Should I collect pre-labs for mild hypertension at 37 weeks gestation?

Management of Mild Hypertension at 37 Weeks Gestation

Yes, you should collect pre-labs for mild hypertension at 37 weeks gestation, including complete blood count with platelets, liver function tests, renal function tests, and uric acid assessment. 1

Laboratory Assessment for Hypertension in Pregnancy

For a patient with mild hypertension at 37 weeks gestation, the following laboratory tests are essential:

• Complete blood count with platelets
• Liver function tests (AST, ALT)
• Renal function tests (creatinine, BUN)
• Uric acid
• Proteinuria assessment (protein/creatinine ratio)
• Fibrinogen levels (to evaluate for potential DIC) 1

These tests are crucial for several reasons:

1. To distinguish between gestational hypertension and preeclampsia
2. To assess end-organ damage
3. To establish baseline values for monitoring disease progression
4. To guide management decisions regarding timing of delivery

Clinical Context and Management

At 37 weeks gestation with mild hypertension (SBP 140-149 and DBP 90-99 mmHg), laboratory assessment is particularly important because:

• Immediate delivery is recommended for women with hypertension in pregnancy at ≥37 weeks gestation 1
• Laboratory abnormalities may indicate progression to preeclampsia, which would affect management decisions
• Blood pressure patterns in women with gestational hypertension show a non-linear increase over time, which may rapidly worsen 2

Decision Algorithm

1. Obtain laboratory tests as outlined above
2. Assess for preeclampsia (hypertension with proteinuria ≥30 mg/mmol or 0.3 mg/mg protein/creatinine ratio) 1
3. Consider delivery since the patient is at 37 weeks gestation 1
4. Monitor blood pressure closely while awaiting lab results

Important Considerations

• Normal blood pressure ranges vary by gestational age. At 35-37 weeks, the upper limits for normal blood pressure with home monitoring are 138/88 mmHg 3
• Development of severe hypertension (>160/110 mmHg) is a risk factor for cesarean section 2
• Even mild hypertension at 37 weeks warrants close monitoring as blood pressure can increase rapidly 2

Common Pitfalls to Avoid

• Pitfall #1: Failing to obtain complete laboratory assessment, which may miss early signs of end-organ damage
• Pitfall #2: Delaying delivery beyond 37 weeks in a patient with hypertension, which increases maternal and fetal risks
• Pitfall #3: Relying solely on automated blood pressure monitors for management decisions. The Omron HEM-705CP monitor identified >90% of mild hypertension but missed one-third of severe hypertension cases (>160/100 mmHg) 3
• Pitfall #4: Not considering that nulliparity, higher BMI, and elevated LDH can influence the course of blood pressure and may predict more rapid progression 2

In summary, laboratory assessment is essential for a patient with mild hypertension at 37 weeks gestation, both to guide immediate management decisions and to establish baseline values for monitoring.