Nonobstetric surgery in pregnant patients: Patient counseling, surgical considerations, and obstetric management

INTRODUCTION — The need for nonobstetric surgery can arise at any point in gestation. Urgent and emergency surgeries should not be delayed because the patient is pregnant, while elective procedures can wait until after delivery. With careful counseling, preparation, and postoperative care, most pregnant women can safely undergo nonobstetric surgery.

This topic will discuss the surgical considerations, patient preparation, and obstetric and surgical outcomes for patients who undergo nonobstetric surgery during pregnancy. Related content on the anesthesia management of these patients and the management of specific disorders in pregnant women is presented separately.

●(See "Anesthesia for nonobstetric surgery during pregnancy".)

●(See "Acute appendicitis in pregnancy".)

●(See "Gallstone diseases in pregnancy".)

●(See "Initial evaluation and management of major trauma in pregnancy".)

In this topic, when discussing study results, we will use the terms "woman/en" or "patient(s)" as they are used in the studies presented. We encourage the reader to consider the specific counseling and treatment needs of transgender and gender-expansive individuals.

PREVALENCE — Surgical procedures unrelated to pregnancy have been reported in approximately 0.7 to 1.6 percent of pregnant women [1,2]. Nonobstetric surgery most commonly involves the abdomen, mouth/dentition, nail/skin, and bone (table 1) [1]. The most common intraabdominal indications for nonobstetric surgery are appendicitis and biliary disease. In a cohort study of over 108,000 Danish women who underwent surgery while pregnant, the highest prevalence of surgery occurred in women aged ≥40 years, with elevated body mass index, high parity, current smoking history, and multiple gestations [2].

Discussions of appendicitis and gallstones in pregnancy, including surgical intervention, are presented elsewhere.

●(See "Acute appendicitis in pregnancy".)

●(See "Gallstone diseases in pregnancy".)

PATIENT COUNSELING — Evidence for counseling pregnant women requiring nonobstetric surgery comes from observational studies, expert opinion, and data extrapolated from cesarean delivery and other obstetric procedures.

Teratogenic effect — While the risk of teratogenesis from nonobstetric surgery is an area of active research, there is no strong evidence of increased risk from anesthetic agents, even when used during early pregnancy [3-5]. A detailed discussion of the fetal effects of anesthetics is presented in related content. (See "Anesthesia for nonobstetric surgery during pregnancy", section on 'Effects of anesthetics on the fetus and the pregnancy'.)

Risk of pregnancy loss (miscarriage) — When discussing the risk of pregnancy loss related to nonobstetric surgery, the clinician must first explain the baseline risk of pregnancy loss, which varies with the gestational age and the patient's medical history. Early pregnancy loss (eg, up to 12+6 weeks gestation) occurs in approximately 10 percent of all clinically recognized pregnancies [6-8]. Pregnancy loss in the second trimester (13 to 20 weeks gestation) occurs in less than 1 percent of patients [9,10].

For comparison, a systematic review of 54 studies including over 12,000 pregnancies in women undergoing nonobstetric surgery reported a 10.5 percent incidence of miscarriage during the first trimester, similar to baseline first-trimester risk, and an overall miscarriage incidence of 5.8 percent [4]. A major limitation of this study was lack of a control group. A study of an administrative database from the English National Health Service reported that, in adjusted analysis, surgery during pregnancy was associated with an increased risk of spontaneous abortion associated with hospitalization compared with no surgery during pregnancy (odds ratio 1.14, 95% CI 1.10-1.18) [1,11]. However, the incidence of spontaneous abortion not associated with hospitalization was not known for either patient group, and thus, the absolute risk of pregnancy loss could not be determined. A Danish national birth registry study reported a threefold increased risk of miscarriage for patients who underwent abdominal surgery during pregnancy compared with those who did not (adjusted hazard ratio 3.1, 95% CI 2.7-3.5) [12]. The risk was highest during the week following surgery and then levelled out after two weeks. Some studies reported higher rates of miscarriage in women who underwent first-trimester abdominal surgery [1]. However, it is not clear whether these higher rates were due to the surgery itself, the underlying maternal condition prompting the surgery (eg, trauma, infection, high fever), maternal characteristics (eg, smoking, older age), or other factors, such as excision of the corpus luteum early in gestation.

Obstetric outcomes following surgery — The overall increased risk of adverse obstetric events related to nonobstetric surgery during pregnancy appears to be low, although definitive conclusions are limited because much supporting data come from retrospective cohort studies [1,4]. It is difficult to separate the impact of the underlying disease and disease severity from that of the surgery itself. For example, a 2005 systematic review of 54 studies reported that fetal loss rates following appendectomy increased if peritonitis was present (2.6 percent without versus 10.9 percent with peritonitis) [4]. Comparisons are further limited by the grouping of surgeries that include a range of organ systems, pathology, and invasiveness; one might expect that the risks of open abdominal appendectomy in the setting of peritonitis differ from that of an uncomplicated laparoscopic cholecystectomy, but both would be considered abdominal procedures. Despite these limitations, a retrospective cohort study that evaluated over 47,000 nonobstetric surgeries identified from nearly 6.5 million pregnancies estimated the following increased overall risks [1]:

●Stillbirth – Every 287 procedures were associated with one additional stillbirth (stillbirth frequency of 0.6 percent without surgery and 0.9 percent with surgery)

●Preterm delivery – Every 31 surgeries were associated with one additional preterm birth (preterm delivery frequency of 7.5 percent without and 11.1 percent with surgery)

●Low birth weight infant – Every 39 operations were associated with one additional low birth weight infant (low birth weight frequency of 5.6 percent without and 8.6 percent with surgery)

●Cesarean delivery – Every 25 surgeries were associated with one additional cesarean delivery (cesarean delivery frequency of 23.9 percent without and 28.8 percent with surgery)

Issues specific to maternal cardiac surgery — A meta-analysis of 10 studies (published between 1990 and 2016 and including 154 women) attempted to define the risk of poor maternal or fetal outcome specific to women undergoing cardiac surgery utilizing cardiopulmonary bypass. Ninety percent of patients underwent urgent or emergency cardiac surgery, and most operations occurred in the second trimester. In this meta-analysis, risks of surgery during pregnancy were much greater than in earlier studies and included an 11 percent risk of maternal death, 33 percent risk of pregnancy loss (composite of spontaneous or induced abortion, fetal death, and stillbirth), 9 percent risk of maternal complications, and 11 percent risk of neonatal complications [13]. For every 100 pregnancies involving cardiac surgery with cardiopulmonary bypass, there were 28 episodes of preterm labor and/or delivery (combined outcome) and nearly 34 cesarean deliveries. For comparison, studies published prior to 1990 that assessed outcomes of cardiac surgery during pregnancy reported maternal mortality rates of 3 to 5 percent [14-16]. The reasons for the differences in reported maternal mortality between these studies are unclear, but the advancing stage of disease that necessitated urgent or emergency surgery may be one factor. Another factor may be hypothermia, which is often intentionally induced at the time of cardiopulmonary bypass. We find these updated numbers helpful when counseling women with cardiovascular disease who are pregnant, or may be considering pregnancy, because urgent or emergency surgery generally cannot be delayed until after delivery.

SURGICAL CONSIDERATIONS

Timing of surgery — Emergency surgery or surgery that is urgently required should be performed regardless of the trimester [3]. Nonurgent surgery that cannot wait until delivery (such as cholecystectomy for recurrent biliary obstruction without infection) is generally performed during the second trimester, if possible. Consistent with society guidelines, we advise delaying completely elective surgery until after delivery [3].

The rationale for this approach is based on the following:

●We prefer to minimize exposure of the fetus to surgery and medication during the first trimester of pregnancy, especially during organogenesis, as the safety of many drugs in pregnancy cannot be conclusively evaluated. In addition, common first-trimester adverse outcomes (eg, miscarriage, vaginal bleeding, fetal structural anomalies) may be erroneously attributed to surgery and anesthesia in the absence of other obvious causes. (See 'Risk of pregnancy loss (miscarriage)' above.)

●For abdominal surgery, we prefer to operate during the early second rather than the third trimester because of both technical and obstetric issues. The second-trimester uterus is still small enough to not obscure the operative field, and the risk of preterm labor may be lower when surgery is performed during the second trimester as compared with the third trimester [17].

Choice of abdominal approach — The surgical approach for abdominal procedures (laparoscopy or laparotomy) should be based on the skills of the surgeon, surgical needs and goals, and the availability of the appropriate staff and equipment. For abdominal surgery, laparoscopic surgery offers the same advantages to the pregnant woman as to the nonpregnant woman and can be performed safely during pregnancy. If a laparotomy is performed, the type of incision depends on the surgical procedure and gestational age. (See "Laparoscopic surgery in pregnancy".)

PATIENT PREPARATION

Preoperative evaluation — Pregnant patients who require surgery should be evaluated preoperatively in the same manner as nonpregnant patients. A thorough history should document underlying medical and obstetric conditions, and physical examination should include detailed assessment of the airway. Laboratory and other testing should be performed as indicated by the patient's medical problems and the proposed surgery. Additional preoperative testing is not indicated in an uncomplicated pregnancy. Additional preoperative care from the anesthesia team is discussed elsewhere. (See "Anesthesia for nonobstetric surgery during pregnancy".)

Fetal heart rate monitoring

Rationale — One purpose of fetal monitoring is to detect concerning changes in the fetal heart rate (FHR) that may be a result of reversible maternal factors not identified by maternal monitoring alone. Small decreases in maternal blood pressure, oxygenation, or uteroplacental blood flow may be enough to adversely impact the fetus. Potential interventions include administration of intravenous fluids, increase in oxygen concentration, administration of medications to increase maternal blood pressure, and changes in maternal position. However, because interpreting FHR tracings is challenging as there is a normal decrease in beat-to-beat variability while under general anesthesia and not all nonobstetric surgeries can be paused to allow for emergency cesarean delivery, the absolute benefit to the fetus is not known.

Discussions of FHR tracings and potential interventions are presented in detail elsewhere.

●(See 'Interpretation during surgery' below.)

●(See "Intrapartum category I, II, and III fetal heart rate tracings: Management".)

When to perform — The decision to use intermittent or continuous intraoperative fetal monitoring should be individualized, based on factors such as gestational age, type of surgery, and available resources. Consistent with society guidelines, we continuously monitor FHR in all viable fetuses (greater than 23 to 24 weeks of gestation) throughout surgery, if technically possible [3]. Intraoperative FHR monitoring can be achieved either by using an electronic FHR monitor or by Doppler ultrasound. While we perform continuous monitoring when possible, continuous FHR monitoring has not been shown conclusively to improve fetal outcome in women under general anesthesia. At a minimum, the FHR should be documented pre- and postoperatively, regardless of gestational age. The plan for intraoperative FHR monitoring and interpretation should be established preoperatively.

If continuous FHR monitoring is used, qualified personnel should be available to monitor and interpret the FHR throughout the surgery, and an obstetrician or clinician experienced in cesarean delivery should be readily available in case an emergency cesarean delivery is indicated [3]. Nonobstetric surgery after 23 to 24 weeks gestation should be performed in hospitals with pediatric services appropriate for the fetal gestational age. Appropriate resources should be immediately available in the operating room to facilitate resuscitation and stabilization of the premature newborn, if delivered. (See 'Interpretation during surgery' below and "Neonatal resuscitation in the delivery room".)

Interpretation during surgery — Medications used for general and regional anesthesia can cause changes in the FHR tracing that make interpretation challenging. All general anesthetic drugs cross the placenta and may result in minimal or absent FHR variability [18]. A systematic review of four studies including 155 pregnant women undergoing nonobstetric surgery reported minimal or absent FHR variability in most tracings and a decrease in FHR baseline of 10 to 25 beats per minute for women under general anesthesia [19]. Thus, other criteria must be used to identify nonreassuring tracings, such as those with persistent tachycardia in the absence of maternal fever, recurrent or prolonged FHR decelerations, recurrent late decelerations, or a sinusoidal pattern [20]. Before concluding that an FHR tracing is concerning enough to warrant emergency delivery, causative drug exposure should be excluded. As examples, opioids and magnesium sulfate can decrease heart rate variability, butorphanol can cause a sinusoidal pattern, and beta blockers and atropine can increase the FHR. The presence of moderate variability and/or FHR accelerations effectively excludes the presence of metabolic acidemia. (See "Intrapartum category I, II, and III fetal heart rate tracings: Management".)

Thromboprophylaxis — The hypercoagulable state of pregnancy increases the risk of a thromboembolic event in the postsurgical period. (See "Maternal adaptations to pregnancy: Hematologic changes".)

Consistent with published guidelines, we use thromboprophylaxis for all pregnant patients undergoing surgery [21]. We place pneumatic compression devices on all pregnant women prior to surgery and individualize the decision to use pharmacologic prophylaxis based on the expected extent and duration of the planned procedure and the patient's risk factors for venous thrombosis in addition to the pregnancy (eg, thrombophilia, prolonged immobilization, past history of venous thrombosis, malignancy, diabetes mellitus, varicose veins, paralysis, maternal age, or obesity). Risk stratification for venous thromboembolic disease and suggested prophylaxis are discussed separately.

●(See "Venous thromboembolism in pregnancy: Prevention", section on 'Cesarean section'.)

●(See "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients".)

After surgery, we encourage early mobilization to minimize the risk of deep vein thrombosis and continue thromboprophylaxis until the patient is fully ambulatory without prolonged periods of immobility. (See "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients", section on 'Duration'.)

Antibiotic prophylaxis — The need for antibiotic prophylaxis depends on the specific procedure. (See "Antimicrobial prophylaxis for prevention of surgical site infection in adults".)

Antibiotics with a good safety profile in pregnant women include the cephalosporins, penicillins, erythromycin (except estolate), azithromycin, and clindamycin. Aminoglycosides are relatively safe but carry a risk of fetal (and maternal) ototoxicity and nephrotoxicity. The use of antibiotics in pregnant women is presented in detail separately. (See "Prenatal care: Patient education, health promotion, and safety of commonly used drugs", section on 'Antibiotics'.)

Glucocorticoid administration — Administration of a course of antenatal glucocorticoids 24 to 48 hours prior to surgery for patients between 24 and 34 weeks of gestation can reduce perinatal morbidity/mortality if preterm birth occurs [3]. The decision to give glucocorticoids, and potentially delay surgery for 24 to 48 hours, must balance the urgency of the surgery with the obstetrician's estimate of the risk of preterm birth because of the underlying disease or the planned procedure. (See "Antenatal corticosteroid therapy for reduction of neonatal respiratory morbidity and mortality from preterm delivery".)

Antenatal glucocorticoids should be administered with caution in the setting of systemic infection (such as sepsis or a ruptured appendix) because they may impair the ability of the maternal immune system to contain the infection.

Tocolytic agents — There is no proven benefit to routine administration of prophylactic perioperative tocolytic therapy. Tocolytics are indicated for treatment of preterm labor until resolution of the underlying, self-limited condition that may have caused the contractions. Minimizing uterine manipulation may reduce the risk of development of uterine contractions and preterm labor. (See "Inhibition of acute preterm labor".)

Administration of magnesium sulfate — In general, nonobstetric surgery is not intended to end in delivery. However, in cases where delivery may be required, such as trauma surgery, magnesium sulfate administration is considered for appropriate fetuses. (See "Neuroprotective effects of in utero exposure to magnesium sulfate".)

POSTOPERATIVE CARE

Maternal care and fetal assessment — Immediate postoperative care of the mother and fetus is presented in related text. (See "Anesthesia for nonobstetric surgery during pregnancy", section on 'Postoperative care'.)

Role of progesterone supplementation — The corpus luteum is required for progesterone production up to approximately seven to nine weeks of pregnancy, at which time luteal support is shifted from the ovarian corpus luteum to the placenta (called the luteoplacental shift) [22,23]. Removal of the corpus luteum prior to the luteoplacental shift will result in progesterone withdrawal and possible pregnancy loss [22-27]. Thus, we recommend postoperative progesterone supplementation when the corpus luteum is removed or disrupted prior to seven to nine weeks of gestation. Treatment options include progesterone 50 to 100 mg vaginal suppository every 8 to 12 hours or a daily intramuscular injection of 1 mL (50 mg) progesterone in oil; oral progesterone appears to be less effective [25]. The authors use vaginal progesterone 100 mg every 12 hours until 10 to 12 weeks. A small, seminal study showed that removal of the corpus luteum up to 47 days of pregnancy (dating by last menstrual period) resulted in a high rate of abortion; however, removal of the corpus luteum after 61 days only resulted in a transient decrease in progesterone, without a high rate of abortion [22]. Others have reported similar findings [23].

The efficacy of preoperative progesterone supplementation for prevention of possible procedure-related preterm labor later in gestation has not been studied. The indications for progesterone supplementation in women at risk for preterm birth are discussed separately. (See "Progesterone supplementation to reduce the risk of spontaneous preterm labor and birth".)

OUTCOME OF SURGERY — It is unclear whether the risk of surgical morbidity or mortality from nonobstetric surgical procedures is increased for pregnant women compared with nonpregnant women. However, as delaying nonelective surgical intervention increases the risks of complications, particularly for infection and venous thromboembolism, pregnant women who require surgical procedures should be advised to proceed and avoid delay.

Data comparing outcomes of surgery in pregnant and nonpregnant patients are conflicting, with some studies showing no difference in postoperative complications [28-30] and others showing an increase in complications in pregnant patients [31]. Examples of such studies include the following:

●A retrospective cohort study that matched over 2500 pregnant women to nonpregnant controls undergoing general surgical procedures in the United States reported no differences in the 30-day mortality rates (0.4 versus 0.3 percent) and morbidity rates (6.6 versus 7.4 percent) [28]. Although the pregnant women were more likely to have emergency surgery compared with nonpregnant controls (51 versus 13 percent), the rates of poor outcomes were not increased. The increased morbidity typically associated with emergency surgery may have been ameliorated by the significantly younger age of the pregnant women compared with the nonpregnant women (30 versus 53 years). It is not known if this finding would be the same in a cohort of older pregnant women.

●By contrast, a cohort study of over 5500 pregnant women in Taiwan reported a nearly fourfold increased rate of in-hospital maternal mortality (0.82 percent for pregnant women compared with 0.21 percent for nonpregnant women, time period not specified); a 2.5-fold increased risk of admission to the intensive care unit; and increased risks of postoperative septicemia, pneumonia, and urinary tract infection for pregnant women undergoing nonobstetric surgery compared with nonpregnant women [31]. In this study, nearly one-half of the women were younger than 30 years of age. The amount of time elapsed until surgery was not reported. A concern with such a finding would be that the finding may be related to the management of the disease state prior to surgery differing between pregnant and nonpregnant women as opposed to the impact of the surgery itself. It is not known if the differences in outcomes between the two cohort studies reflect differences in the study designs, populations, care protocols, or other factors.

While available data on the risk of surgery in pregnant women are conflicting, surgical delay has been linked to worsened outcomes, particularly for infectious surgical indications such as appendicitis and cholecystitis. As an example, a study of over 7100 women with appendicitis in pregnancy reported that conservative medical management was associated with an increased risk of septic shock (adjusted odds ratio [aOR] 6.3, 95% CI 1.9-20.8), venous thromboembolism (aOR 2.5, 95% CI 0.9-7.4), and peritonitis (aOR 1.6, 95% CI 1.3-2.1) compared with appendectomy [32]. Similarly, in a study of pregnant women with cholecystitis, women managed surgically had lower maternal complication rates (4 versus 16 percent) and fetal complication rates (6 versus 16 percent) compared with women treated medically [30]. In such nonrandomized studies, however, population differences and other potential confounders may be large contributors to differences.

DELIVERY ROUTE AFTER NONOBSTETRIC SURGERY — Cesarean delivery is performed for standard obstetric indications in patients who have had recent surgery; the presence of a recent abdominal incision does not preclude pushing in the second stage of labor [33].

SUMMARY AND RECOMMENDATIONS

●Surgical procedures unrelated to pregnancy have been reported in up to 1.6 percent of pregnant women. Nonobstetric surgery most commonly involves the abdomen, mouth/dentition, nail/skin, and bone (table 1). (See 'Prevalence' above.)

●Evidence for counseling pregnant women requiring nonobstetric surgery comes from observational studies, expert opinion, and data extrapolated from cesarean delivery and other obstetric procedures. While the risk of teratogenesis from nonobstetric surgery is an area of active research, there is no strong evidence of increased risk from anesthetic agents. Similarly, the risk of pregnancy loss does not appear to be significantly increased. (See 'Patient counseling' above.)

●The overall increased risk of adverse obstetric events related to nonobstetric surgery during pregnancy appears to be low, although definitive conclusions are limited because much supporting data come from retrospective cohort studies. (See 'Obstetric outcomes following surgery' above.)

●Urgent or emergency surgery should be performed regardless of the trimester. Nonurgent surgery that cannot wait until after delivery is generally performed in the early second trimester. We delay elective surgery until after delivery. (See 'Timing of surgery' above.)

●The fetal heart rate should be documented pre- and postoperatively. The decision to use intermittent or continuous intraoperative fetal monitoring should be individualized, based on factors such as gestational age, type of surgery, and available resources. We continuously monitor all viable fetuses (greater than 23 to 24 weeks of gestation) throughout surgery, if technically possible. If continuous monitoring is used, personnel capable of interpreting the heart rate should be available to monitor and interpret the FHR. An obstetrician or clinician experienced in performing an emergency cesarean delivery should be readily available. (See 'Fetal heart rate monitoring' above.)

●We recommend pneumatic compression devices for all pregnant patients who undergo surgery (Grade 1B). We individualize pharmacologic thromboprophylaxis based on risk of perioperative thrombosis. (See 'Thromboprophylaxis' above.)

●The decision to give glucocorticoids, and potentially delay surgery for 24 to 48 hours, must balance the urgency of the surgery with the obstetrician's estimate of the risk of preterm birth because of the underlying disease or the planned procedure. (See 'Glucocorticoid administration' above.)

●We recommend postoperative progesterone supplementation when the corpus luteum is removed prior to seven to nine weeks of gestation (Grade 1C). (See 'Role of progesterone supplementation' above.)

●It is unclear whether the risk of surgical morbidity or mortality from nonobstetric surgical procedures is increased for pregnant women compared with nonpregnant women. However, as delaying nonelective surgical intervention increases the risks of complications, particularly for infection and venous thromboembolism, pregnant women who require surgical procedures are advised to proceed and avoid delay. (See 'Outcome of surgery' above.)

●Cesarean delivery is performed for standard obstetric indications in patients who have had recent surgery; the presence of a recent abdominal incision does not preclude pushing in the second stage of labor. (See 'Delivery route after nonobstetric surgery' above.)