• Clinical science

Hypertensive pregnancy disorders

Abstract

Hypertensive pregnancy disorders are the most common medical complication during pregnancy. There are four major types of hypertensive pregnancy disorders. The most common is gestational hypertension, also referred to as pregnancy-induced hypertension (PIH), which occurs after 20 weeks gestation. Preeclampsia is a form of hypertensive pregnancy disorder with multiorgan involvement. It is characterized by new-onset hypertension and proteinuria after 20 weeks gestation. Risk factors include nulliparity, a positive family history, and African-American ethnicity. Eclampsia is a severe form of preeclampsia, characterized by new-onset of eclamptic seizures (grand mal seizures). Preeclampsia may also progress to the life-threatening HELLP syndrome, which is characterized by Hemolysis, Elevated Liver enzymes, and Low Platelet count.

Hypertensive pregnancy disorders are usually diagnosed in the course of regular prenatal care, which includes regular surveillance of blood pressure, weight and urine tests. Initial treatment for all hypertensive pregnancy disorders consists of maternal and fetal monitoring until delivery is feasible. Antihypertensive treatment (e.g., labetalol, hydralazine) is indicated in severe hypertension. Magnesium sulfate is important to prevent seizures in severe preeclampsia and eclampsia. Patients with eclampsia and HELLP syndrome require immediate stabilization followed by delivery if the pregnancy is ≥ 34 weeks gestation. Delivery is the only curative option for preeclampsia and eclampsia, which are both associated with increased maternal and fetal morbidity and mortality. HELLP syndrome has a poor fetal prognosis.

Definition

These disorders are on a spectrum from less to more severe, and occur after 20 weeks gestation.

Gestational hypertension can only be diagnosed if the patient was normotensive prior to 20 weeks gestation! Otherwise, high blood pressure during pregnancy is classified as chronic hypertension.

References:[1][2][3][4]

Epidemiology

References:[2][5][6][7][8][9]

Epidemiological data refers to the US, unless otherwise specified.

Etiology


Smoking actually decreases the risk of developing preeclampsia!

References:[10][11][4][12]

Pathophysiology

  • Overview: Multiple maternal, fetal, and placental factors are involved in placental hypoperfusion, which leads to maternal hypertension and other consequences.
    • Abnormal placental (or trophoblast) implantation or development in the uterus → hypoperfusion of placenta and fetus (see “Placenta” in the learning card pregnancy for normal placenta formation)
    • Arterial hypertension with systemic vasoconstriction causes placental hypoperfusion → release of vasoactive substances → ↑ maternal blood pressure to ensure sufficient blood supply of the fetus
    • Systemic endothelial dysfunction causes placental hypoperfusion → placental release of factors endothelial lesions that lead to microthrombosis
  • Consequences of vasoconstriction and microthrombosis
Organ Pathomechanism Disorder Occurrence
Kidney
  • Glomerular endothelial dysfunction and hypertension-induced vasoconstriction
Lung
Liver
  • Vasoconstriction and microthrombotic obstruction of liver sinusoids → liver cell damage
CNS
  • Hypertension-induced vasoconstriction and endothelial damage → disruption of cerebral microcirculation with microthrombi → vasospasms in the CNS
Blood
  • Systemic microthrombi and vasoconstriction → overactivation of the coagulation system and platelet consumption
  • Microangiopathic hemolysis

Normal placenta formation: cytotrophoblast implant into the uterus (decidua and myometrium) → infiltrate the endothelium and tunica media of the maternal spiral arteries → the spiral arteries remodel into large vessels with lower resistance → ensures sufficient blood supply for the fetus

References:[11][3][4][8][13][14][15]

Clinical features

Gestational hypertension

  • Asymptomatic hypertension
  • Nonspecific symptoms (e.g., morning headaches, fatigue, dizziness) can occur.

Preeclampsia

  • Onset: 90% occur after 34 weeks of gestation

Preeclampsia without severe features

  • Usually asymptomatic
  • Nonspecific symptoms may include:
    • Headaches
    • Visual disturbances
    • RUQ or epigastric pain
    • Rapid development of edema
  • Hypertension
  • Proteinuria

Preeclampsia with severe features

  • Severe hypertension (systolic ≥ 160 mmHg or diastolic BP ≥ 110 mmHg)
  • Proteinuria, oliguria
  • Headache
  • Visual disturbances (e.g., blurred vision, scotoma)
  • RUQ or epigastric pain
  • Pulmonary edema
  • Cerebral symptoms (e.g., altered mental state, nausea, vomiting, hyperreflexia, clonus)

HELLP syndrome

Eclampsia

Deterioration with headaches, RUQ pain, hyperreflexia, and visual changes are warning signs of a potential eclamptic seizure!

Hypertensive pregnancy disorders may be intrapartum or postpartum. In some cases, eclamptic seizures may occur postpartum.

References:[10][11][1][2][4][6][8][15][9][16]

Diagnostics

Prenatal screening for hypertensive pregnancy disorders

Early detection to prevent maternal and fetal complications.

Initial workup

Diagnostic criteria
Gestational hypertension
  • Hypertension (> 140/90 mmHg) diagnosed after 20 weeks gestation
Preeclampsia Preeclampsia without severe features
Preeclampsia with severe features
HELLP syndrome
  • The following features must be present:
    • H = Hemolysis
    • EL = Elevated Liver enzymes
    • LP = Low Platelets
Eclampsia
Chronic hypertension

Fetal assessment

References:[1][4][15][17][18][19]

Differential diagnoses

Differential diagnosis of eclampsia

Seizure disorders during pregnancy

Differential diagnosis of HELLP syndrome

Causes of thrombocytopenia and liver impairment during pregnancy

  • Thrombotic microangiopathy (TTP, HUS)
  • Fulminant viral hepatitis

Acute fatty liver of pregnancy

Intrahepatic cholestasis of pregnancy

An early therapy with ursodeoxycholic acid reduces the risk of preterm birth and stillbirth.

References:[2][8][9][16][20][21][22][23]

The differential diagnoses listed here are not exhaustive.

Treatment

Gestational hypertension and Preeclampsia without severe features

ACE inhibitors and angiotensin-receptor blockers (ARB) are contraindicated during pregnancy due to their teratogenic effect!

Preeclampsia without severe features can progress to preeclampsia with severe features within days! Close monitoring is vital!

Preeclampsia with severe features

Delivery is the only cure for preeclampsia.

Eclampsia

  • Stabilization
  • Expectant management in patients < 34 weeks gestation to allow time for corticosteroid administration can be considered in select cases, but the safety and benefits of this approach have not been confirmed (see “Expectant management” of preeclampsia with severe features above)
  • Delivery: once the mother is stable and seizures have stopped.

Delivery is the only cure for eclampsia.

HELLP syndrome

References:[11][6][8][16][17][24][25]

Complications

ARDS and cerebral hemorrhage are the most common causes of death.

References:[10][11][2][26][27][28]

We list the most important complications. The selection is not exhaustive.

Prognosis

The prognosis of hypertensive pregnancy disorders depends on the severity of the condition and the complications that occur.

References:[10][2][4][8][9][16]

Prevention

  • Prophylactic low-dose ASA PO from 12–14 weeks gestation for patients with a high risk of developing preeclampsia

References:[29]