Comparison of operating field sterility in open versus minimally invasive microdiscectomies of the lumbar spine.

Background: Postoperative wound infection is a preventable risk that can lead to significant adverse outcomes and increased cost of care. Minimally invasive surgeries (MIS) have been found to have lower rates of postoperative infection compared with the traditional approach. To assess if the reported difference is related to intraoperative contamination or to other factors, we assessed the surgical field for sterility.

Methods: We compared 10 MIS versus 10 traditional microdiscectomies. Swabs of the operating field were obtained before and after the procedure from multiple sites in the operating room. Positive and negative controls were taken of the skin immediately before and after preparation of the incision site. All swabs were plated out on Columbia blood agar plates and grown for 48 hours. Colony counting was performed to determine growth.

Results: There was no statistically significant difference in the colony counts of swab sites in traditional microdiscectomies compared with MIS microdiscectomies. There was no significant contamination of the operating field using either approach.

Conclusions: In this prospective study, we found that there was no significant difference in bacterial counts in swabs of operative sites in either traditional or MIS microdiscectomies, suggesting that the decreased rate of postoperative infection in the reported literature for MIS cases may be related to other factors, such as patient selection and/or postoperative care.