Pre-eclampsia is part of a spectrum of conditions known as the hypertensive disorders of pregnancy. Its exact pathophysiology is uncertain.

Pre-eclampsia is part of a spectrum of conditions known as the hypertensive disorders of pregnancy.

Its exact pathophysiology is uncertain.

It is diagnosed when there is hypertension and proteinuria that develop after 20 weeks of gestation.

It is best considered as a multisystem disorder as a range of other important associated complications may also be seen. 

Pre-eclampsia is the commonest medical complication of pregnancy and is associated with substantial morbidity and mortality for both mother and baby.

Although outcome is usually good with proper management, pre-eclampsia can be a devastating and life threatening condition for both mother and baby.

The most severe manifestation of pre-eclampsia is eclampsia, which is characterised by the onset of seizures.

Patients who present with severe preeclampsia must be very closely monitored for impending eclampsia.

The most important initial therapy in severe pre-eclampsia is magnesium sulphate.

The only definitive cure is delivery.

See also document separate documents for:

●          Eclampsia (in O&G folder).

●          HELLP Syndrome (in O&G folder).

Classification of Hypertensive Disorders of Pregnancy

1.         Chronic hypertension:

●          Hypertension that predates the pregnancy or arises prior to 20 weeks of      gestation.

2.         Gestational hypertension:

●          Onset of hypertension after 20 weeks gestation, but without any maternal   or fetal features of preeclampsia, (there is no proteinuria) and a return to           normal blood pressure within 3 months of delivery.

Note that the circulatory volume is normal in contrast to the situation in preeclampsia where it is contracted.

●          Hypertension defined as systolic blood pressure ≥ 140 mm Hg or diastolic blood pressure ≥ 90 mm Hg

3.         Preeclampsia /eclampsia:

●          Onset of hypertension after 20 weeks gestation, together with other            features of end organ dysfunction.

                        The hypertension resolves within 6 weeks of delivery.

4.         Preeclampsia superimposed on chronic hypertension:

●          The development of end organ dysfunction after 20 weeks gestation in       women with chronic hypertension.  


The syndrome poses a threat to both mother and fetus.

Current theories suggest that PET/eclampsia is a placental disorder, resulting in a widespread endothelial dysfunction and coagulopathy.

●          There is a generalized vasospasm resulting in hypertension and organ damage due             to hypoxia, especially of the brain, liver and kidneys.

●          There is a widespread increase in vascular permeability resulting in “third space” losses. There is a loss of albumin in the urine reducing intravascular osmotic pressures. The result is peripheral edema in association with a “contracted”          intravascular volume.

●          The coagulopathy primarily manifests as a severe DIC or the HELLP syndrome.

Predisposing Clinical Factors:

These include:

1.         Age:

            ●          > 40 years of age.

2.         Obstetric history:

            ●          Pre-eclampsia in a previous pregnancy

            ●          Previous gestational hypertension.

            ●          Multiple pregnancy.

            ●          Primagravidas more common in multigravidas.

3.         Preexisting conditions:

            ●          Chronic hypertension

            ●          Chronic renal disease

            ●          Diabetes

            ●          Presence of antiphospholipid antibodies or other thrombophilias

            ●          Some congenital heart conditions.

            ●          Obesity (Body mass index  ≥  35) at booking in.

4.         Family history


The disease process most commonly progresses from a “pre-clinical” stage, through a symptomless clinical stage (hypertension, edema, proteinuria, but without symptoms) to a clinical stage with symptoms.

The clinical stage with symptoms (“imminent” preeclampsia) may lead to a number of possible clinical crises as listed below:

1.         Eclampsia:

●          This is the encephalopathic complications of altered conscious state and     seizures.

2.         Hypertensive emergencies:

            ●          Such as SAH or intracerebral hemorrhage.

3.         Hepatic:

            ●          This may range from mild impairment to fulminant failure.

4.         Renal:

            ●          Acute renal impairment / failure

            ●          Oliguria

5.         Hematological:

            ●          DIC

            ●          HELLP syndrome:

                        ♥          “H” Hemolysis, “E” Elevated liver enzymes, “LP” Low platelets

            ●          Haemolysis

6.         Respiratory:

            ●          Acute pulmonary edema

7.         Fetal crisis:

            ●          Placental abruptions or infarctions.

            ●          Growth retardation.

            ●          FDIU

Rarely a clinical crises may occur without preceding clinical signs of PET, sudden onset of seizures for example.

However, within 24 hours the typical signs of edema, hypertension and proteinuria are seen.

Clinical Features

All pregnant women should have regular assessment of their blood pressure and urinary analysis for proteinuria.

These checks should be routine minimums for any pregnant woman who presents to the ED

Establishing the diagnosis:

Pre-eclampsia is diagnosed when there is hypertension and proteinuria that develops after 20 weeks of gestation.

Hypertension defined as:

●          Systolic blood pressure ≥ 140 mm Hg


●          Diastolic blood pressure ≥ 90 mm Hg

Proteinuria defined as:

●          ≥ 1+ on dipstick screening


●          ≥ 300 mg/day, (a more sensitive indicator)


●          A ratio of protein to creatinine >30 mg/mmol. 2

Generalized edema:

●          Note that edema is no longer included in the diagnostic features of pre-eclampsia.

            It occurs equally in normal pregnancy and those with pre-eclampsia.

            The rapid development of generalized edema however may be abnormal.

●          Note that ankle edema especially at the end of the day in pregnancy is normal.

            Morning ankle edema and edema of the hands and face are more suggestive features of abnormal edema.

Assessing the degree of severity:

As a rough guide severity may be assessed according to the following:

  Severity    Blood Pressure  Proteinuria  Symptoms  Biochemistry
  Mild    140/90  None  None  Normal
  Moderate    150/ 95  (+1)  None  Normal  
  Severe    160/110   (+2)  Maybe present  Abnormal  
  Imminent    160/110  (+3)  Present  Abnormal

The features of severe or “imminent” eclampsia include:

●          Clinical signs of preeclampsia:

♥          Hypertension, proteinuria, severe swelling of hands, face, or feet of            sudden onset.

in addition to:

●          Symptoms


●          Laboratory abnormalities, (see Investigations below).

Symptoms may include:

1.         Neurological:

●          Headache.

●          Drowsiness

●          Hyperactive reflexes and / or clonus.

These neurological findings are precursors of convulsions, i.e. eclampsia, and

require consideration of magnesium sulfate therapy and urgent delivery

2.         Visual disturbances:

●          Blurred vision or diplopia

●          Visual scotomata

These may signifying occipital cortical ischemia.

3.         Hepatic dysfunction:

●          RUQ abdominal pain and tenderness.

Eclampsia (or other crises) on occasions may occur suddenly without preceding clinical signs and symptoms of preeclampsia.

Preeclampsia (especially if symptomatic) may progress rapidly to fulminating complications and eclampsia.

Preeclampsia is an inevitably progressive process. The rapidity of progression of   signs and  symptoms is also important in addition to absolute values.

Differential diagnoses:

These will essentially be those of the hypertensive disorders of pregnancy listed above.


When preeclampsia is suspected the following investigations will be needed:

Blood tests:

1.         FBE:

●          Look in particular for thrombocytopenia, (platelets <1 00 x 109/L)  which can be an early sign of DIC.

2.         U&Es and glucose:

●          For renal impairment/ failure.

●          Serum/plasma creatinine ≥ 0.09 mmol/L is significant.

3.         LFTs:

●          A rise in liver enzymes, especially aspartate aminotransferase (AST) to at least twice normal indicates hepatic cellular damage.

            ●          Bilirubin may be raised secondary to hemolysis.

4.         Coagulation profile:

●          INR, APPT

●          Decreased fibrinogen and increased FDPs

5.         Serum uric acid:

●          Uric acid clearance falls in pre-eclampsia, and there is a consequent rise in serum levels. A value exceeding 0.35 mmol/L is abnormal.


FWT (note that protein may also be due to infection or contamination)

MSU for M&C, (to rule out infection)

Macroscopic haematuria and/or casts on microscopy suggest an underlying renal parenchymal disease.


To monitor fetal well-being.

Severe/Imminent PET is diagnosed when there are symptoms and/or laboratory abnormalities. Intrauterine growth restriction is also a significant finding.


1.         General nursing:

            ●          Monitor vital signs closely

            ●          Nurse in a calm and quite environment

            ●          Nurse in the left lateral position

            ●          Commence a strict fluid balance chart

            ●          Establish IV access.

2.         Establish monitoring:

The exact degree of monitoring required will be determined by how unwell the patient is.

            The following should be considered:

●          IDC, (monitor for oliguria, a urine output of at least 0.5 mls/kg/hr is           desirable)

●          Blood pressure (non invasive/ arterial line)

●          ECG

●          Pulse oximeter

            ●          CTG monitoring

3.         Oral antihypertensive drugs: 1

●          Oral antihypertensive drugs are mandatory for systolic blood pressure ≥     170 mm Hg or diastolic pressure ≥ 110 mm Hg, although lower thresholds are advisable if signs or symptoms are present.

Options include:

●          Labetolol

●          Methyldopa

●          Nifedipine SR

Severe or imminent cases will require more aggressive treatment:

4.         Magnesium sulphate:

●          There is now good evidence that, for women with severe pre-eclampsia,     magnesium sulphate more than halves the risk of progression to eclampsia           and probably reduces the risk of maternal death as well

            ●          Magnesium sulphate is the drug of choice for treating eclamptic fits.

            ●          It should generally precede any antihypertensive therapy.

            See Eclampsia Document for dosing details.

            Note that prophylactic phenytoin is not recommended.

5.         Parenteral antihypertensives:

There are two main options:

●          IV labetalol:

♥          Intravenous labetalol is now considered to be the primary drug            of choice for the urgent control of severe hypertension in          pregnancy.

●          IV hydralazine:

♥          Traditionally used in the past, but in fact is classified as a class C    drug in pregnancy.

♥          Hydralazine may still be considered for women with a         contraindication to IV beta blockers such as a history of   significant asthma or congestive heart failure. 2

See eclampsia document for further dosing details.

6.         Delivery:

The only definitive “cure” for pre-eclampsia is to deliver the placenta.

Delivery is generally indicated in severe pre-eclampsia or in a fetus of greater than 37 weeks gestation.

Decisions about the exact timing on this as well as the mode of delivery (i.e. induced labour or caesarean section) can be complex, and are assessed on a case by case basis by the treating Obstetric Unit.

Factors that come into consideration will include

●          The well being of the mother

●          The well being of the baby

●          The maturity of the baby

●          The informed wishes of the mother

It should be noted however that the risks of pre-eclampsia do not resolve immediately upon delivery and that in fact both pre-eclampsia and eclampsia can occasionally present for the first time after the birth.

As a general rule most women will show signs of recovery within the first 24 hours of delivery.

            Syntocinon may be used, but ergometrine should not be used.


Any woman who presents to the ED with preeclampsia must be discussed with the Obstetric Unit.

Those with moderate to severe preeclampsia are admitted to hospital. Mild cases may also be admitted depending on individual associated factors.

Patients with severe preeclampsia must be monitored, and admission should be to a High Dependency Unit, or Birthing Suite where this can occur.

After a pregnancy complicated by pre-eclampsia, women should be advised of the risk of

recurrence and assessed for chronic hypertension and other underlying conditions

Women who have had pre-eclampsia are at increased risk of developing it again in subsequent pregnancies and need to be advised of this.




Fellowship Notes

Dr Jessica Hiller LITFL Author

Doctor at Sir Charles Gairdner Hospital in Western Australia. Graduated from Curtin University in 2023 with a Bachelor of Medicine, Bachelor of Surgery. I am passionate about Obstetrics and Gynaecology, with a special interest in rural health care.

Dr Lucy J Yarwood LITFL author

MSc, MBChB University of Manchester. Currently doctoring in sunny Western Australia, aspiring obstetrician and gynaecologist

Physician in training. German translator and lover of medical history.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.