within2hrs” and “outside2hrs” groups for the other complications analyzed.

Conclusion: The timing of preoperative antibiotic administration did not change outcomes for patients with uncomplicated appendicitis. However, for patients with complicated appendicitis, receiving antibiotics greater than 2 hours prior to incision was associated with a significantly increased deep SSI rate.