ANTENATAL URINE TESTING FOR PRE-ECLAMPSIA
Action on Pre-eclampsia here presents its recommendations on testing urine in pregnancy to screen for pre-eclampsia. These suggestions, developed in consultation with experts, represent the Charity’s idea of good practice.

Summary

Action on Pre-eclampsia believes that all pregnant women should have their urine dipstick tested for protein at every routine antenatal visit, whether in a hospital, community or domiciliary setting. Trace results may be ignored, but new readings of ‘+’ or more from 20 weeks onwards should be seen as a sign of potential pre-eclampsia, even in the absence of other diagnostic signs.

Positive readings should be confirmed by a formal biochemical measurement of the protein content of a 24-hour collection. A urinary infection, very occasionally, causes transient proteinuria and can be excluded by appropriate laboratory investigation. However, decisions about management should not be delayed pending investigation but based on the assumption that infection is not the cause. A woman who has confirmed protein in her urine and other diagnostic signs (especially increased blood pressure – even if only moderate in degree) has pre-eclampsia. Under ideal circumstances, she will benefit from immediate, continuous hospital-based monitoring, which would be mandatory if she also has symptoms of fulminating pre-eclampsia, such as atypical headache, visual disturbances or epigastric pain. Even if proteinuria is the only abnormality detected, the woman should be monitored more frequently and intensively than before on an outpatient basis.

Background

High blood pressure (hypertension) and loss of protein in the urine (proteinuria) are the two main diagnostic signs of the common and potentially dangerous pregnancy complication pre-eclampsia. For practical purposes, the threshold for increased vigilance is a maternal blood pressure > 140/90 mmHg and/or protein loss > 0.3g per 24 hours. Because pre-eclampsia is symptomless in its early stages, detection depends on mass screening of apparently well women. For optimum detection it is necessary to screen for these signs at every antenatal appointment throughout the pregnancy. Nevertheless, official survey evidence suggests that urine testing is carried out less rigorously than blood pressure checks (1). APEC’s own survey and anecdotal evidence suggest first, that women are less likely to have their urine than their blood pressure checked at every visit and second, that proteinuria is less likely to be taken seriously than hypertension, especially at early gestations and in the absence of confirmatory signs (2).

Testing guidelines

We offer the following recommendations for effective urine testing.

Routine testing

Stepped-up monitoring and referral

Testing after admission

Testing after delivery

References
(1) Audit Commission Maternity Study, 1997
(2) APEC membership survey, 1998

Signs and symptoms of pre-eclampsia

This section has been designed to be a printable guide to the detection, diagnosis and management of pre-eclampsia for GPs, midwives and others involved in the care of pregnant and recently pregnant women.

Pre-eclampsia is the most dangerous of the common complications of pregnancy, a leading cause of maternal death and a major contributor to perinatal mortality. But the condition is poorly understood at a clinical level, while many pregnant women have never even heard of it.

Substandard care at all levels still occurs, compounding the risk to mothers and babies.

Pre-eclampsia can be difficult to detect and diagnose because:

Yet early detection is crucial to the prevention of perinatal and even maternal death, since pre-eclampsia can evolve to a life-threatening crisis in a few hours.

What is pre-eclampsia?

Fundamentally, pre-eclampsia is a placental disorder caused by partial failure of the blood supply to the placenta. The resultant ischaemia has knock-on effects for both mother and baby. The baby may suffer growth restriction and, later, fetal distress which can lead to intrauterine death.

The mother's problems are signalled first by a generalised circulatory disorder, usually manifested by hypertension and/or proteinuria with or without oedema. This can lead to such complications as:

Pre-eclampsia cannot be reliably predicted or prevented, and the only cure is delivery.

The variability trap

The maternal illness varies widely in its presentation. To make the diagnosis, at least two typical features need to be present, normally new hypertension combined with new proteinuria (at least + on dipstick testing).

However, there are other combinations of features which may not include one of these signs - it is important to recognise this variability and to think about the possibility of severe pre-eclampsia even with minimal or no hypertension, or no proteinuria.

Always....

Never....

The scale of the problem

Pre-eclampsia affects 1 in 10 pregnancies overall and as many as one in five first pregnancies. Most cases are mild, but one first pregnancy in 100 is so severely affected that there is serious risk to the life of the baby - and even the mother.

Pre-eclampsia causes the deaths of an estimated 1,000 babies in the UK every year - many dying as a consequence of extreme prematurity. And it remains a leading direct cause of maternal death, killing 7-10 mothers per year.

As many as nine out of 10 maternal deaths from pre-eclampsia are associated with substandard care.

Who is at risk?

Women with any one of the following factors:

• 1st pregnancy
• 10 years or more since last baby
• 40 or more years of age
• BMI of 35 or more at booking
• A family history of pre-eclampsia (mother, sister)
• Booking diastolic BP 80-89 mmHg
  

Signs and what they tell you

Pre-eclampsia can develop at any time after 20 weeks of pregnancy, but is most common in the third trimester. It may reveal itself first by any one - or more - of the following signs:

Raised blood pressure that fails to settle on a second check:

Raised blood pressure that settles completely on a second check:

Look for other signs of pre-eclampsia. If found, assume the diagnosis of pre-eclampsia and seek a hospital assessment within a few days. If signs are not found, increase the frequency of antenatal checks as a precaution. If blood pressure remains settled and no other signs of pre-eclampsia emerge, a more standard approach to care can be slowly resumed.

Stepped-up monitoring and referral

Arrange more frequent visits for routine checking if there is:

Refer to hospital on the same day if there is:

Arrange emergency admission if there is:

Screen according to risk

The standard pattern of antenatal checks - monthly to 23 weeks, fortnightly to 36 weeks and weekly to term.

Although the level of the blood pressure usually mirrors the severity of the disease, severe pre-eclampsia can be associated with mild hypertension or, rarely, with normal blood pressure.

Oedema - Ankle oedema occurs in a high proportion of normal pregnancies, but the oedema of pre-eclampsia tends to be associated with rapid weight gain and to involve the face and hands.

Regular weight checks are no longer recommended in pregnancy. Nevertheless there is some evidence that rapid weight gain (more than 1kg per week over two or three weeks) is an important predictor of pre-eclampsia.

Proteinuria - New proteinuria (at least +) in a mid-stream sample of urine usually appears after hypertension, but it can precede it and be an important predictor of problems. New proteinuria combined with new hypertension indicates more advanced disease and is an indication for same-day referral to hospital. Proteinuria is such an important sign that no antenatal check-up is complete without testing the urine.

Growth restriction - Sometimes pre-eclampsia affects the unborn baby before the mother, when growth restriction can be the first sign. If manual examination suggests poor growth, the mother should be referred to hospital for assessment.

The detection of any one of these signs is an indication for more intensive monitoring. At least two must be present before pre-eclampsia can be diagnosed.

Symptoms to take seriously

Most cases of pre-eclampsia are detected at antenatal check ups when the disease is pre-symptomatic. However, some cases - particularly those of early onset - present symptomatically between checks. Symptoms women may report include:

Women with these symptoms should be seen urgently by a doctor and checked for signs of pre-eclampsia. If the diagnosis is confirmed or suspected (as with epigastric pain with hepatic tenderness) urgent admission to hospital is vital because a crisis may be imminent.

Play safe with epigastric pain

This is a grave and often misdiagnosed symptom of fulminating pre-eclampsia, which should always be investigated thoroughly. It may be confused with gastroenteritis, heartburn and even acute cholecystitis particularly when, as sometimes happens, there are no other signs of pre-eclampsia.

What distinguishes pre-eclamptic epigastric pain from heartburn is hepatic tenderness. Unlike heartburn, it is not burning in quality, does not spread upwards towards the throat, may radiate through to the back and is not relieved by antacid.
.
It is often very severe - described by sufferers as the worst pain they have ever experienced.

Tell women what to look for

Since pregnant women may not appreciate the potential significance of the symptoms described here, they should be advised to take heed of any possible indicators - including general malaise, and to arrange to be seen promptly by their midwife or doctor.

Unheralded eclampsia

In some cases, pre-eclampsia evolves to a crisis unheralded by conventional diagnostic signs. It is known, for example, that eclampsia can occur in the absence of both hypertension and proteinuria, although these signs invariably appear after the fits. Therefore, all cases of unexpected convulsions in pregnant women should be assumed to be eclamptic.

In cases of presumed eclampsia ...

... Protect the airway and await spontaneous recovery. Intravenous diazepam can be used to prevent or treat recurrent convulsions. Arrange emergency admission to hospital by ambulance, and accompany the patient.