Evidence-based wound classification for vulvar surgery: Implications for risk adjustment

Objectives: The correct wound classification for vulvar procedures (VP) is ambiguous according to current definitions, and infection rates are poorly described. We aimed to analyze rates of surgical site infection (SSI) in women who underwent VP to correctly categorize wound classification. Methods: Patients who underwent VP for dysplasia or carcinoma were collected from the National Surgical Quality Improvement Program database (NSQIP). SSI rates of vulvar cases were compared to patients who underwent abdominal hysterectomy via laparotomy, stratified by the National Academy of Sciences wound classification. Descriptive analyses and trend tests of categorical variables were performed. Results: Between 2008 and 2016, 2116 and 31,506 patients underwent a VP or TAH, respectively. Among VP, 1345 (63.6%), 364 (17.2%), and 407 (19.2%) women underwent simple vulvectomy, radical vulvectomy, or radical vulvectomy with lymphadenectomy, respectively. The overall rate of SSI for VP was higher than that observed for TAH (5.6% vs. 3.8%; p < 0.0001). While patients undergoing TAH displayed a corresponding increase in the rate of SSI with wound type (type I: 3.4%; type II: 3.8%, type III: 6.8%; type IV 10.6%; p < 0.001), no such correlation was observed for simple VP (type I: 3.3%, type II: 3.0%; type III: 3.2%; type IV: 0%; p = 0.40). On the other hand, a non-significant correlation was observed for radical VP (type I: 4.0%, type II: 10.1%; type III: 14.3%; type IV: 20.0%; p = 0.08). The overall rate of SSI in patients undergoing any radical VP was similar to patients undergoing hysterectomy with a type IV wound (10.1% vs 10.6%, p = 0.87). Conclusion: Patients undergoing VP are at high risk of infection. Simple vulvectomy should be classified as a type II and radical vulvectomy as a type III wound. These recommendations are important for proper risk adjustment.