Ultrasound your NPO: Effect of body mass index on gastric volume in term pregnant women - Retrospective case series.

Introduction: A common belief has been that obese patients are prone to develop aspiration of gastric contents when general anesthesia is administered. We aimed to determine the correlation between antral cross-sectional area as a surrogate of gastric volume measured by gastric ultrasound, and body mass index (BMI) in term pregnant women scheduled for elective cesarean section.

Methods: A cross-sectional observational study was conducted on forty-two term pregnant patients scheduled for cesarean section. A preoperative qualitative and quantitative ultrasound assessment of the antral area was performed on the day of surgery. Gastric volume as a function of BMI was evaluated.

Results: A significant correlation was found between BMI and gastric antral area (p = 0.001), as well as with longitudinal diameter (p < 0.001). This correlation is independent of gravidity and parity.

Conclusion: BMI is an independent predictor of antral cross sectional area and gastric volume in term pregnant patients scheduled for cesarean section. Perioperative fasting guidelines in pregnancy should be adjusted in obese and morbidly obese pregnant women.