Term pregnant patients have similar gastric volume to non-pregnant females: a single-centre cohort study.

BACKGROUND

The physiological changes of pregnancy can increase the risk of peri-partum pulmonary aspiration. There is limited objective information regarding gastric volumes in pregnant patients. The aim of this cohort study was to characterise prospectively the range of gastric-fluid volume in term non-labouring pregnant patients compared with a historical cohort of non-pregnant females.

METHODS

Fasted non-labouring term pregnant patients scheduled for elective Caesarean delivery underwent a standardised gastric ultrasound examination. Gastric content was evaluated qualitatively (type of content), semi-quantitatively (Perlas grades), and quantitatively (volume). The antral cross-sectional area and volume were compared with those of a retrospective cohort of non-pregnant females from the same institution. Descriptive statistics were used to describe the central tendency through mean and median values. Dispersion was evaluated with standard deviation and inter-quartile range, and the higher end of the distribution as 95th percentile.

RESULTS

Non-labouring pregnant (59) and non-pregnant (81) subjects were studied. The range of estimated total gastric-fluid volume (P=0.96) and volume per body weight (P=0.78) was not significantly different between cohorts. An estimated volume of 115 ml (102-143) vs 136 ml (106-149) and volume per body weight of 1.4 ml kg (1.2-2.8) vs 2.0 ml kg (1.5-2.7) corresponded to the 95th percentile (95% confidence interval) values in the pregnant and non-pregnant cohort, respectively.

CONCLUSIONS

Baseline gastric volume of non-labouring pregnant patients at term is not significantly different from that of non-pregnant females. This information will be helpful to interpreting findings of gastric point-of-care ultrasound in obstetric patients.