Dr Sue Page
Aboriginal Health
Women's Health
Antenatal Diagnosis of Congenital Abnormality
Emotional aspects of menopause
Endoscopic Surgery in Gynaecology
Obstetric Emergencies - Antepartum
Obstetric Emergencies - Intrapartum
Obstetric Emergenies - Postpartum
Preventable Causes of Congenital Abnormalities
The Principles of Antenatal Care
Table of Contents
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Most complications of pregnancy allow time for transfer to specialized 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 dept. than the maternity ward.
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.
calcium intake in excess of 2000mg daily is associated with a
reduced risk of developing HT in pregnancy, insufficient evidence to
support improved outcome as a result
no proven benefit in salt reduction or water restriction
2 controlled trials, with conflicting results
reduce the risk of hospital readmission and emergency delivery.
methyldopa is the most widely used, onset 4 hrs. clonidine works
similarly, but within 30 mins
beta-blockers reduce cardiac output, and may slightly increase
the risk of IUGR
randomised trials of calcium channel blockers are so far too small
to give useful estimates of their effects, as are studies of
prostaglandin precursers.
direct comparisons (nifedipine vs hydralazine, labetalol vs
hydralazine, labetalol vs diazoxide, and prostacyclin vs
dihydralazine) fail to show a clear preference.
diazoxide may cause a rapid drop in arterial pressures & fetal
hyperglycaemia, labetalol may cause fetal bradycardia
phenytoin is only recommended for prevention of convulsions, so
used in conjunction with diazepam if required. most established
infusion protocols rely on dose/weight, impractical in the acute
setting. requires cardiac monitoring.
magnesium first used in 1906 (intrathecally), the drug of choice
in the USA (Consensus 1990). It can cause cardio-respiratory arrest,
so close monitoring is needed, including serology, with calcium
readily available as an antidote. Wide safety margin, cheap, with
rapid onset. The Collaborative Eclampsia Trial (Lancet 1995), and
Lucas et al (NEJM 1995) have compared MgSO4 to diazepam and/or
phenytoin, and found significantly lower risks of recurrant seizures
(52% < diazepam,67%< phenytoin group) with a significantly
lower risk of needing ICU +/- intubation, of developing pneumonia, or
of infants needing SCU +/- intubation.
Antepartum haemorrhage
APH is bleeding after 20 weeks, until the birth of the baby, and
occurs in 3%of all pregnancies.
Placentas which 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:
PET & eclampsia
Around the world, each year approx. one half 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 approx. 10% of maternal deaths (Duley 1992), or 50 000
maternal deaths per year.
Definition & Incidence
Pre-eclamptic Toxaemia (PET) is defined as any two of three
criteria:
PET will occur in 6% of first and 2% of subsequent pregnancies, esp.
if family history of PET, HT, or auto-immune disease. Risk also
increased if multiple, large, or abnormal infants, maternal diabetes,
or poor nutritional state of mother.
PET requires admission to an obstetric unit for close monitoring of
mother and infant. The condition will often improve with bedrest, but
if severe, and eclampsia seems imminent, urgent delivery is warranted
regardless of gestation.
Eclampsia is fitting during or shortly after pregnancy. It may
progress to status epilepticus, with cerebral oedema or haemorrhage,
pulmonary oedema, cardiac failure, aspiration pneumonitis, liver and
renal failure, and DIC. It is vital to realise that Eclampsia can
occur without preceding signs, but that it is often preceded by:
Prophylaxis:
Diuretics
12 randomised trials, 7000 women no clear evidence of benefit in
progression of PET or perinatal death, no serious side effects
reported
Antithrombotic and antiplatelet agents
studies of asprin +/- dipyridamole are encouraging, but at this
time do not substantially improve outcomes. Heparin is inconvenient,
and increases bleeding complications, for no proven benefit
Dietary Measures
no evidence to support protein or calorie modification benefit
Treatment of mild/mod. PET or HT
Bed rest
socially costly and usually stressful, may be financially costly
Elective confinement
1 small trial suggesting the outcomes for the mother are improved,
but are worsened for the infant. No clear guidelines reached,
although generally accepted to deliver at term.
Antihypertensives
clearly reduce blood pressure, no effect on oedema or proteinuria,
may slightly reduce risk of neonatal death.
Treatment of severe PET/Toxaemia
Antihypertensives
hydrallazine most commonly used, then beta-blockers, and
diazoxide less often.
Plasma volume expanders
non-crystalloid solutions (eg. dextran, albumin) have been used to
restore the circulating plasma volume of severe PET. Uncontrolled
trials suggest by doing so, other drug doses can be minimised,
reducing side-effects. Insufficient data to reliably exclude an
increased risk of cerebral or pulmonary oedema as a consequence.
Anti-convulsants
librium and diazepam have been used since 1960's. cheap, and
readily available but are slowly metabolised by the infant, and
apnoeas, hypotonia, poor sucking may last days. rate of infusion is
titrated to maternal level of consciousness, so difficult to nurse.
Motor vehicle accidents
Injuries are less severe if seat belts are worn, but are then
usually lower abdominal trauma. Abruption can occur several hours
after the impact, so if high speed MVA consider admitting for 48
hours fetal monitoring.
Diabetic coma
Ketoacidotic coma is rare in pregnancy and fetal outcome very
poor. Hypoglycaemic collapse is more common and usually causes little
fetal impact as insulin does not cross the placenta. Treat with IV or
IM glucagon.
Sue
Page,cmitchel@om.com.au
General Practioner
Lennox Head
NSW
Australia 2477
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