Qualitative Ultrasound Assessment of the Gastric Content of Pregnant Women at Term
Abstract Number: S-42
Abstract Type: Original Research
Background: Gastric aspiration is a constant preoccupation in obstetric anesthesia. Although gastric emptying of non-laboring pregnant women is known to be similar to that of non-pregnant women, it is delayed once labor starts. In addition, there are many urgent situations in obstetrics when the status of the gastric content is a concern. A bedside, non-invasive method of identifying the prandial status of a patient would be of great value in obstetrics. In the non-pregnant population, gastric ultrasound assessment focused on the gastric antrum has shown to be a feasible imaging tool to qualitatively assess the gastric content in the perioperative period (1). It is possible that this novel approach can also be extended to the obstetric population. The purpose of this study is to evaluate the feasibility of the qualitative ultrasound assessment of gastric content of non-laboring pregnant patients in the third trimester of pregnancy by anesthesiologists.
Methods: This is a randomized, blind, observational study. With REB approval and informed consent, pregnant women ≥ 30 weeks gestational age are randomized to have an ultrasound assessment of their stomach in a fasting state (> 8 hours), or after ingestion of fluid only, or solid food. Three anesthesiologists trained in gastric ultrasonography perform the assessment using an ultrasound unit with a low frequency curved array transducer (5-2 MHz). With the patient in a 45 degree semi-recumbent position, the assessment is done in the sagittal plane, covering the epigastric area in a fan-like manner, from the left towards the right subcostal area, aiming at the adequate visualization of the gastric antrum. Four ultrasonographic diagnostic categories are possible: empty, fluid, solid and inconclusive. The primary outcome is the inter-rater reliability of the ultrasonographic diagnosis of the gastric status among the three anesthesiologists, compared to the patient allocated gastric content group. The sample size will include 32 subjects. Analysis will include Kappa statistics and proportions of specific agreement.
Results: Data collection is ongoing and will be concluded for presentation at SOAP meeting. Typical sonograms of an empty and a full stomach are shown in the picture.
Discussion: In the hands of properly trained anesthesiologists, ultrasound may be a feasible tool to qualitatively evaluate the gastric content of non-laboring pregnant women.
References: Perlas A et al. Anesthesiology 2009;111:82-9