General anesthesia for maternal surgery during pregnancy: dogmas, myths and evidence, a narrative review

Up to 1% of pregnant women require general anesthesia and maternal non-obstetric surgery during pregnancy, of which urgent abdominal procedures are most commonly indicated. This narrative review summarizes several dogmas and myths on the management of general anesthesia during pregnancy and the corresponding evidence. While historical studies found delayed gastric emptying during pregnancy, recent evidence concluded that gastric emptying remains nearly normal during the entire pregnancy until the onset of labor. To correctly estimate the aspiration risk, gastric ultrasound should be increasingly performed. Based on the available evidence, the application of cricoid pressure should be discouraged during rapid sequence induction of pregnant women. A cuffed endotracheal tube is traditionally recommended, but laryngeal masks have been used in > 9000 patients undergoing cesarean section without observation of aspiration. All material to manage a difficult airway should be available as difficult intubation remains an ongoing concern in obstetrics. Risk factors for difficult intubation are nonobstetric in nature. Due to the lack of evidence for hemodynamic management, it is not possible to make an evidence-based recommendation. We recommend to adhere to the expert opinion of maintaining maternal blood pressure close to the normal physiologic value by using (15°-)30° left lateral tilt position, intravenous fluids and noradrenaline or phenylephrine. Most recent clinical observational studies suggested to consider laparoscopic over open surgery as a standard treatment for abdominal surgery. While animal studies observed impaired fetal brain development after prenatal anesthesia exposure, this could not be confirmed by an observational clinical study.