Professor Jeffcoate’s 1996 observation that ‘The only certain means of cure…[for preeclampsia]…so far known is removal of the pregnancy’ holds today.¹ However, achieving delivery in severe preeclampsia also puts a sick woman and her fetus through a stress test, irrespective of route, timing, analgesia or anaesthesia.

Blood pressure may rise with Valsalva manoeuvres during expulsive second stage of labour or during intubation for general anaesthesia. Myocardial work increases during labour and particularly in the hour after birth. Bleeding diatheses make neuraxial blockade hazardous and can increase postpartum blood loss. Pharyngeal oedema increases the difficulty of intubation.

Maternal death and ‘near miss’ in severe preeclampsia

Preeclampsia kills mothers, being within the top-three causes of maternal mortality in developed countries such as Australia and New Zealand. British and Dutch enquiries identified substandard care in 70 to 95 per cent of such cases.² There is therefore further scope to reduce maternal mortality where preeclampsia threatens life or organ function or contributes to the morbidity of associated placental abruption, disseminated intravascular coagulation or anaesthetic complications.

Life- or organ-threatening complications in preeclamptic toxaemia (PET) include eclampsia; cortical blindness; stroke; massive transfusion; inotrope requirement; myocardial infarction; temporary or permanent renal replacement; hepatic rupture; failure or haematoma; or intensive care respiratory support. Such severe morbidity occurs about ten to 100-fold more commonly than death: compare US late 20th century case fatality for preeclampsia/eclampsia of 6.4/10,000³ with early 21st century Canadian data on severe complications in preeclampsia/eclampsia of up to 5.1 per cent.⁴

Principals of peripartum management of severe preeclampsia

The principals of avoiding maternal death and near-death events include the following:

Recognise severe preeclampsia

• Expect the unexpected in that even mild PET may fulminate.⁵
• Do not be lulled into a false sense of security if treatments such as MgSO₄, anti-hypertensives and/or steroids appear to have stabilised the condition. Remember that the placental abnormality has been present from first trimester and the maternal response abnormality may also have been present soon after abnormal placentation.^2,6
• Recognise any organ dysfunction² but pay special attention to:
  • SBP of 160 mmHg or higher:
    • This is lower than previously popular reportable limit 170 mmHg but is based on robust associations with maternal risk.^2,5,7 
  • Early gestation:
    • especially less than 32 weeks which confers a 20-fold increase in maternal mortality, let alone perinatal mortality.³
  • Maternal symptoms
    • the patient may tell us more than her test results.^2,8

Stabilise and deliver

• Stabilise blood pressure
  • Aim to reduce blood pressure to 140-150/90-100 mmHg at a rate of 10-20 mmHg every ten to 20 minutes⁷:
    • avoiding excessive systolic hypertension
    • avoiding excess diastolic hypertension
    • avoiding precipitate fall in blood pressure.
  • Usually parenteral agents are required peripartum due to unreliable enteral absorption of medication. Choices include:
    • IV hydralazine as bolus and/or infusion
    • IV labetalol as bolus and/or infusion
    • IV mini-dose diazoxide.⁹
• Manage fluids
  • Both acute pulmonary oedema (APO) and pre-renal renal failure may occur, but APO has greater lethality.
• Prevent and treat eclampsia
  • 85 to 90 per cent of eclampsia occurs within 48 hours of birth
    • ten to 15 per cent occurs later than this (but is not the subject of this review)
  • MgSO₄ has best evidence of efficacy and safety for both treatment and prevention of eclampsia^10-14
  • MgSO₄ may act by some, all or other mechanisms than the following six postulated below:
    • vasodilatation of the cerebral vasculature
    • inhibition of platelet aggregation
    • protection of endothelial cells from damage by free radicals
    • prevention of Ca2+ entry into ischaemic cells
    • decreasing the release of acetylcholine at motor end plates within the neuromuscular junction
    • a competitive antagonist to the glutamate N-methyl-D-aspartate receptor (which is epileptogenic).

Optimise team work

To stabilise and deliver requires a team of people, not just the erudite individual reading this article. Optimal management of PET requires multidisciplinary care: obstetric, midwifery, anaesthetic, pathology and paediatrics. Team members will have varying levels of experience, academic aptitude and personality-based responses when facing an emergency such as preeclampsia. Clinical practice guidelines and drills can improve team work in maternity care. ‘Enquiries into suboptimal outcomes have identified common errors: confusion in roles and responsibilities, lack of cross-monitoring, failure to prioritise and perform clinical tasks in a structured coordinated manner, poor communication and lack of organisational support. As a consequence, there has been a shift away from individual responsibility towards improved team working’.¹⁵

Clinical practice guidelines

Precise yet comprehensive clinical practice guidelines accessible to all members of the team appear to improve patient safety in preeclampsia.^2,4 It is reasonable to adapt published guidelines for local circumstances (for example, www.rcog.org.uk/en/guidelines-research-services/guidelines/gtg10a/ or www.anzca.edu.au/fellows/sig/obstetric-anaesthesia-sig/obstetric-anaesthesia-scientific-evidence [link expired; please search www.anzca.edu.au]).

An intellectually vibrant, articulate, dextrous, charismatic consultant obstetrician will reliably extract optimal performance from his or her team of junior obstetric staff, midwifery, anaesthetic or pathology staff, the patient and her family, thereby saving mother and baby from death and disaster and earning at least one box of chocolates, if not a standing ovation and request for an encore. He or she does not need a clinical practice guideline to cramp their (operatic) style. The rest of us, though, are helped by a clinical practice guideline so everyone is singing from the same songsheet. With a good clinical practice guideline, even a day-one graduate midwife or day-one resident doctor can reliably identify a new case of preeclampsia, obtain intravenous access, order reasonably appropriate blood and urine tests, commence a cardiotocogram and notify senior obstetric and anaesthetic staff. This will happen most of the time irrespective of whether or not the less-than-charismatic obstetrician is giving the case the full attention of a teaching ward round, is asleep in bed or occupied elsewhere.

Drills

Drills appear to improve patient outcomes in many obstetric emergencies.¹⁶ Eclampsia is particularly suitable for hospital-based, multidisciplinary drills:

• Eclamspia is rare and frightening, so the safety of drills is usually welcomed by doctors and midwives.
• A readily measurable outcome such as time to administer a loading dose of MgSO₄ tests team efficiency. Teams that are efficient in delivering MgSO₄ in simulated eclampsia often perform other tasks effectively, for example, safe patient positioning and administering supplemental oxygen.¹⁷
• A simulated eclamptic case does not need expensive or high-fidelity models. Any amateur actor, including many doctors and midwives, can simulate seizure, unconsciousness and postictal uncooperativeness. The latter part may provide humour and/or psychotherapy.
• Research confirms that hospital staff actually get more out of content-appropriate team exercises, such as an eclampsia drill than ‘team-building’ exercises that may seem out of context, unduly theoretical or resembling pop-psychology.^15,17,18

How to deliver

Elective delivery is either induction of labour or elective caesarean. The choice is determined by many considerations including fetal presentation; predicted fetal tolerance for labour; likely time to delivery versus anticipated rate of clinical deterioration; anticipated family size; possible future childbearing issues; and patient preference. Advancing gestational age and confidence in fetal health usually allows a trial of labour, but vaginal delivery can sometimes be achieved safely at premature gestation too. Elective epidural helps stabilise blood pressure and allows anaesthesia if assisted delivery is required. Instrumental delivery is appropriate to shorten the second stage if maternal blood pressure rises dangerously with expulsive efforts.

When to deliver

The management choices for severe preeclampsia at extreme preterm gestations (for example, under 25 weeks) are:

• Expectant management anticipating greater fetal maturation while vigilantly watching for maternal deterioration. Realistically one to three weeks extra gestation might be obtained (sometimes less, rarely more), but severe maternal morbidity or even mortality may occur in one quarter to three quarters.^19,20
• Interrupting the pregnancy with the least traumatic birth for the fetus, usually by caesarean section (likely to be upper segment) following betamethasone for fetal lung maturation.
• Interrupting the pregnancy with the least traumatic birth for the mother, usually by misoprostol induction of labour.²⁰

Decisions around delivery at borderline viability are best discussed in a multidisciplinary meeting, considering both fetal and maternal issues. Fetal prognosis is affected by gestational age, fetal weight and any other complicating factors such as fetal compromise, multiple pregnancy or known fetal anomalies. Maternal issues include current health and likelihood of deterioration in the absence of delivery, as well as possible future childbearing. The views of the pregnant woman and her family, obstetrician and neonatologist need to be taken into account, along with resource availability and any local legal and ethical constraints.

From 26 weeks, or sometimes earlier, fetal interests become weighted similar to maternal interests: misoprostol is not usually used unless there are lethal anomalies such as trisomy 13. Betamethasone reduces hyaline membrane disease, intraventricular haemorrhage and necrotising enterocolitis at less than 34 weeks.²⁴ MgSO₄ benefits the fetus as well as the mother by lowering the incidence of neurodevelopmental delay, especially of infants born at less than 32 weeks.²⁵ Lower, rather than upper segment caesarean section becomes more achievable with advancing gestation. Expectant management may improve perinatal outlook considerably and slightly increase the chance of vaginal birth, but extreme care must be taken not to risk maternal health with this approach.^19,20 Beyond 34 or more completed weeks, severe PET usually justifies delivery.²⁰

After 37 weeks pregnancy, pregnancy induced hypertension or mild PET warrants prompt induction of labour to avoid the development of severe PET.²¹ A randomised controlled trial of induction versus expectant management showed greatest benefit of induction for women with an unfavourable cervix.²¹ This surprising result likely reflects the relatively slow rate of spontaneous cervical ripening and labour compared with the faster rate of disease progression to severe hypertension. Reassuringly, liberal induction for mild PET did not contribute to the simplistically termed ‘cascade of intervention’: the caesarean section rate was the same or lower and the unassisted vaginal birth rate the same or higher for women who were randomised to early induction compared women randomised to expectant management.²¹

Psycho-social issues after delivery

The impact of severe PET on psychosocial well-being should not be underestimated.

The volunteer-run Australian Action on Pre-Eclampsia (AAPEC) group was founded in 1993 by two mothers grieving the death of their babies due to preeclampsia. Their website (www.aapec.org. au/stories/index.php) contains numerous patient stories confirming that the emotional impact of preeclampsia can be huge. Postnatal depression (PND), judged by informal self-report, was at least as common as the background population (15 per cent) for women who participated in the Magpie Trial in low perinatal mortality countries similar to Australia and New Zealand.²² In contrast, a Dutch study found that preeclampsia conferred a two to three-fold increase risk for PND.²³ The possibility of post-traumatic stress disorder is real.

The obstetrician can help with debriefing and by helping a woman understand the nature or preeclampsia and give reasonable advice about future pregnancies.