According to Miller, “Progesterone relaxes smooth muscle; consequently, it impairs esophageal and intestinal motility during pregnancy. Whether gastric emptying is delayed during pregnancy is controversial. Wong and coworkers suggest that the ingestion of 300 mL of water may actually enhance gastric emptying in healthy, term, nonobese, nonlaboring parturients. However, the risk of pulmonary aspiration of gastric contents remains real in parturients”
That said, deaths from aspiration occur as commonly as deaths from cannot intubate / cannot ventilate situations. Note that Hawkins’ analysis of maternal deaths found 33 deaths from aspiration during general anesthesia, as compared to 37 deaths from either “induction/intubation problems” or “inadequate ventilation” [Hawkins JL et al. Anesthesiology 86: 277, 1997]. Note that these data are pre-LMA in the United States (1990 was the last year included in Hawkins’ analysis, the LMA was not available until 1991). Stoelting recommends treating all pregnant women as though they had a full stomach (RSI?), using a cuffed endotracheal tube, and administering non-particulate antacids prior to induction.
GI Effects of Pregnancy
- Relaxation of smooth muscle
- Impaired esophageal and intestinal motility
- Effect on gastric emptying is controversial