GP management of pre-eclampsia

By Dr Louise Newson on the 16 August 2013

Dr Louise Newson identifies who is at risk of pre-eclampsia, what investigations are needed and management and prevention strategies.

Case study

Mrs GR is a 42-year-old primigravida who is now 38 weeks pregnant. She has had an uneventful pregnancy. She has a history of type 1 diabetes and is meticulous about her blood glucose control. She is not overweight and her BP has always been very well controlled, before she was pregnant and during the pregnancy.

She comes to see you in your surgery with worsening swelling of her ankles. She saw her midwife earlier in the week, who detected protein in her urine. Her BP at that time was normal. However, today in surgery you find that her BP is elevated at 162/102mmHg. You refer her to hospital urgently. You later find out that she did have pre-eclampsia; she was induced and gave birth to a healthy baby boy.

Pre-eclampsia is defined as pregnancy-induced hypertension (BP >140/90mmHg in the second half of pregnancy), in association with proteinuria (≥1+ proteinuria on reagent stick testing or >0.3g in 24 hours) with or without oedema.¹

Virtually any organ system may be affected; it can become life-threatening for the mother and her fetus.

Severe pre-eclampsia is defined as:

Diastolic BP of at least 110mmHg
Or systolic BP of at least 160mmHg
And/or symptoms
And/or biochemical impairment
And/or haematological impairment

Eclampsia is the occurrence of one or more convulsions superimposed on pre-eclampsia.

Pre-eclampsia can be associated with fetal growth restriction, low birthweight, preterm delivery, small for gestational age infants and respiratory distress syndrome.

Women who have had pre-eclampsia are at an increased risk of hypertension and heart disease in later life.²

Who is at risk?

The incidence of severe pre-eclampsia is about one in 200 pregnancies in the UK. Although severe pre-eclampsia and eclampsia are relatively rare, they are the second leading cause of direct maternal deaths in the UK.

The following women are at increased risk of pre-eclampsia:

First pregnancy or first pregnancy with a new partner
Pre-eclampsia or eclampsia in any previous pregnancy
10 years or more since last baby
Age 40 years or more
BMI 35 or more at presentation
Pre-eclampsia in mother or sister
Existing hypertension
Existing renal disease
Existing diabetes
Antiphospholipid antibodies

In addition to peripheral oedema, clinical features of severe pre- eclampsia may include headache, sudden swelling of face or hands, epigastric pain, vomiting, liver tenderness and/or visual disturbance.

Investigations

If proteinuria is present, urinalysis is usually undertaken for microscopy, culture and sensitivities. Frequent monitoring of FBC, LFTs, renal function, electrolytes and serum urate is undertaken to identify rising values and guide decisions about when to deliver the baby.

Clotting studies are only undertaken if there is severe pre-eclampsia or thrombocytopenia. A falling platelet count predicts severe disease and these women need urgent referral and further investigation.

Assessing the fetus involves ultrasound assessment of growth, volume of amniotic fluid and Doppler velocimetry of umbilical arteries.

HELLP syndrome

HELLP can occur in 10-20% of women with severe pre-eclampsia. This group of symptoms is characterised by haemolysis, elevated liver enzymes and low platelets. However, most cases of isolated thrombocytopenia in pregnancy are due to gestational thrombocytopenia, where the platelet count falls to 7-150 x 109/L, often late in the second or in the third trimester, rather than due to HELLP.

Management

Women with pre-eclampsia are usually managed in hospital with involvement of the obstetric team, anaesthetics, haematology and liaison with the paediatric team.

Appropriate arrangements for in utero transfer may be made if required and once the woman's condition is stable. However, many women can be managed conservatively if they are less than 34 weeks, haemodynamically stable, without coagulation abnormalities and in the absence of HELLP. Delivery of the fetus and the placenta is the only cure for pre-eclampsia.

Antihypertensive treatment should be started in women with a systolic BP >160mmHg or a diastolic BP >110mmHg. Labetalol (oral or IV), oral nifedipine or IV hydralazine are usually given for the acute management of severe hypertension.

Antihypertensive medication should be continued after delivery and in most cases can be reduced fairly quickly in the postpartum period.

In some women it may be necessary for up to three months.

Magnesium sulfate should be considered when there is concern about the risk of eclampsia.

Prevention

Antiplatelet agents, such as low-dose aspirin, have moderate benefits when used for prevention of pre-eclampsia. Many units now recommend aspirin in future pregnancies in women with a history of pre-eclampsia.

However, its use is still controversial.

One study has shown that low-dose aspirin has a small effect in prevention of pre-eclampsia in women considered to be at high risk of the disease, but it was not effective in reducing the risk in those at low risk.³

NICE recommends that more frequent BP measurements should be considered for pregnant women who have any risk factors for pre-eclampsia.⁴ Women should be admitted to hospital for further investigations if they have BP ≥160/100mmHg, raised BP with proteinuria or any clinical symptoms or signs of pre-eclampsia.