Gestational Hypertension

written by Reuben Kiggundu, medical student, Makerere University

Gestational hypertension, or pregnancy-induced hypertension, develops >20 weeks gestation in 6-8% of all pregnancies.

The next step in the disease progression is proteinuric hypertension, previously known as pre-eclampsia. Protein levels >300 mg/L, suggests the blood pressure is significant enough to cause end-organ damage.

The most serious form of gestational hypertension is eclampsia, or seizures resulting from hypertension.

 

 

Causes and Risk Factors

While the cause of preeclampsia is unknown, identified risk factors include:

Increased incidence observed in patients using barrier contraception, in multiparous women conceiving with a new partner, and in nulliparous women, suggests an immunologic role.

 

 

Signs, Symptoms, and Diagnosis

 

  • history
  • physical exam
  • lab investigations

History

Symptoms of preeclampsia include:

  • headache
  • visual disturbances (blurred vision, scotomata)
  • epigastric pain
  • nausea and vomiting
  • decreased urine output
  • edema
  • tremulousness, irritability
  • somnolence

Eclampsia symptoms include:

  • worsening headache, visual changes, and epigastric pain
  • seizures

Physical Exam

Hypertension in a previously normotensive woman should be greater than:

  • Systolic 140mmHg, or 30 mmHg above preterm levels
  • Diastolic 90mmHg or 15 mmHg above preterm levels

Diagnosis requires two such abnormal BP measurements recorded at least 6 hours apart.

 

Other findings can include:

  • diffuse edema
  • papilledema
  • hyperreflexia/clonus
  • petechiae and bruising can suggest coagulopathy
  • right upper quadrant or mid-epigastric tenderness
  • coma

Fetal evaluation

  • movement
  • non-stress test
  • ultrasound for growth
  • biophysical profile
  • doppler flow studies

Lab Investigations

  • hemoglobin (often elevated due to hemoconcentration)
  • platelets
  • blood film for hemolysed cells
  • PTT, INR, fibrinogen, D-dimer
  • ALT, AST, LDH
  • creatine, uric acid

urine dipstick

  • 2+ significant
  • 3-4+ severe

24 hour urine collection or a protein/creatinine ratio

  • >300mg/24hr
  • >5g/24hr severe

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Pathophysiology

While the etiology of gestational hypertension is unknown, we know increased vasoconstriction occurs due to an imbalance of thromboxane (vasoconstrictor) and prostaglandin (vasodilator).

 

Improper placental development results in placental vascular endothelial dysfunction and a relative uteroplacental insufficiency. The vascular endothelial dysfunction results in increased permeability, hypercoagulability, and diffuse vasospasm. Increased vasospasm leads to concentrated blood.

 

Increased cardiac output observed during pregnancy.

 

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Treatments

Blood pressure and proteinuria should be closely followed. Delivery of the baby is the definitive treatment. Consider induction if over 37 weeks GA.

 

Bed rest in the left lateral decubitus position may be helpful but is unproven. Sodium and fluid restriction not as helpful as in essential hypertension.

 

Medications

Always get repeat readings and assess the status of the baby before instituting medication treatment.

Hydralazine the drug of choice; other drugs include methyldopa, labetolol, nitroprusside, nifedipine.

Avoid diuretics and ACE inhibitors due to risk of uterine ischemia and teratogenicity for the ACE.

 

Magnesium sulfate (MgSO4) can be used for prevention of seizures in precarious circumstances. Management of seizures - magnesium sulfate, phenytoin, diazepam.

 

 

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Consequences and Course

Seizures, with potential attending stroke, and HELLP syndrome are important complications.

 

If treated early, the prognosis is usually good. However the following can also occur:

Further outpatient care and followup is important. Risk of seizures is highest in first 24 hours postpartum, requiring continued MgSO4 for 12-24 hours. Seizures can occur up to 30 days postpartum.

 

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Resources and References

Merck manual of medical information.
Fundamentals of Obstetrics and Gynecology.