Authors: Jenni Cooper, Naomi Primrose / Editor: Lauren Fraser / Codes: ACCS LO 2, ObC11, ObC6, ObP3, SLO1Published: 04/02/2021

Pre-eclampsia is a hypertensive syndrome occurring during pregnancy which is characterised by new onset hypertension occurring after 20 weeks of gestation and usually associated with proteinuria.  It occurs in approximately 6% of pregnancies.

Many patients with pre-eclampsia will be diagnosed when asymptomatic through routine screening during the course of their antenatal care.   However, patients may present acutely to the emergency department with symptoms related to undiagnosed pre-eclampsia or complications of their pre-eclampsia. Therefore, it is important that doctors working in the emergency department have an understanding of the disease.

Approximately 1-2% of patients with pre-eclampsia will progress to eclampsia.  Although urgent obstetric review should be sought, it may be necessary to start emergency treatment of severe pre-eclampsia and eclampsia in the emergency department when patients present directly to the ED.

Learning bite 

Pre-eclampsia occurs in up to 6% of pregnancies. 


Pre-eclampsia is defined as:


  • New onset hypertension after 20 weeks of gestation (systolic blood pressure > 140 and/or diastolic blood pressure > 90)

And either


  • Proteinuria (urine protein:creatinine ratio ≥30mg/mmol)



  • Other features of pre-eclampsia1:
    • AKI (creatinine ≥ 90)
    • Liver dysfunction (ALT>40)/epigastric/RUQ pain
    • New severe persistent headache without an alternative diagnosis
    • Persistent visual disturbance 
    • Haematological complications (platelets <150/DIC/haemolysis)
    • Neurological complications (clonus/stroke/seizures(eclampsia))
    • Pulmonary oedema
    • Uteroplacental dysfunction (fetal growth restriction/placental abruption/intrauterine death)

Onset is usually after 20 weeks of gestation, but it can also occur up to a few weeks postpartum. 



  • This is pre-eclampsia that has progressed to cause seizure(s)

Learning bite

If new onset hypertension is associated with other features of pre-eclampsia, proteinuria does not necessarily need to be present. 

Classification of Hypertensive Disorders of Pregnancy

Hypertension known before pregnancy or present in the first 20 weeks Hypertension arising at or after 20 weeks (systolic ≥140 and/or diastolic ≥90)
 Chronic hypertension – essential  Chronic hypertension – secondary  White coat hypertension   Pre-eclampsia (de novo or superimposed on chronic hypertension) Gestational hypertension  

Gestational hypertension:

This is new onset hypertension in pregnancy but where there is an absence of significant proteinuria and any other features of pre-eclampsia.   Patients with gestational hypertension are at risk of going on to develop pre-eclampsia.

Chronic hypertension:

This may be previously diagnosed or recognised at the patient’s booking appointment.  These patients are also at risk of going on to develop pre-eclampsia.  

Learning bite 

Both chronic hypertension and gestational hypertension increase the risk of pre-eclampsia. 


  • Pre-eclampsia is a pregnancy-specific multi-system disorder with unpredictable, variable and widespread clinical manifestations
  • The pathophysiology is not clearly understood but the cause is thought to be multifactorial including genetic and immunological factors. 
  • It has been suggested that it originates in the placenta. It is thought to be associated with a failure of normal invasion of trophoblast cells, leading to maladaptation of maternal spiral arterioles (the source of blood supply to the fetus).  This would explain why it can result in placental insufficiency and fetal growth restriction. 
  • It has also been suggested that a systemic maternal response causes vasoconstriction and increased capillary permeability, leading to hypertension and the other complications associated with pre-eclampsia. 

Risk factors

There are multiple risk factors for pre-eclampsia2:


  • Primiparity (first pregnancy)
  • Previous pre-eclampsia
  • Family history pre-eclampsia
  • Obesity (risk increases with increasing BMI)
  • Extremes of maternal age (especially age > 40)
  • Multiple pregnancy (e.g. twins) 
  • Pre-existing hypertension
  • Pre-existing diabetes mellitus
  • Pre-existing vascular/renal disease
  • Autoimmune disease (e.g. SLE or anti-phospholipid syndrome)
  • Long interval between pregnancies (> 10 years)

Patients at risk of pre-eclampsia may be prescribed low dose aspirin from 12 weeks until delivery if they have a high-risk factor or more than 1 moderate risk factor for pre-eclampsia3:

High risk factor  Moderate risk factor 

Hypertension in previous pregnancy 

Chronic kidney disease

SLE/anti-phospholipid syndrome

T1DM or T2DM

Chronic hypertension


First pregnancy

Over 40 years old

Pregnancy interval more than 10 years

BMI over 35 at booking 

Family history of pre-eclampsia

Multiple pregnancy 

Learning bite 

Patients with hypertension in a previous pregnancy, chronic hypertension, chronic kidney disease, SLE/antiphospholipid syndrome, or diabetes mellitus are considered high risk of developing pre-eclampsia. 


Clinical features of pre-eclampsia:


  • Asymptomatic hypertension (picked up on screening or incidentally when presenting with another issue)
  • Headache (usually frontal)                                                                         
  • RUQ or epigastric pain (also a symptom of HELLP syndrome)
  • Nausea and vomiting
  • Oedema (common but not specific). Especially if rapidly increasing and involving face and hands.
  • Visual disturbance (flashing lights in the visual fields or scotomata)
  • Shortness of breath (uncommon but can occur due to pulmonary oedema)
  • Hyper-reflexia and/or clonus

Clinical features of eclampsia:


  • Tonic-clonic seizures
    • often in the setting of known pre-eclampsia 
    • can be at first presentation particularly if not engaged in antenatal care (only one third of women in the UK experiencing their first eclamptic seizure have established hypertension and proteinuria in the preceding week)

Learning bite

Many of the symptoms of pre-eclampsia are non-specific.  Pregnant patients presenting with headache or gastritis-like symptoms should have pre-eclampsia considered in the differential.

Crises in pre-eclampsia:


  • Acute kidney injury
  • HELLP syndrome
  • Placental abruption
  • Pulmonary oedema (may be sudden onset and catastrophic)
  • Transient left ventricular systolic or diastolic dysfunction
  • Eclampsia
  • Hepatic rupture
  • DIC
  • Haemorrhagic stroke
  • Cortical blindness

Clinical features of HELLP syndrome:

HELLP syndrome is a variant of severe pre-eclampsia characterised by haemolysis, elevated liver enzymes and low platelets.4   

Symptoms and signs are similar to those of pre-eclampsia but also include jaundice and bleeding.


  1. Haemolysis (H):
    • anaemia
    • dark urine
    • raised LDH (>600), raised bilirubin, schistocytes on blood film
  2. Elevated liver enzymes (EL):
    • Epigastric/RUQ pain/tenderness
    • raised transaminases
    • abnormal clotting (prolonged PT)
  3. Low platelets (LP):
    • Platelets < 100

Learning bite

HELLP syndrome is characterised by haemolysis, elevated liver enzymes and low platelets. 


It would not be appropriate for all the recommended investigations for pre-eclampsia to be carried out within the emergency department, however there are some simple bedside tests and blood tests that can help to diagnose pre-eclampsia and assess for complications.     Referral should be made to obstetrics for specialist management. 


  • Blood pressure monitoring – repeated measurement useful
  • Blood tests 
  • Full blood count (looking specifically at platelets)
  • Renal function (risk of AKI)
  • Liver function tests (risk of HELLP syndrome – haemolysis, elevated liver enzymes, low platelets) 

Also consider: 


  • blood film (risk of haemolysis and micro-angiopathic haemolytic anaemia) 
  • clotting screen (if thrombocytopaenic)


  • Urine
  • Urinalysis looking for protein (preferably use an automated reader as this is more accurate); 1+ or more of protein is significant.
  • If 1+ or more of protein is present on urinalysis, send urine for protein:creatinine ratio (≥30mg/mmol confirms proteinuria) or albumin creatinine ratio (>8mg/mmol significant)

After referral to obstetrics, further tests will be arranged to assess fetal wellbeing:


  • Cardiotocography (CTG)
  • Ultrasound (for fetal growth, umbilical artery doppler and amniotic fluid index)

Learning bite

Initial investigations in the ED for possible pre-eclampsia include blood pressure measurement, urinalysis and blood tests (FBC, U+E, and LFTs).


Recognition of Severe Features of Pre-eclampsia

Severe features of pre-eclampsia include severe hypertension with significant proteinuria or hypertension with other severe features of pre-eclampsia. 

Severe hypertension:


  • SBP ≥160 and/or DBP ≥110 (with significant proteinuria)

Other severe clinical features of pre-eclampsia3:


  • Ongoing or recurring severe headaches 
  • Visual scotomata 
  • Nausea or vomiting 
  • Epigastric pain 
  • Oliguria and severe hypertension 

Other features:


  • Abnormal blood tests (e.g. rising creatinine, transaminases or falling platelets)
  • Abnormal ultrasound (fetal growth restriction or abnormal umbilical artery doppler)

Learning bite

Severe pre-eclampsia is diagnosed when there is persistent hypertension above 160 systolic and/or 110 diastolic associated with significant proteinuria or other features of severe pre-eclampsia. Severe hypertension requires immediate antihypertensive treatment to reduce the risk of haemorrhagic stroke.


Differential Diagnosis

The differential diagnosis will differ depending on the presenting symptoms/signs.2

Presentation Differential diagnosis Differentiating features
Hypertension Chronic hypertension   Pre-existing hypertension, absence of new onset proteinuria
Gestational hypertension New onset hypertension, no proteinuria or other features of pre-eclampsia
Headaches/ visual disturbance  Anti-phospholipid syndrome Possible history of recurrent miscarriage/VTE/stroke/TIAs
 Thrombotic thrombocytopaenia purpura May have some/all of fever/confusion/low platelets/renal failure/haemolytic anaemia
Cerebral venous sinus thrombosis Absence of hypertension, progressive severe headache, neurological deficits 
Seizures  Epilepsy Previous diagnosis of epilepsy or previous seizure, absence of hypertension/proteinuria 
Thrombotic thrombocytopaenia purpura May have some/all of fever/confusion/low platelets/renal failure/haemolytic anaemia
Cerebral haemorrhage Patients with uncontrolled hypertension are at risk of cerebral haemorrhage. 
Abdominal pain/vomiting HELLP syndrome  May not have high BP or proteinuria. Haemolysis/thrombocytopaenia/ elevated liver transaminases
Acute fatty liver of pregnancy Part of pre-eclampsia spectrum. Differentiate from HELLP syndrome by hypoglycaemia which is a feature of AFLP but not HELLP.
Gallbladder disease Colicky, RUQ pain, normal BP/urinalysis. LFTs may show raised bilirubin/ALP, USS showing gallstones. 
Pancreatitis Previous history of pancreatitis/alcohol excess, normal BP, raised amylase/USS suggesting pancreatitis. 
Haemolytic uraemic syndrome  Bloody diarrhoea, microangiopathic haemolytic anaemia, low platelets/AKI

Learning bite

There is a wide differential diagnosis for pre-eclampsia that needs to be considered to prevent other serious diagnoses being missed.

ED Management of Pre-eclampsia:


  • Contact obstetrics early 
  • Manage the patient in an area with close monitoring if pre-eclampsia with severe features
  • BP management:
    • Labetalol first line unless unsuitable or contraindicated3 (e.g. asthma)
    • Nifedipine MR second line
    • Methyldopa third line (not used postpartum due to risk of depression)
  • Careful fluid balance monitoring
    • Fluid restriction to reduce the risk of pulmonary oedema
    • Monitor urine output if severe
  • Consider IV magnesium sulphate for eclampsia prophylaxis if severe features of pre-eclampsia

Definitive management:

Definitive management of pre-eclampsia is ultimately delivery of the fetus.   Timing of delivery will be decided by senior members of the obstetric team according to the severity of pre-eclampsia, the current gestation and in consultation with the patient. Following diagnosis of pre-eclampsia, the majority of women are managed as inpatients until delivery.

Learning bite 

For management of severe hypertension in pregnancy, follow local guidelines. An oral antihypertensive may be given initially (nifedipine MR 10mg or labetalol 200mg) followed by IV labetalol or IV hydralazine if adequate BP control is not achieved.1

ED Management of Eclampsia:


  • Ask for help early from ITU and obstetric teams
  • ABC approach, manage in left lateral position
  • Airway and breathing assessment with high flow oxygen 
  • If inadequate ventilation, consider early intubation (laryngeal oedema in pre-eclampsia and increased risk of aspiration in pregnancy)
  • Magnesium sulphate IV is treatment of choice for seizures – 4g loading dose over 5-10 mins then 1g/hr infusion for 24 hours
  • Further 2g boluses of magnesium sulphate can be given if further seizures occur after initial loading.3
  • Patients will need to be managed in HDU/ITU to stabilise blood pressure prior to delivery


If a patient is presumed to have eclampsia but is not responding to repeated boluses of magnesium sulphate, commence an anti-epileptic and consider alternative diagnoses. If not known to have epilepsy and no strong evidence that seizure is eclamptic, will need neuroimaging with CT head and/or MRV to look for other diagnoses including venous sinus thrombosis.

Learning bite 

Eclampsia should be considered in all women presenting with a seizure after 20 weeks’ gestation or in the postpartum period. Unless a seizure can be clearly attributed to epilepsy, magnesium sulphate should be commenced.  


  • Not considering pre-eclampsia or HELLP syndrome in the differential diagnosis due to non-specific presenting symptoms
  • Not recognising severe features of pre-eclampsia
  • Managing the pregnant patient with new seizures according to standard seizure treatment protocols rather than as suspected eclampsia
  • Not referring early to obstetrics for specialist management
  • Overlooking pre-eclampsia as a potential diagnosis when the onset is in the postpartum period


  1. Brown et al – 2018. Hypertensive Disorders of Pregnancy ISSHP Classification, Diagnosis, and Management Recommendations for International Practice. Hypertension, 72(1), pp.24-40.
  2. BMJ Best Practice Pre-eclampsia (updated 18/02/2020)
  3. National Institute for Clinical Excellence – Hypertension in pregnancy: diagnosis and management (NG133) (published 25/06/2019)
  4. BMJ Best Practice HELLP syndrome (updated 04/01/2019)

Additional resources

Impey, L. and Child, T., 2012. Obstetrics and Gynaecology, 4Th Edition. John Wiley & Sons, p.166.