Obstetrics 8: Hypertension In Pregnancy Portal
Patient Assessment
History
Review obstetrical history, hypertension (HTN) prior to pregnancy, risk
factors for HTN during pregnancy, and symptoms consistent with the
onset of preeclampsia. As best possible, determine expected date of
delivery.
Exam
Check BP. Note pertinent physical findings including fluid
overload in the lungs, changes to the fundi of the eyes, body edema,
changes in neurological status such as LOC or seizure activity, and any
abdominal abnormalities.
Laboratory Data
Urinary proteinuria is the differentiating factor between
pregnancy-induced hypertension (PIH) and preeclampsia and should be
monitored regularly. Tests for evaluation include hemoglobin, platelet
count, peripheral smear, liver function test (AST), BUN/creatinine, and
uric acid. Consider fibrinogen level, fibrin split products, and PT/PTT
if the patient has a low platelet count. Obtain total protein and
24-hour urine for creatinine clearance if contemplating expectant
pharmacologic management or if the diagnosis is in doubt. LDH
and total bilirubin are helpful if hemolysis is occurring.
Treatment
Obtain high-risk obstetrical consultation.
Chronic
hypertension or PIH
Pharmacologic treatment is initiated in chronic HTN if the
diastolic BP is > 100 or in PIH when the BP reaches 160/110.
This decreases maternal complications but does not always prevent
preeclampsia, placental abruption, or IUGR. In acute PIH, keep the
diastolic BP > 90.
| BP Meds | Dose | Frequency |
| Hydralazine | 25 to 50 mg | four times daily |
| Aldomet | 250 to 500 mg | 2 to 4 doses/day (max 1 g/24 hour) |
| Labetolol | 100 to 300 mg | twice daily |
Use hydralazine and labetolol for acute management of BP >160/110.
Preeclampsia/Eclampsia
Complications increase at or near term, and delivery at 38 to 39 weeks
may be prudent. Patients with the onset of significant
proteinuria (> 250 to 300 mg/24 hour) or a sudden increase in BP
should be hospitalized. For those with fetal lung maturity or
where there is deterioration of mother or fetus, induce
delivery. If severe preeclampsia is present, do not delay
delivery regardless of pulmonary maturity; amniocentesis is rarely
indicated. Hypoglycemia must not be overlooked as it is the
most common cause of seizure death in eclamptic patients.
Severe preeclampsia includes:
- BP > 160-180/105-110 on 2 occasions at least 6 hours apart while at bed rest
- Qualitative proteinuria of 3+ or 4+ (> 5 g/24 hour)
- Oliguria < 500 cc/24 hour
- Neurologic symptoms present or visual disturbances
- Pulmonary edema
- RUQ or epigastric abdominal pain
- HELLP (hemolysis, elevated liver enzymes, low platelet < 100K) syndrome present. (However, this may be seen without the typical HTN and proteinuria.)
A major complication of preeclampsia or eclampsia is placental abruption. Treat all preeclampsia patients with magnesium sulfate (preferred drug) IV to prevent seizures. Secondary pharmacologic choices to control seizures are amobarbital or diazepam. The primary treatment of preeclampsia is delivery of the fetus; however, with extreme prematurity, seek expert consultation.
Inpatient Management
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Initiate continuous electronic fetal monitoring.
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Utilize continuous monitoring for fluid overload, convulsions, hypertensive crisis, or bleeding
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Start an IV with D5 0.45 NS at 100 to 125 cc/hour.
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Monitor I & O every hour.
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Keep the patient NPO on bed rest and with seizure precautions.
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Obtain vital signs every 15 to 30 minutes.
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Give magnesium sulfate IV load 4 g over 10 minutes, then 1 to 2 g/hour IV to reach a serum magnesium level of 6 to 8.
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Do not administer magnesium IV if urine output is < 40 cc/hour, if knee DTRs are absent, or if respirations are < 10 to 12/min.
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Treat magnesium overdose with 10 cc of a 10% calcium gluconate IV (1 g) over 3 minutes.
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Treat seizures with either magnesium sulfate (if the serum level is inadequate), amobarbital 250 mg IV, or diazepam 5 mg IV prn.
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For diastolic BP > 100-110, treat with Labetalol IV. Begin with 20 mg, followed at 10 to 15 minute intervals by 40 mg and then 80 mg, if needed, to a maximum cumulative dose of 220 mg. Hydralazine IV may also be used. Begin with 5 mg IV, followed by 5 to 10 mg boluses every 20 minutes to a maximum cumulative dose of 30 mg. Hydralazine is associated with more maternal hypotension, more placental abruption, more oliguria, and more adverse FHR patterns than occurs with the use of Labetalol. Nifedipine SL should not be used. (BP goal in patients without end-organ damage is 140-150/90-100. Goal BP in patients with end-organ damage is a BP < 140/90. Excess BP reduction may result in a reduction in placental circulation and fetal oxygenation.)1
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Check platelets every 4 to 6 hours and transfuse if < 50K.
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Check liver function tests daily in mild preeclampsia and four times daily if severe preeclampsia.
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Write an order to notify physician if patient exhibits hyperreflexia or clonus, has a diastolic BP > 110, or has a urine output < 40 cc/hour.
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Continue magnesium sulfate IV for 24 hours postpartum or until symptoms subside and diuresis ensues.
Stabilization and Transport Criteria
Refer the patient to a tertiary care center/Neonatal Intensive Care
Unit if gestation is < 34 weeks. Accomplish delivery
via amniotomy and/or induction or cesarean section when BP is
stabilized and symptoms are improved (6 to 8 hours after initiating
treatment) or once seizures are controlled. Observe the
neonate for hypermagnesium, hypocalcemia, respiratory depression,
hyporeflexia, drowsiness, and ileus. Avoid aminoglycoside
antibiotics in the neonate because of the possibility of precipitating
neuromuscular depression in this setting.
Reference
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August, P. Treatment of Hypertension in Pregnancy. In: Rose, BD, ED. UpToDate. Wellesley, MA, 2004.