Postoperative Infections in Non-Hysterectomy Endometriosis Surgeries: Association With the Vizient Vulnerability Index

INTRODUCTION: Endometriosis is a chronic, inflammatory condition associated with immune dysfunction and increased risk for surgical infection. We have previously demonstrated that a higher vulnerability index can correlate with worse surgical outcomes in gynecologic patients. While surgical morbidity in endometriosis has been broadly described, the specific risk of postoperative infections following minimally invasive, non-hysterectomy procedures remains uncertain. OBJECTIVE: To compare postoperative infection rates after minimally invasive, non-hysterectomy gynecologic procedures in patients with and without endometriosis, and to evaluate whether elevated vulnerability index scores further increase infection risk. METHODS: This was a retrospective cohort study using the Vizient Clinical Data Base, a national quality database that includes data from over 1,000 academic and community hospitals across the United States. We identified reproductive-aged women who underwent non-hysterectomy minimally invasive gynecologic surgery (MIS), including laparoscopic, robotic-assisted, and single-incision procedures, for benign indications. Patients were stratified based on the presence or absence of endometriosis. Surgical procedures were identified using Current Procedural Terminology (CPT) codes, and endometriosis diagnoses were confirmed using International Classification of Diseases, 9th and 10th Revisions (ICD-9 and ICD-10) codes. Hysterectomy cases were excluded due to existing recommendations for antibiotic prophylaxis in those procedures. The Vizient Vulnerability Index (VVI), a composite measure of social and health-related vulnerability, was used to assess population-level risk; where higher scores indicate greater social and health-related vulnerability. Categorical data were compared using chi-square test and logistic regression to estimate odds ratio (OR) [95% confidence interval (CI)]. RESULTS: The cohort comprised 2,366,068 patients; of these, 97,103 (4.10%) had a diagnosis of endometriosis, and 94,238 (3.98%) had pathology-confirmed endometriosis. The overall incidence of surgical site infection (SSI) within 30 days was 0.1% (n=1,876). Patients with a diagnosis of endometriosis experienced a higher rate of postoperative SSI compared to controls (0.44% vs 0.06%, P<0.001). Among those with pathology-confirmed endometriosis, the postoperative infection rate was 0.71%, compared with 0.05% in pathology-confirmed controls (P<0.001). All SSI subtypes were more common for patients with endometriosis (P<0.001). For pathology-confirmed cases versus controls, rates were higher for superficial SSI (0.59% vs 0.07%, P<0.001), deep SSI (0.57% vs 0.07%, P<0.001), organ-space infection (0.07% vs 0.01%, P<0.001), and urinary tract infection (0.9% vs 0.1%, P<0.001). The Vizient Vulnerability Index (VVI) was significantly associated with infectious morbidity. Compared with patients in the lowest quartile (Q1), those with pathology-confirmed endometriosis in higher quartiles demonstrated increased odds of SSI: Q2 OR 1.22 (95% CI 1.08–1.38), Q3 OR 1.31 (95% CI 1.15–1.48), and Q4 OR 1.23 (95% CI 1.08–1.40), with patients in the third quartile showing the highest risk. CONCLUSIONS: Following minimally invasive, non-hysterectomy surgery, patients with endometriosis experienced higher postoperative infection rates. This risk was further amplified among pathology-confirmed cases and those with higher vulnerability index scores. These findings highlight the importance of integrating biological and social determinants into perioperative planning and developing risk-stratified approaches to antibiotic prophylaxis.