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

Abstract

(Anesth Analg. 2015;121:752–758) Bedside ultrasonography can be used to establish the gastric contents of pregnant women about to undergo general anesthesia for elective cesarean delivery. This could help avoid the serious complication of pulmonary aspiration by prompting anesthesiologists to discourage general anesthesia in a woman found to have a full stomach. In the past ultrasonography was not able to detect an empty stomach, but technological improvements have made this a possibility. This study investigated the qualitative and quantitative sonographic patterns of the gastric antrum in fasted pregnant patients.

Gastric Ultrasound for the Regional Anesthesiologist and Pain Specialist

“…[11][12][13][17][18][19] The questions that follow are: (a) How much gastric fluid is normal for a fasted individual? (b) Can US discriminate between a normal volume of baseline gastric secretions and a greater-than-normal volume consistent with a "full stomach?…”

“…These values are remarkably similar in obstetric and nonobstetric adult patients, as well as in pediatric and obese populations. [11][12][13][20][21][22][23][24] It seems reasonable therefore to use a threshold of 1.5 mL/kg to discriminate between fasting and greater than fasting gastric volumes. [15][16][17]23 Several authors have studied the mathematical correlation between the gastric antral cross-sectional area (CSA) and the total gastric fluid volume, 13,18,23,[25][26][27][28][29][30][31][32][33][34] with the majority reporting a linear correlation.…”

“…17,23 A grade 0 antrum (which appears empty in both positions) highly correlates with an empty stomach and is found in approximately half of all fasted subjects. [11][12][13]23 A grade 1 antrum (which appears empty in the supine position but where clear fluids become visible in the RLD) correlates with a volume of less than 100 mL in most cases and is also a common finding in healthy fasting individuals (approximately half of all cases). On the other hand, a grade 2 antrum (when clear fluid is evidenced in both examination positions) more often corresponds to a volume greater than 100 mL in adults and is not commonly seen in fasting individuals (<5%).…”

“…On the other hand, a grade 2 antrum (when clear fluid is evidenced in both examination positions) more often corresponds to a volume greater than 100 mL in adults and is not commonly seen in fasting individuals (<5%). 8,[11][12][13]17,19 Finally, a combination of qualitative US and volume assessment (if required) is used to interpret the gastric US findings in a binary manner as "empty stomach" (no content or low volume of clear fluid compatible with baseline secretions) or "full stomach" (solid content or a high volume of clear fluid inconsistent with baseline gastric secretions) (Fig. 8).…”

Through a glass darkly - ultrasound imaging in obstetric anaesthesia

“…Pregnant women are at increased risk of aspiration owing to a number of factors, including delayed gastric emptying. Ultrasonographic measurement of antral cross-sectional area is a validated method of gastric content assessment, and has been studied in women during labour [33] and before elective caesarean section [34]. In a study of labouring women at term, gastric ultrasound was performed when the anaesthetist was called to site an epidural and when the woman was diagnosed at full cervical dilation.…”