Are Prophylactic Postoperative Antibiotics Preventing Sacral Neuromodulation Infections?

Objectives: Currently, there are no definitive guidelines for use of postoperative antibiotics after Sacral Neuromodulation (SNM). As a result, there is large practice pattern variation amongst providers. Our primary objective is to determine if additional antibiotics beyond preoperative intravenous (IV) antibiotics and surgical prep decrease postoperative infections. Our secondary objective is to evaluate if these additional antibiotics are associated with other postoperative complications.

Methods: This was a retrospective cohort study of all SNM procedures from January 2020 through January 2023 performed by 7 surgeons. All patients received preoperative IV antibiotics and a surgical prep. The primary outcome was a composite of postoperative infections (defined as cellulitis, abscess or infected implant) compared between patients who were given preoperative IV antibiotics alone or combined with postoperative antibiotics after either insertion of tined lead (stage 1) and/or after insertion of neurostimulator (stage 2). Secondary outcomes included other postoperative complications such as antibiotic side effects and hematoma. Student’s t-test was utilized for parametric continuous variables and Chi-square test was utilized for categorical analysis (Stata Version 17).

Results: The cohort consisted of 127 patients who underwent SNM, of which 57 (44.9%) received only preoperative antibiotics and 70 (55.1%) received preoperative antibiotics and postoperative antibiotics. Of the patients who received postoperative antibiotics, 34 (48.6%) received cephalexin, 33 (47.1%) received sulfamethoxazole-trimethoprim, 3 (4.3%) received an alternative antibiotic. There were more diabetics in the postoperative antibiotic group (p < 0.01) (Table 1). Two patients (1.6%) experienced a postoperative infection. Although both postoperative infections occurred in patients that received postoperative antibiotics, this was not statistically significant [0% (n=0) vs 6.1% (n=2), p = 0.198] (Table 1). Of the two infections, 1 patient was diagnosed with cellulitis and 1 patient had an infected implant requiring explantation. Another two patients had complications from antibiotic use: 1 patient had antibiotic side effects and 1 patient had a rash secondary to surgical prep. Baseline characteristics were compared between patients with and without an infection and there was no significant association between variables including previous MRSA infection (p =0.63) and diabetes mellitus (p = 0.51) (Table 2).

Conclusions: Additional postoperative antibiotics did not decrease infection rates in patients undergoing SNM. All infections occurred in the group that received postoperative antibiotics; however, this analysis is limited by a small sample size. While there was no significant difference in infection rates, it does call into question the utility of postoperative antibiotics since additional antibiotic use raises other risks. Similar comparative analyses should be performed with larger sample sizes.