Medical Emergencies During Pregnancy

Key Concepts

Asthma

The treatment goal for a pregnant woman with an acute asthma exacerbation is to prevent fetal hypoxia by keeping maternal oxygen saturation above 95%. Inhaled beta-agonists and corticosteroids are first-line emergency department treatment and are considered safe for use in pregnancy.

Cardiac Disease

Hypertensive emergency in pregnancy is defined as acute-onset persistent hypertension with systolic blood pressure greater than 160 mm Hg or diastolic blood pressure greater than 110 mm Hg that is persistent for greater than 15 minutes. In these cases, antihypertensive therapy should be administered as soon as reasonably possible, and no later than 30 to 60 minutes after diagnosis with a target blood pressure of 140 to 150 mm Hg systolic and 90 to 100 mm Hg diastolic. The drugs of choice are oral nifedipine, IV hydralazine, and IV labetalol.
The risk for acute coronary syndrome and acute myocardial infarction is increased in pregnant women compared to age-matched controls. The most common cause of AMI in the pregnant women is spontaneous coronary artery dissection. Treatment is similar to the nonpregnant agent, although P2Y12 receptor inhibitors should be avoided and fibrinolytic agent use should be carefully considered in women close to term.

Anemia

Anemia in pregnancy is defined as a hemoglobin less than 11. Serum ferritin is the most accurate lab value for diagnosing iron deficiency anemia in pregnancy. Women with mild iron deficiency anemia can be started on daily iron supplementation while those with severe iron deficiency in the second and third trimester can be referred for IV iron infusion.
Sickle cell disease causes maternal complications including more frequent pain crises, and increased risk of venous thromboembolism and preeclampsia. Treatment of pain crises is the same as in nonpregnant patients with the exception that hydroxyurea is contraindicated due to known teratogenicity.

Epilepsy

Gravid patients with epilepsy have a tenfold risk of death compared to pregnant women without epilepsy. Many antiepileptic drugs (AEDs) have known teratogenicity and levetiracetam and lamotrigine are considered the safest agents during pregnancy. Treatment of status epilepticus is with benzodiazepines followed by a phenytoin as first-line AED and levetiracetam as second-line AED.

Endocrine

Pregnant patients with type 1 diabetes mellitus (T1DM) are recommended to transition to insulin during gestation to achieve HgbA1C values <6%.
Hypoglycemia is most common in the first trimester, and up to 40% of pregnancies are marked with at least 1 episode of severe hypoglycemia.
Comorbid obesity increases the risk of cesarean section and venous thromboembolism.
Graves disease commonly rebounds in the immediate postpartum period with thyrotoxicosis.
Radioiodine is strongly contraindicated for the treatment of hyperthyroidism in pregnancy.
All gravid patients with new-onset nephrolithiasis should be screened for hypercalcemia. Treatment of hypercalcemia with bisphosphonates is contraindicated in pregnancy.

Psychiatric Disorders

Prenatal discontinuation of methamphetamines and other stimulants, although desirable, can cause depression and psychosis.
Maternal and neonatal outcomes in women on opioid agnostic therapy show decreased rates of neonatal abstinence syndrome (neonatal opioid withdrawal syndrome).

Inflammatory Disorders

Antiphospholipid syndrome (APS) in lupus patients is characterized by deep vessel clotting, pregnancy-related morbidity, and positive anticoagulant serum markers. Catastrophic APS has rapid-onset small vessel thrombosis, multiorgan dysfunction, and a high maternal mortality rate.

Renal Disease

Management of chronic kidney disease (CKD) in pregnancy can be treated with intensified hemodialysis (increased length of treatment time or increased frequency) to improve fetal outcome.
Patients post renal transplantation have fertility rates that return to normal within 6 months.

Infectious Disorders

Moderate to severe anemia in pregnancy in an HIV-infected mother should prompt a workup for tuberculosis.
During pregnancy, penicillin is the only known effective treatment for congenital syphilis, and pregnant patients with penicillin allergy should be desensitized and treated with penicillin.
Lamivudine given in late pregnancy to women with high viral loads of HBV DNA reduces viral transmission when given in conjunction with HBV vaccine and immune globulin.
Obstetric hemorrhagic complications, including DIC and shock and subsequent need for transfusion, are more common with HCV infection.

Foundations

The physiologic changes that occur in pregnancy may exceed the patient’s underlying compensatory mechanisms, resulting in initial symptom onset or rapid decompensation of medical illness during pregnancy. Certain chronic medical conditions also pose a serious threat to the mother’s health or result in a poor fetal outcome. Finally, some medical illnesses result in a difficult delivery or the need for special resuscitation measures in the neonate.

The incidence of pregnancy in chronically ill patients has been increasing because of improved survival of patients with diseases such as diabetes, epilepsy, renal failure, obesity, and various cancers. Also, the demographics of pregnancy are changing in that maternal age at the time of first pregnancy is increasing. Advances in assisted reproduction, including in vitro fertilization and oocyte donation, have made it possible for older women—including those who are postmenopausal—to become pregnant. Older pregnant women experience an increased rate of antepartum and intrapartum complications and are more likely to have comorbid conditions such as cardiovascular disease.

The recognition of an unexpected or even expected pregnancy may occur in the setting of the emergency department (ED), and many interventions are time-sensitive, requiring treatment in the ED. All emergency clinicians should have an understanding of critical diagnostic and treatment possibilities when encountering a pregnant patient with a preexisting illness.

Asthma

Asthma exacerbations occur in up to 45% of pregnant asthmatics with almost half of those exacerbations requiring rescue oral corticosteroids or hospitalization. Poorly controlled asthma is associated with an increased risk of preeclampsia or eclampsia, premature contractions, cesarean section, low birth weight, and small-for-gestational-age status. The risk of such complications varies with the severity of the disease and degree of control during pregnancy. Adverse perinatal outcomes increase with the severity of asthma during pregnancy. Controlling asthma during pregnancy leads to less intrauterine growth retardation and fewer adverse perinatal outcomes. It has been well documented that asthma may worsen, improve, or remain the same during pregnancy, but no studies have examined whether this is caused by changes in asthma triggers, treatment, or severity.

Maternal respiratory function changes can make it more difficult to recognize the decompensating pregnant asthmatic patient. Tidal volume and minute ventilation increase by 45% over the course of pregnancy resulting in an average P co ₂ of 32 mm Hg. The kidneys compensate and maintain an average bicarbonate level of 19 mEq/mL, which results in a compensated respiratory alkalosis with a serum pH between 7.40 and 7.45.

Many adverse perinatal outcomes associated with maternal asthma are thought to be due to fetal hypoxia. Thus, the overall goal of treatment is maintaining maternal oxygen saturations above 95%. Both the American College of Obstetrics and Gynecology (ACOG) and National Asthma Education and Prevention Program have clearly stated that it is safer to use asthma medications to treat pregnant women than to allow severe asthma symptoms and exacerbations to occur during pregnancy. Despite the support for aggressive asthma treatment from consensus guidelines, studies show variation in the amount of dispensed asthma medications before and during pregnancy.

The standard treatment for a pregnant asthmatic patient is the same as that for a nonpregnant patient with an asthma exacerbation. After history and the performance of a physical examination, the peak expiratory flow (PEF) or forced expiratory volume in 1 second (FEV ₁ ) should be measured. There is no significant change in the FEV ₁ / FVC ratio throughout pregnancy and a decline in these values is of concern. Patients with an FEV ₁ or PEF less than 50% of their predicted maximum are classified as having a severe exacerbation. An initial fetal assessment should be performed, including fetal heart tones and continuous electronic fetal monitoring with a biophysical profile if the pregnancy has reached viability. Supplemental oxygen should be given to all mothers with oxygen saturation below 95%.

Inhaled short acting β ₂ -agonists are the first-line treatment for an asthma exacerbation and can be given continuously, if needed, for a severe exacerbation. Adjunctive anticholinergic medications are considered and albuterol and can used as in nonpregnant patients. Long-acting selective β ₂ -agonists and inhaled corticosteroids can be added as controller medications on discharge from the ED. Multiple studies have shown no increased risk of adverse perinatal outcomes from inhaled corticosteroids. Budesonide is the preferred agent in pregnancy. Nonselective β-agonists such as epinephrine are generally avoided because of concern for uterine vasoconstriction. β-agonists are tocolytics and will often halt labor.

Oral corticosteroids are indicated for use in moderate to severe asthma exacerbations and should be prescribed for the same indications as in nonpregnant asthmatics. Despite these recommendations, in one study only 63% of pregnant women treated in the ED received systemic corticosteroids at discharge despite 100% of these women receiving inhaled β-agonists during their visit. There is weak evidence that oral corticosteroid use increases the risk of preterm delivery and low-birth-weight infants; there is also conflicting evidence of an increased risk of orofacial clefts. The benefits of oral corticosteroid use for avoiding fetal hypoxia greatly outweighs the risk of adverse perinatal outcomes and all expert guidelines recommend oral corticosteroid use.

Second-line agents for asthma control (e.g., cromolyn sodium) are considered safe in pregnancy. In limited studies, magnesium has been shown to improve respiratory function in pregnant females with severe asthma exacerbations without adverse fetal outcomes.

Cardiovascular Disorders

Foundations

Heart disease in pregnant women is the leading cause of nonobstetric maternal deaths. ^, The proportion of maternal deaths due to cardiovascular disease has increased as pulmonary hypertension, cardiomyopathies, aortic dissection, and myocardial infarction have become more prevalent in pregnant women. The increase in blood volume due to pregnancy, along with the increases in preload, cardiac output, and oxygen consumption, can worsen or reveal cardiac disease in pregnant women. Because the signs and symptoms of acute coronary syndromes and heart failure (e.g., shortness of breath, mild chest pain, edema) can be seen in normal pregnancies, these entities are especially difficult to diagnose.

Hypertension

Chronic Hypertension

The definitions of hypertension and hypertensive crisis differ for pregnant and nonpregnant patients, as do the blood pressure values at which to start treatment. As opposed to the American College of Cardiology (ACC)/American Heart Association definition, chronic hypertension in pregnancy is defined as hypertension (>140 mm Hg systolic or > 90 mm Hg diastolic) diagnosed prior to pregnancy or before 20 weeks’ gestation ( Table 174.1 ). Chronic hypertension in pregnancy increases the risk of superimposed preeclampsia, preterm delivery, intrauterine growth restriction, and cesarean section.

TABLE 174.1

Hypertensive Disorders of Pregnancy

Adapted from: Nishimura RA, Otto CM, Bonow RO, et al, ACC/AHA Task Force Members. 2014 AHA/ACC guideline for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation . 2010;129:e521e643.

	Chronic Hypertension	Gestational Hypertension	Preeclampsia	Chronic Hypertension With Superimposed Preeclampsia
Definition	Hypertension that antedates pregnancy ^a	Hypertension diagnosed after 20 wk of gestation in the absence of proteinuria or other evidence of preeclampsia	Hypertension that begins after 20 wk of gestation in association with new-onset proteinuria (>300 mg/24 hr) or symptoms below in the absence of proteinuria	Hypertension that antedates pregnancy in association with new-onset proteinuria
	Hypertension diagnosed before 20 wk of gestation		Decreased platelets, elevated liver transaminase levels, renal insufficiency, pulmonary edema	Sudden increase in proteinuria in woman with chronic hypertension ^a and proteinuria before 20 wk of gestation
				Hypertension that antedates pregnancy in association with sudden increase in blood pressure
	Comment—rarely, preeclampsia presents before 20 wk of gestation	Comment—may progress to preeclampsia; may also represent previously undiagnosed hypertension		Hypertension that antedates pregnancy in association with decreased platelets, elevated liver transaminase levels, renal insufficiency, pulmonary edema, or cerebral or visual symptoms

a Defined as blood pressure > 140 mm Hg systolic or > 90 mm Hg diastolic.

Chronic hypertension of pregnancy is categorized as mild hypertension (systolic blood pressure of 140–159 mm Hg or diastolic blood pressure of 90–109 mm Hg) or severe hypertension (systolic blood pressure greater than 160 mm Hg or diastolic blood pressure greater than 110 mm Hg). Previously there was agreement that mild hypertension of pregnancy did not require treatment. However, tight control of blood pressure (goal diastolic blood pressure less than 85 mm Hg) has been shown to lower the frequency of severe maternal hypertension. There is no difference in the risk of pregnancy loss, high-level neonatal care, or overall maternal complication between “tight” and “less-tight” blood pressure control groups. ACOG recommends that antihypertensive treatment be started when blood pressures are consistently higher than 160 mm Hg systolic and/or higher than 110 mm Hg diastolic. The European Society of Cardiology endorses treating chronic hypertension of pregnancy at 150/95 mm HG, though it sites a lack of evidence. Finally, the International Society for the study of Hypertension in Pregnancy endorses treating hypertension if blood pressures are consistently above 140/90 mm Hg.

The major risk posed by severe chronic hypertension is a progression to preeclampsia, which occurs in 25% of these pregnancies. Severe hypertension is associated with low birth weight, preterm delivery, elevated liver enzymes, and prolonged hospital stays as compared to women with chronic hypertension without severe hypertension. Antihypertensive drugs are effective in preventing this progression. The first-line oral agents for the treatment of chronic hypertension are labetalol 200 to 1200 mg/day in 2 to 3 divided doses, nifedipine XL 30 to 120 mg/day, and methyldopa 500 to 3000 mg/day in 2 divided doses.

Hypertensive Emergencies

All major society guidelines define a hypertensive emergency as acute-onset persistent hypertension with systolic blood pressure greater than 160 mm Hg or diastolic blood pressure greater than 110 mm Hg that is persistent for greater than 15 minutes. In these cases, antihypertensive therapy should be administered as soon as reasonably possible, and no later than 30 to 60 minutes after diagnosis. Goal blood pressure is within the range of 140 to 150 mm Hg systolic and 90 to 100 mm Hg diastolic in order to prevent loss of cerebral autoregulation. IV labetalol, IV hydralazine, and oral nifedipine are all considered first-line treatment, with oral nifedipine indicated when IV access has not yet been established ( Fig. 174.1 ).

Fig. 174.1, Urgent management of acute-onset hypertension in pregnancy.

In 2013, ACOG changed its diagnostic criteria for preeclampsia to no longer require proteinuria. In the absence of proteinuria, preeclampsia is diagnosed as hypertension in the presence of thrombocytopenia, impaired liver function, pulmonary edema, visual disturbances, or the development of renal insufficiency.

Cardiac Disorders

Acute Coronary Syndromes

In a United Kingdom Registry, cardiac disease was the largest indirect cause of maternal death with ischemic heart disease accounting for more than one-fifth of cardiac mortality. The mortality rate in pregnant women who have had an acute myocardial infarction (AMI) is from 5% to 7%. Pregnant women are two to four times more likely to have an AMI as compared to age-matched nonpregnant individuals. The number of older women becoming pregnant is increasing; pregnant women aged 40 years or older have a 30-fold greater risk for acute coronary syndrome (ACS) than pregnant women 20 years of age or younger. The incidence of AMI is highest during the last trimester and peripartum period with 21% of pregnancy related MIs occurring in the antepartum period.

Multiple factors are hypothesized to increase the risk of AMI in pregnancy, including a prothrombotic state, increased myocardial oxygen demand secondary to increased cardiac output and heart rate, and decreased oxygen-carrying capacity secondary to physiologic anemia, which may precipitate angina. Hypertension, thrombophilia, anemia, diabetes, advanced maternal age, multiparous state, and smoking increase the risk of pregnancy-associated AMI.

Most cases of ACS in pregnancy are related to causes other than atherosclerosis. The most common cause of ACS is spontaneous coronary artery dissection (SCAD) accounting for anywhere from 23% to 43% of pregnancy-related MIs. In one study, 90% of patients presenting with a SCAD related AMI were postpartum while in another study 72% of SCAD related AMIs were postpartum. ^, Pulmonary embolus, reflux esophagitis, biliary colic, and aortic dissection are all more common than myocardial ischemia during pregnancy and should be considered in the differential diagnosis of the pregnant patient who presents with chest pain. Initial signs and symptoms of AMI, such as chest pain and shortness of breath, are often attributed to the normal physiologic changes of pregnancy.

The diagnosis of ACS is similar to that in nonpregnant patients, with certain exceptions. Electrocardiographic changes sometimes occur in normal pregnancies and delivery. These include T wave flattening, T wave inversion (mainly in lead III), and nonspecific ST changes during pregnancy, as well as ST depression during labor induction for cesarean section. As a result, an additional evaluation may be necessary. Echocardiography is useful in the correlation of suspicious electrocardiographic findings with wall motion abnormalities. The enzymatic diagnosis of myocardial infarction is unchanged, and a serial troponin rise suggests myocardial ischemia, even in preeclampsia.

Treatment of AMI during pregnancy is similar in most respects to treatment of the nonpregnant patient, with survival of the mother as the goal. Standard treatments including antiplatelet agents, nitroglycerin, and beta blockers: antithrombotic agents are considered safe during pregnancy but the decision to use them should be made jointly by emergent consultation with a cardiologist and the patient’s obstetrician. Angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers, aldosterone antagonists, and statins are not advised until the postpartum period. Aspirin is the first-line antiplatelet agent. Clopidogrel has been studied in case reports with no adverse fetal outcomes and ACOG recommends that it can be used with caution, primarily after stenting. Ticagrelor, prasugrel, and bivalirudin are not recommended due to teratogenicity in animal studies. Heparin has long been the antithrombotic of choice for pregnant patients, although low-molecular-weight agents such as enoxaparin also do not cross the placenta and are considered efficacious and safe in pregnancy.

Cardiac catheterization with stenting is the treatment of choice for AMI in the pregnant patient and, with shielding, exposes the fetus to less than 1 radiation-absorbed dose (rad). However, both ACOG and the European Society of Cardiology recommend a conservative approach when considering cardiac catheterization in patients who may potentially have a coronary artery dissection. When a catheterization laboratory is unavailable, lifesaving thrombolytic therapy should not be withheld. Although thrombolytics do not cross the placenta, there is an increased risk of maternal hemorrhage and, in the setting of AMI caused by coronary dissection, thrombolytic use can worsen the dissection. Because thrombolytic therapy precludes major surgery and epidural anesthesia in the hours to days immediately after administration, one must carefully consider whether to use these agents in pregnant women who are close to term, especially if the need for cesarean delivery is anticipated.

In the setting of peripartum AMI, labor should be conducted with continuous monitoring of the mother’s hemodynamic status and fetal well-being. Assisted vaginal delivery is preferred unless there is an indication for cesarean section. Cesarean section avoids prolonged exertion by the mother but can subject the patient to general anesthesia if the use of antithrombotic agents precludes epidural catheter placement.

Valvular Heart Disease and Pulmonary Hypertension

Foundations

Valvular heart disease, including both native and mechanical valves, can lead to acute heart failure during pregnancy and is associated with both higher maternal and fetal mortality. The ability of patients to tolerate pregnancy without significant adverse effects depends on the type and severity of the lesion. Mild to moderate lesions (New York Heart Association [NYHA] classes I and II) are often associated with good outcomes for the mother and fetus. On the other hand, mitral stenosis (beyond class I), advanced aortic stenosis, and aortic and mitral lesions associated with moderate to severe ventricular dysfunction or pulmonary hypertension, as well as mechanical prosthetic valves requiring anticoagulation, can result in maternal mortality and require directed therapy and expert cardiology consultation.

Heart failure is the most common maternal complication in pregnancy with valvular heart disease, and women with cardiomyopathy, an NYHA functional class III or higher, pre-pregnancy heart failure, and pulmonary hypertension are at the highest risk. Diagnosing heart failure is challenging because women in the last months of pregnancy experience symptoms such as dyspnea on exertion, paroxysmal nocturnal dyspnea, orthopnea, and pedal edema that are identical to those of heart failure. Normal B-type natriuretic peptide (BNP) levels can be used to rule out heart failure in pregnant females but, because BNP levels increase twofold in pregnant females, a mildly elevated BNP level can be difficult to interpret.

Pulmonary Hypertension

Pregnancy is poorly tolerated by patients with pulmonary hypertension because the pulmonary circulation cannot cope with the increased stroke volume and cardiac output of pregnancy, causing pulmonary pressures to rise. This causes dyspnea, heart failure, and syncope. Mortality in pregnant women with pulmonary hypertension can approach 30%. Pregnancy is contraindicated, and patients early in pregnancy should be counseled about elective pregnancy termination.

The treatment of the pregnant patient with pulmonary hypertension focuses on diuresis and pulmonary vasodilation. Diuretics are indicated for the management of volume overload, and common diuretics—with the exception of spironolactone—are considered safe, although limited data exist regarding their effect on the fetus. Specific agents for treating pulmonary hypertension include endothelin receptor agonists (ERAs), phosphodiesterase inhibitors, and prostanoids. Phosphodiesterase inhibitors such as sildenafil and tadalafil, as well as the prostacyclin derivatives epoprostenol and treprostinil, are fetotoxic in animals; however, the benefits outweighs the risks, so they are regularly used in pregnancy. ERAs such as bosentan and ambrisentan are teratogenic.

Mitral Stenosis

Mitral stenosis is the most commonly encountered valvular lesion in pregnancy but is typically well tolerated except in moderate to severe disease. The increased resting heart rate and stroke volume in normal pregnancy increase the pressure gradient across the mitral valve and can cause symptoms of left heart failure, as well as atrial arrhythmias such as atrial fibrillation. The likelihood of maternal symptoms and worsening of cardiovascular status is directly related to the severity of disease.

Beta blockers are the mainstay of treatment for patients with symptomatic mitral stenosis in order to prevent tachycardia and maintain preload to overcome obstruction. Diuretics may also be used for patients with symptoms of heart failure. Surgical intervention is indicated for patients with refractory symptoms despite optimal medical management and in patients with pulmonary hypertension.

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