The most extensive data regarding anesthetic and surgical risks for the gravida and her fetus are from the Swedish Birth and described by Mazze and Kallen (1989). The efects on pregnancy outcomes of 5405 nonobstetrical surgical procedures performed in 720,000 pregnant women from 1973 to 1981 were analyzed. For approximately half of these procedures, general anesthesia was used and commonly involved nitrous oxide supplemented by another inhalation agent or intravenous medications. These procedures were performed in 41 percent of women in the first trimester, 35 percent in the second, and 24 percent in the third. Overall, 25 percent were abdominal operations, and 20 percent were gynecological or urological procedures. Laparoscopy was the most frequently performed operation, and appendectomy was the most common second-trimester procedure.
Excessive perinatal morbidity associated with nonobstetrical surgery is attributable in many cases to the disease itself rather than to adverse efects of surgery and anesthesia. he Swedish Birth Registry again provides valuable data (Table Importantly, the incidences of congenital malformations or of stillbirths were not significantly diferent from those of nonexposed control newborns. However, incidences of low birthweight, preterm birth, and neonatal death in infants born to women who had undergone surgery were significantly greater.
TABLE 46-1. Birth Outcomes in 5405 Pregnant Women Undergoing Nonobstetrical Surgery
Major malformation 1.9% NS Stillbirth 7 per 1000 NS
Neonatal death by 7 days 10.5 per 1 000 <0.05
Preterm <37 wk 7.5% <0.05
Birthweight < 1500 g 1.2% <0.05 Birthweight <2500 g 6.6% <0.05 aCompared with 720,000 pregnancies in women without surgery.
NS = not significant. Data from Mazze, 1989.
Increased neonatal death rates were largely due to preterm birth. In two other studies, the preterm delivery rate in women undergoing nonobstetrical surgery was also elevated (Baldwin, 2015; Hong, 2006).
Rates of fetal abnormalities with maternal surgery in early pregnancy do not appear increased. Kallen and Mazze (1990) scrutinized 572 operations performed at 4 to 5 weeks' gestation and reported a nonsignificant relationship with elevated neural-tube defect rates. In a similar study from a Hungarian database, Czeizel and colleagues (1998) found no evidence that anesthetic agents were teratogenic.
Laparoscopy has become the most common first-trimester procedure used for diagnosis and management of several surgical disorders. In 2017, the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) updated its recommendations concerning laparoscopy use in pregnant women (Table 46-2).