Pre-eclampsia

Last revised by David Carroll on 07 Sep 2022

Pre-eclampsia is a disorder of pregnancy involving new-onset hypertension (systolic BP ≥140 mmHg or diastolic BP ≥90 mmHg) and involvement of one or more other organ systems.

Pre-eclampsia affects up to 8% of pregnancies 1.

  • diabetes mellitus 2
  • chronic hypertension 2
  • family history 2
  • nulliparity 2
  • advanced maternal age (>40 years) 2
  • obesity 2
  • anti-phospholipid syndrome (nine-fold increased risk)5
  • pre-eclampsia in prior pregnancy (seven-fold increased risk)5

Pre-eclampsia involves new-onset hypertension after 20 weeks gestation in pregnancy and up to 4-6 weeks postpartum with one or more of:

  • proteinuria
  • thrombocytopenia
  • renal impairment (doubling of serum creatinine)
  • liver impairment (doubling of hepatic transaminases)
  • pulmonary edema
  • headache or visual disturbance

The addition of tonic-clonic seizures is known as eclampsia.

The exact etiology of pre-eclampsia is still not fully understood. Although central to its development is believed to be the defective development of spiral placental arteries and subsequent placental ischemia.

Antenatal ultrasound may show intrauterine growth restriction due to placental insufficiency.

  • mean uterine artery PI may be above 95th percentile

Spectral Doppler indices measure in the internal carotid artery and more distal anterior circulation vasculature may demonstrate:

  • decreased resistive index (RI) and pulsatility index (PI) in the ophthalmic artery with higher peak early diastolic velocity and end diastolic velocity
    • an OA RI < 0.72 has been suggested to correlate with a higher risk of maternal/fetal complications 10
  • decrease in the RI and S/D ratio in the proximal cervical internal carotid artery
  • transcranial Doppler sonography of the maternal middle cerebral artery (MCA) may demonstrate:
    • decreased pulsatility index (PI) and resistive index (RI)
      • these changes have also been noted to be predictive of the subsequent development of pre-eclampsia in normotensive patients during the second trimester 7,8 
      • suggested cutoff values have been proposed, such as an MCA RI < 0.54 and MCA PI < 0.81 7

Cerebral edema and intracerebral bleeding have been reported in pre-eclamptic patients. The parieto-occipital region is the most frequently involved 3

When severe features are present temporizing measures may include the administration of intravenous magnesium sulfate and use of select antihypertensive medications to carefully decrease the blood pressure. The definite management for pre-eclampsia is delivery of the fetus. Pre-eclampsia is a major source of maternal and fetal morbidity and mortality 4.

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