Obstetric emergencies

Most complications of pregnancy allow time for transfer to specialised obstetric units, but a few women present as emergencies where successful outcome depends on prompt recognition of the problem and rapid stabilising management. It is not uncommon for staff with no formal obstetric training to be facing these situations in the A&E or general practice setting.

The golden rules of obstetric emergencies

(1) Apply oxygen with the woman rolled into the left lateral position (by at least a bag of IV fluid under the right hip) even if the woman is unconscious and being intubated. Compression of the vena cava/aorto-iliacs by the gravid uterus reduces venus return, resulting in hypotension and reduced blood flow to the fetus; and increases lower abdomen venous pressure which may be transmitted to the retro-placental space, increasing the risk of placental separation and haemorrhage.

(2) In general, it is best to concentrate on the resuscitation and transfer of the mother, as the infant is safer in utero. Fetal hemoglobin oxygen-binding-capacity maintains adequate oxygenation until maternal partial pressures are < 60, contrasting starkly to the difficulties in ventilating an infant with premature lungs.

(3) In the young and healthy, tachecardia and hypotension are very late features of shock and need to be considered extremely seriously.

(4) Be alert that the emergency may (uncommonly) not be due to the pregnancy, as this may alter management. For example, a pregnant woman with palpitations and collapse may have PAT or cardiomyopathy and be better treated in the A&E department than the maternity ward.

Antepartum haemorrhage

APH is bleeding after 20 weeks, until the birth of the baby, and occurs in 3% of all pregnancies.

Placentas that are low lying (praevia) are usually detected by ultrasound and the women aware they may, as a consequence, have painless spotting or heavier bleeding, especially if they have intercourse after 32 weeks.

Abruption placental separation will more commonly present as an emergency. The blood loss may be revealed or concealed, usually both, and is easily underestimated. Pain is intense and constant, and the uterus large and rigid. Abruption is more common if high parity, poor nutrition, hypertension, or toxaemia.

Management involves:

Quickly assess, with oxygen and lateral positioning, and fetal heart rate.

Large bore IV access, with blood collected for group and crossmatch to be transferred with the patient.

Replace estimated losses plus 2 litres IV fluid.

Consider catheterisation to monitor output, and because a full bladder can contribute to uterine relaxation and further bleeding.

Arrange escorted transfer to obstetric unit for further assessment even if bleeding seems to settle, as the fetus may be compromised.

Anti-D may be required.

PET & eclampsia

Around the world, each year about half a million women die of pregnancy related causes. 99% of these occur in the developing world, usually of infection or haemorrhage, but in the developed countries, HT is the major preventable cause of fetal and maternal morbidity and mortality, affecting up to 5% of pregnancies. Worldwide, toxaemia accounts for about 10% of maternal deaths (Duley 1992), or 50 000 maternal deaths per year.

During pregnancy, generalised vasodilation and the large area of low-resistance shunt in the placental bed, result in increased cardiac output (40%) due to increased stroke volume. There are also increases in extracellular and blood volumes, renal blood flow, and glomerular filtration rate (50% at 16 weeks), and changes in renal tubular function. These are thought to be due to the effects of circulating prostaglandins. The net effect is a 10% decrease in BP in the first half of the pregnancy, with a gradual return to normal values by term. During labour, and continuing for a few days, BP can rise acutely due to increased preload with contractions, and pain and fear, with up to 12% of otherwise normal women having diastolic pressures exceeding 100mmHg. Also, 50 - 80% normotensive women are reported to have oedema at term.