Pre-eclampsia and Eclampsia

Original article by Tom Leach | Last updated on 27/8/2014
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Introduction

Pre-eclampsia and eclampsia are different stages of the same condition. Pre-eclampsia can result in eclampsia at any time. Eclampsia is immediately life-threatening and often symptomatic.
 
Pre-eclampsia is a condition characterised by increased blood pressure, proteinuria and often oedema during pregnancy. It is typically asymptomatic, and occurs after 20 weeks, although it rarely presents before 32 weeks – but when it does, it is associated with a worse prognosis.
  • Without prompt treatment eclampsia is deadly
  • Due to its asymptomatic nature, screening is very important
 

Epidemiology and Aetiology

  • Occurs in 1 in 2000 pregnancies (0.05%)
  • Risk factors include:
    • Primgravida
    • FH of pre-eclampsia
    • Previous history of pre-eclampsia
    • <155cm maternal height
    • Obesity / overweight mother
    • Maternal age <20 or >35
    • Past Hx of migraine
    • Hypertension
    • Underlying renal disease
    • Smoking reduces the risk(!)
 

Signs & Symptoms

Most commonly asymptomatic, but can cause:
  • Flu-like symptoms
  • Vomiting
  •  ↑pulse
  • Hyperreflexia and Clonus (>3 beats)
  • Seizures – indicated eclampsia
  • Headache
  • Visual disturbance
  • Bruising (Platelets <100)
  • Epigastric pain – HELLP – difficult to differentiate pain from that of reflux (common in pregnancy). HELLP does not respond to antacids, and may radiate to the back
  • Urea and creatinine – normal at first, may rise later
 

Pathology

It is a multisystemic disorder, resulting from a defect in the placenta. It is thought that placental factors that usually control blood flow to the fetus invade the mothers tissues, and alter arterial contractility.
  • These factors usually prevent vasodilation  - thus providing a constant stream of blood to the fetus. In pre-eclampsia, they also affect the maternal tissues.
  • In the maternal endothelium, the factors have a similar effect, and maternal BP rises in an attempt to compensate for this
 
As well as the maternal endothelium, the liver, kidneys and platelet count are often affected.
 

Diagnosis

There are several different criteria that can constitue a diagnosis:
  • Scenario One
    • Proteinuria (+1)
    • BP >140/90 – on two separate occasions > 6 hours apart
  • Scenario Two
    • BP >160/100 alone
  • Scenario three
    • BP rise > 30/20 over the booking BP
 

Prevention

  • Regular screening of BP and urine
  • Doppler ultrasound of the umbilical artery can identify mothers at risk, for whom prophylactic aspirin reduces the risk
 
Death usually results from:
  • Strokemost common
  • Hepatic failure
  • Renal failure
  • Liver failure
  • Women with pre-eclampsia can deteriorate extremely quickly! Within 24 hours…
 

Management

Delivery is the only cure – but – risk of eclampsia still exists for around a week after delivery
  • About 50% of eclamptic seizures occur after delivery
  • ½ of these are in the first 48hours
  • Management is possible up until and around delivery, but delivery should be planned as soon as the diagnosis is made

 

Antihypertensives

  • Give hydralazine IV in 5mg/20 mins until 20mg given
  • Give prophylactic H2- antagonists until after delivery
  • Catheterise and measure urine output
  • Restrict fluid intake to 80ml/hour (unless haemorrhage)
  • Avoid diuretics at all costs! – they reduce plasma volume
  • Antihypertensives reduce the risk of stroke but not the risk of death

 

Seizures

  • Seizures indicate the presence of eclampsia (i.e. it has progressed from pre-eclampsia)
  • Treat with magnesium sulphate 4g IV – with 100ml 0.9% saline.
  • Beware of respiratory depression!
  • After the initial dose, give a further 1g/24hours
  • Check resp rate and reflexes every 15 mins. Stop if <14/min or loss of reflexes
  • Calcium gluconate can reverse the effects of magnesium, if necessary

 

Delivery

  • Deliver as appropriate for gestation:
  • >34 weeks consider normal delivery
  • <34 weeks by caesarian
  • If <34 weeks give steroids before delivery
  • After the third stage of delivery, give 5U oxytocin IM or IV