Bedside Gastric Ultrasonography in Term Pregnant Women Before Elective Cesarean Delivery: A Prospective Cohort Study.

BACKGROUND: Bedside gastric ultrasound can reliably assess gastric contents in the perioperative period. We aimed to describe the qualitative and quantitative ultrasound assessment of the gastric antrum in fasted pregnant women at term.

METHODS: Pregnant women were examined after a minimum period of overnight fasting (solid food, 6 hours; clear liquids, 2 hours) before their scheduled cesarean delivery. A standardized ultrasound examination of the gastric antrum was performed. Based on the qualitative assessment in the supine and right lateral decubitus positions, women were classified using a 3-point grading system (grade 0, no fluid; grade 1, fluid seen in right lateral decubitus position only; and grade 2, fluid seen in the both supine and right lateral decubitus positions). A quantitative assessment of the antral cross-sectional area (CSA) was performed using still images in the right lateral decubitus position.

RESULTS: One hundred three women were included in the study; 53 of 103 exhibited grade 0 and 49 of 103 exhibited grade 1 antrum. One woman presented a grade 2 antrum (1/103 = 0.97%; 95% confidence interval [CI], 0.05%-6.06%). Overall, 95% of fasting subjects presented with an antral CSA ≤9.6 cm (95% CI, 8.6-10.3 cm) in the right lateral decubitus position (median [interquartile range] = 4.5 [3.2] cm), corresponding to an estimated gastric volume of ≤117 mL (95% CI, 108-127 mL) or ≤1.5 mL/kg (95% CI, 1.3-1.7 mL/kg).

CONCLUSIONS: All women but one presented with antral CSA compatible with residual gastric fluid. The qualitative 3-point grading system may be used to assess individual risk of perioperative gastric content aspiration. Our results suggest that an antral CSA of 10.3 cm in the right lateral decubitus position more accurately describes the upper limit of normal findings in the fasted pregnant patient at term.