Southwestern Surgical CongressWhen body mass index fails to measure up: perinephric and periumbilical fat as predictors of operative risk

•Alternative fat metrics to BMI are proposed: perinephric fat (PNF) and periumbilical fat (PUF).•In women, PUF and PNF were predictors of blood loss, and PNF of operative time.•PUF and PNF are quickly and reliably obtained from axial imaging.•PUF and PNF may offer improved metrics for risk stratification.

BackgroundObesity has been associated with worse outcomes and increased surgical technical difficulty. Perinephric fat (PNF) and periumbilical fat (PUF) are alternative metrics to body mass index. We hypothesized that PUF and PNF would offer improved prediction of perioperative risk.Methods249 patients were retrospectively reviewed after elective, pelvic colorectal resections. PNF and PUF were collected using axial imaging. Operative risk measurements included estimated blood loss (EBL) and operative time (OT).ResultsIn multivariate analyses of women, PUF and PNF were significant predictors of EBL; PNF was a significant predictor of OT. A 4.7-mm increase in PNF predicted a 15-minute increase in OT and 55-cc increase in EBL. An 8.6-mm increase in PUF predicted a 55-cc increase in EBL. In men, no metric was predictive.ConclusionsIn women, PNF and PUF may offer improved metrics for risk stratification, which can have important clinical and financial implications.