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Anesthesia for Surgery in Pregnant Patients

By Laura E Gilbertson, M.D., Milad Sharifpour, M.D., and Grant C Lynde, M.D.

More than 75,000 pregnant patients undergo non-obstetric surgery in the United States each year. Fortunately, good preparation and planning can lead to good outcomes for both mother and child.

Finding physicians and hospitals with experience in caring for parturients with comorbid conditions is one of the most important considerations. Secondarily, attempting to schedule the surgery for the second trimester –when most organogenesis has been completed, but before the risk of preterm delivery increases –is the second-most important consideration.

It’s important for all physicians referring pregnant patients for surgery to be able to accurately educate their patients on the anesthetic considerations. There is a lot of inaccurate information that patients are presented in the mass media, and even more so, on the internet. With a better understanding of the maternal-fetal dyad, all practitioners should be able to help expecting parents find medically sound answers to their questions regarding the effects of anesthetic agents on their unborn child, what their surgical options are and how to best prepare.

Of utmost concern to any expecting mother is the possibility that surgery will cause harm to their baby. One of the most common questions involves teratogenicity caused by prenatal treatments. While it remains that maternal issues such as severe maternal hypoxia and hypotension pose the greatest risk to the fetus, there has now been considerable attention placed on the role of anesthetic agents on development.

There are several key factors that may influence teratogenicity, such as susceptibility, dose of the teratogenic substance, duration and timing of the exposure as well as genetic predisposition. Due to the substantial concern about the teratogenicity seen in animal models exposed to anesthetics, the U.S. Food and Drug Administration (FDA) issued an extensive statement to the public in December 2016 warning about the potential dangers of general anesthetics to the fetus. As this statement is now in the public realm, it is even more important for physicians to stay knowledgeable on the most recent literature.

Anesthetics primarily work by interfering with normal GABAa and NMDA receptor mediated activity to produce effective amnesia and unconsciousness. These same receptors are also believed to be involved in fetal central nervous system development. The most widely studied deleterious consequence of exposure to sedatives or anesthetics in immature animals is apoptosis (programmed cell death). Frequently used medications in anesthesia such as benzodiazepines and propofol as well as inhalational anesthetics have demonstrated varying degrees of apoptosis after exposure in animal models, however these apoptotic events have yet to show any correlation with future developmental abnormalities.

While concern about the effects of general anesthetics on the developing brain originates from animal observations, human studies have shown that a short duration of general anesthesia in the neonatal period has no profound developmental effects. Although no single anesthetic agent or medication has been shown to be neurotoxic to humans, a risk benefit ratio should always be implemented prior to administration of any anesthetic.

Another common question expecting mothers have is, “Can I have laparoscopic surgery?” Benefits of laparoscopic surgery include reduced surgical pain, decreased postoperative opioid consumption, decreased incidence of post-operative ileus and shorter length of hospital stay. Benefits unique to pregnant patients include decreased risk of fetal respiratory depression, as well as decreased postoperative maternal hypoventilation secondary to decreased opioid consumption, lower risk of wound complications and decreased risk of thromboembolic events. During pregnancy, insufflation pressures of 10-15 mmHg can be safely used for laparoscopy, however the pressure should be adjusted to the patient’s physiology.

A multidisciplinary team including surgeons, anesthesiologists, obstetricians and perinatologists should be involved in the decision to proceed with surgery. Urgent and emergent surgery should proceed without delay to minimize risk to the patient and the fetus. However, semi-elective procedures should be scheduled during the second trimester, when organogenesis is completed, and the risk of preterm labor is not as high as that during the third trimester.

Pregnant patients should undergo the same pre-operative evaluation as non-pregnant patients, and laboratories and other testing should be performed as indicated by the patient’s overall health and condition. In addition, the following risks should be taken into consideration:

1. Aspiration Prophylaxis: While gastric emptying is shown to be normal until active labor, pregnant women may be at a higher risk of aspiration. Aspiration prophylaxis should include a non-particulate antacid (bicitra) and H2-receptor blockers.

2. Difficult Intubation: Due to airway changes during pregnancy, pregnant patients are at increased risk of difficult intubation. Regional and neuraxial anesthesia should be considered when appropriate.

3. Thromboembolism: All pregnant patients undergoing surgery require mechanical and pharmacologic thromboembolic prophylaxis as pregnancy is a hypercoagulable state.

4. Patient Positioning: Depending on gestational age, the gravid uterus may apply pressure over major intra-abdominal vessels specifically in a supine position.

The final consideration for surgical procedures on the pregnant patient involves preparations for emergent delivery of the fetus. There is conflicting guidance for intraoperative fetal heart rate monitoring. Practices vary on whether to perform continuous versus intermittent monitoring, and whether to monitor any time during the pregnancy or only after fetal viability. What is not in question, however, is the need to have obstetrical support for women undergoing surgery once the fetus reaches 24 weeks’ gestation.

In conclusion, with good preparation, surgery may be performed successfully and with minimal risk to the pregnant patient. While some women may have misconceptions about the risks and future effects on their baby, they should be reassured that surgery during pregnancy occurs rather frequently, without significant complication.

Referring physicians should recommend specialists and hospitals that are experienced and are able to manage any possible complications, such as preterm delivery. While occurring infrequently, the fact that thousands of women do successfully undergo surgical procedures every year while pregnant should provide reassurance to our patients.

Suggested Reading:
Ceana Nezhat (ed), Kavic MS, Lanzafame RJ, Lindsay MK, Polk TM (assoc eds). Non-Obstetric Surgery during Pregnancy: A Comprehensive Guide. New York: Springer. In Press.


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