Abigail Hankin-Wei
MEDICATION USE DURING PREGNANCY
Table 62-1 lists recommendations for drug use during pregnancy.
TABLE 62-1 Use of Medications in Pregnancy*
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DIABETES
Diabetes in pregnancy increases patients’ risk for complications of both pregnancy and diabetes, including preterm labor, spontaneous abortion, pyelonephritis, fetal demise, hypoglycemia, and diabetic ketoacidosis (DKA).
Insulin requirements increase throughout the pregnancy from 0.7 U/kg/d to 1.0 U/kg/d at term.
Ketosis develops more quickly and at lower glucose levels during pregnancy. Risk factors for DKA include poor compliance, hyperemesis, and use of sympathomimetic tocolytic agents.
DKA and hypoglycemia are treated the same as in the nonpregnant patient.
HYPERTHYROIDISM
Hyperthyroidism in pregnancy increases the risk of preeclampsia and neonatal morbidity. Clinical features mimic those of normal pregnancy, and may present as hyperemesis gravidarum. Propylthiouracil (PTU) is the treatment of choice; side effects include rash and agranulocytosis.
Thyroid storm presents with fever, volume depletion, and cardiac decompensation, and has a high mortality rate. Treat as in nonpregnant patients (see Chapter 133).
DYSRHYTHMIAS
Pregnancy and labor can precipitate dysrhthmias.
Supraventricular tachycardias should be treated with vagal maneuvers, then lidocaine, digoxin, procaina-mide, or verapamil in the usual doses.
Cardioversion has not been shown to be harmful to the fetus.
Amiodarone should be used only for life-threatening dysrhythmias not responsive to other measures, as iodine may lead to fetal neurotoxicity.
Use unfractionated or low-molecular-weight heparin for anticoagulation.
THROMBOEMBOLISM
Pulmonary embolism (PE) is the most common cause of maternal death in the developed world.
The incidence of deep venous thrombosis (DVT) ranges between 0.5% and 0.7%.
Factors associated with increased risk include advanced maternal age, increasing parity, multiple gestation, operative delivery (13- to 16-fold increase), bed rest, obesity, and hypercoagulable states.
Doppler compression ultrasonography is the preferred test for symptomatic DVTs; some suggest a combination of negative D-dimer and negative doppler compression ultrasound.
Perform lower extremity compression ultrasound in patients who do not meet low risk criteria. If negative for DVT, perform CT.
Chest CT exposes the fetus to less radiation than ventilation-perfusion scanning, but exposes maternal breast tissue to a higher dose.
Treatment of DVT and PE is with heparin or enoxa-parin; warfarin is contraindicated.
ASTHMA
Clinical features, diagnosis, and management are similar in pregnant and nonpregnant patients.
Acute therapy includes nebulized β2-agonists such as albuterol. Intravenous methylprednisolone and oral prednisone can be used in pregnancy.
Supplementary oxygen should be administered to keep O2 saturation above 95%.
Terbutaline 0.25 milligram SC every 20 minutes can be used if necessary. Epinephrine should be used only in the critically ill patient.
Criteria for intubation or admission are similar in pregnant and nonpregnant patients; standard agents for rapid-sequence intubation are used.
Peak expiratory flow rates are unchanged in pregnancy.
URINARY TRACT INFECTIONS
Urinary tract infection is the most common bacterial infection in pregnancy.
Simple cystitis may be treated for 3 days with slow release nitrofurantoin 100 milligrams PO, or an oral cephalosporin.
Patients with pyelonephritis should be admitted for IV antibiotics and hydration because of increased risk of preterm labor and sepsis. Antibiotic options include cefazolin 1 to 2 grams IV, or ampicillin 1 gram IV plus gentamicin1 milligram/kg IV.
Quinolones are contraindicated during pregnancy. Sulfonamides should be avoided in the third trimester, and trimethoprim should be avoided in the first trimester.
SICKLE-CELL DISEASE
Women with sickle-cell disease are at higher risk for miscarriage, preterm labor, and vaso-occlusive crises.
Clinical features, evaluation, and treatment are similar in pregnant and nonpregnant patients. Management includes aggressive hydration and analgesic therapy. Opioids should be used; nonsteroidal anti-inflammatory agents should be avoided after 32 weeks’ gestation. Hydroxyurea should be discontinued in pregnancy.
Parvovirus B19 may precipitate an aplastic crisis and is associated with development of hydrops fetalis.
HEADACHES
Warning symptoms to suggest a life-threatening etiology of headache include acute onset, postpar-tum onset, neurological deficits, and papilledema or retinal hemorrhages.
Migraines should be treated with acetaminophen, antiemetics, and opioids, if needed. Avoid ergot alkaloids and triptans.
SEIZURE DISORDERS
Altered pharmacokinetics during pregnancy may lead to increased frequency of seizures.
Management of a pregnant patient with a known seizure disorder is similar to that of a nonpregnant patient.
Status epilepticus with prolonged maternal hypoxia and acidosis has a high mortality rate for the mother and infant and should be treated aggressively with early intubation and ventilation. Place the patient in the left lateral decubitos position to maximize placen-tal oxygénation.
HIV INFECTION
All pregnant HIV-infected women beyond 14 weeks’ gestation should be on zidovudine therapy to reduce the risk of transmission to the fetus.
Patients with CD4 counts <200 should be on prophylaxis for Pneumocystis carinii pneumonia. Treatment of opportunistic infections is unchanged in pregnancy.
SUBSTANCE ABUSE
Cocaine use is associated with increased incidence of fetal death in utero, placental abruption, preterm labor, premature rupture of membranes, spontaneous abortion, intrauterine growth restriction, and fetal cerebral infarcts. Treatment of toxicity is unchanged in pregnancy.
Opiate withdrawal in pregnant women is treated with methadone or clonidine (0.1–1.0 milligram SL every hour until signs of withdrawal resolve, up to 0.8 milligram total).
Alcohol use contributes to increased rates of spontaneous abortion, low-birth-weight infants, preterm deliveries, and fetal alcohol syndrome.
Benzodiazepines, a category D class, are best avoided in early pregnancy, but can be used in the context of a clinically unstable patient in alcohol withdrawal.
DOMESTIC VIOLENCE
Approximately 4% to 20% of pregnant women are victims of domestic violence. They are at risk for placental abruption, uterine rupture, preterm labor, and fetal fractures. Rh immune globulin (Rhogam 300 micrograms IM) should be considered following blunt abdominal trauma in Rh-negative patients.
DIAGNOSTIC IMAGING IN PREGNANCY
The risk of radiation exposure varies with gestational age. The second to the eighth week postconception is the period of organogenesis, the most vulnerable period for birth defects. Mental retardation and other problems may occur after significant radiation exposures between weeks 8 and 25.
Data suggest that exposures <5 rads do not increase risk of fetal death, or neurological/growth retardation. Total doses from multiple exposures are summative, with a cumulative dose of 10 rads thought to be the threshold for human teratogenesis.
Ultrasound and magnetic resonance imaging exposures have not shown any teratogenic effects.
HYPERTENSION IN PREGNANCY
See Chapter 63.
OTHER THROMBOEMBOLIC EVENTS
See Chapter 27.
For further reading in Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7th ed., see Chapter 102, “Comorbid Diseases in Pregnancy,” by Pamela L. Dyne and Matthew A. Waxman.