Does Anesthesia Increase the Risk to the Parturient Undergoing Nonobstetric Surgery?

INTRODUCTION

It is estimated that 0.75% to 2% of pregnant women in developed countries undergo nonobstetric surgery during the course of parturiency; approximately 42% undergo surgery in the first trimester, 35% in the second, and 23% in the third trimester. ^, Thus nonobstetric surgery during pregnancy accounts for approximately 75,000 to 80,000 procedures per year in the United States alone. ^, Procedures for appendicitis, cholelithiasis, traumatic injuries, ovarian torsion, cervical incompetence, and breast disease are the most prevalent in this patient population. Often, these procedures are indicated.

Despite overall favorable results in these patients, there is a strong aversion to the use of drugs and the performance of procedures during pregnancy because of possible complications. ^, Of ultimate concern to both patients and health care providers is the effect of anesthetic agents on fetal development. Traditional teachings also suggest an increased risk for pregnancy loss when surgery is performed during the first trimester and an increased risk for preterm birth when it is performed during the third trimester; thus there is a preference for surgical procedures during the second trimester because of its minimal risk. Nevertheless, there is still limited evidence and quality data from the medical literature supporting the recommendation to avoid necessary nonurgent surgery in the parturient that would have been clearly indicated in the identical, nonpregnant patient. Literature questioning this dogma is beginning to emerge as recommendations mostly stem from old data in women who obtained surgery when diagnostic testing, surgical techniques, and perioperative maternal–fetal care were very different from today. Several reasons make the relevance of existing data to current practice questionable. These include the existing challenge in performing research studies during the period of parturiency; the low numbers of procedures done in this patient population; the tendency to combine data from significantly different types of surgery into a single cohort when reporting outcome data during pregnancy ; the lack of clear delineations in medical journals between maternal outcomes and pregnancy outcomes when assessing perinatal risks of surgery compared with no surgery ; and the lack of appropriate control groups for comparison where pregnant women with surgical disease are compared with the general population of pregnant women instead of matched women with the same condition.

This chapter explores the current evidence on the effect of anesthesia on the parturient undergoing nonobstetric surgery in the light of traditionally accepted but, perhaps, scientifically questionable conclusions regarding risks for surgery during pregnancy.

OPTIONS

Current guidelines suggest that all surgical procedures performed during pregnancy should be either urgent or emergent. There is a general reluctance to perform necessary surgical (diagnostic or therapeutic) procedures during pregnancy because of the major risks described in the literature. Key options or alternatives revolve around the timing of surgery (i.e., whether surgery should be delayed until later in gestation considering the risk and benefits of the surgery) and the agents used.

EVIDENCE

Both the American Society of Anesthesiologists (ASA) and the American College of Obstetricians and Gynecologists (ACOG) agree that the paucity of data does not allow for specific recommendations regarding nonobstetric surgery during pregnancy. This can be attributed to the inability to conduct large randomized controlled trials (RCTs) in this patient population. Important anesthetic and surgical issues in this patient population include risk for adverse pregnancy outcomes after nonobstetric surgery, whether anesthesia is toxic and/or teratogenic to the fetus, fetal monitoring during surgery, preterm labor after nonobstetric surgery, and use of laparoscopy during pregnancy.