ESSENTIALS OF DIAGNOSIS
Aspiration of gastric contents can occur during pregnancy, most commonly during labor or after delivery, and particularly, during induction of general anesthesia.
Aspiration can lead to pneumonitis that may be life-threatening.
The first large series of patients with pregnancy-related aspiration pneumonitis was published by Mendelson in 1946. He reported this complication resulting from inhalation of gastric contents in women undergoing obstetric anesthesia. These observations have long influenced the management of labor and delivery, despite an increasing number of publications calling for a reassessment of their validity at the present time.
A number of factors in pregnancy contribute to a higher risk of aspiration of gastric contents and aspiration pneumonitis. The increased risk during pregnancy is due to elevated intra-abdominal pressure, decreased gastroesophageal sphincter tone, diminished laryngeal reflexes, and delayed gastric emptying. Aspiration may be the result of passive regurgitation or active vomiting. Aspiration was reported to account for 30–50% of maternal deaths related to anesthetic complications, and if bacterial infection after aspiration occurs, usually after 24–72 hours, the mortality rate can be even higher. Due to increased use of neuraxial anesthesia as well as advances in obstetric anesthetic management, the incidence of aspiration pneumonitis and its complications has been greatly reduced. Nevertheless, the increased rate of cesarean sections, over 20% in many developed countries, makes aspiration of gastric contents an important contributor to maternal morbidity and mortality, since general anesthesia is still widely used when neuraxial anesthesia is contraindicated or has been unsuccessful. The highest risk of aspiration is reported in relation to emergency cesarean sections.
Because of the high risk associated with aspiration pneumonitis, including the possibility of maternal death, every effort should be made to prevent this potentially catastrophic condition. General anesthesia is the main risk factor related to aspiration, and expert airway management during induction and intubation is extremely important.
There are widely varying practice recommendations throughout the world in regard to oral intake during labor. It is still a controversial subject particularly because of some reports challenging the notion that pregnancy and labor impair gastric motility and stomach emptying. To date, there is insufficient published evidence to draw definitive conclusions. In the United States, guidelines from both the American Society of Anesthesiology (ASA) and the American Society of Obstetricians and Gynecologists (ACOG) allow clear liquids during labor but not intake of solid food during active labor because of the inability to predict who will need general anesthesia for a cesarean section. Women undergoing elective cesarean delivery should fast for 6–8 hours, depending on the type of food ingested. At present, obstetric patients are considered at increased risk for pulmonary aspiration when undergoing surgery under general anesthesia and are recommended to have pharmacologic prophylaxis to neutralize gastric acidity and to reduce gastric content volume, as well as to undergo rapid sequence induction of ...