Medical problems in pregnancy 37
Modern management of postpartum hypertension MANJU CHANDIRAMANI, ANDREW SHENNAN AND JASON WAUGH Current evidence focuses mainly on hypertensive disorders that develop in the antenatal and intrapartum period, while hypertension in the postpartum period is a contentious and poorly managed area. The authors outline what is known about the incidence, risk factors, optimal management and implications of postnatal hypertensive disorders. Dr M. Chandiramani, MB ChB, BSc, Clinical Research Fellow, Department of Women’s Health, St Thomas’ Hospital, London; Professor A.H. Shennan, MD, MB BS, FRCOG, Professor of Obstetrics, King’s College London; Mr J.J.S. Waugh, BSc, MB BS, DA, MRCOG, Consultant/Honorary Senior Lecturer, Obstetrics and Maternal Medicine, Royal Victoria Hospital, Newcastle upon Tyne.
women with pregnancy-induced hypertension Iwillnormost pre-eclampsia, the hypertension and/or proteinuria resolve within 12 weeks after delivery. However, if a woman remains hypertensive, a diagnosis of chronic hypertension is likely and further investigations and referral to a physician are warranted. GPs should ensure that every postnatal woman they see who had pregnancyinduced hypertension or pre-eclampsia complicating their pregnancy has a blood pressure measurement and urine protein dipstick at their six-week postnatal visit to ensure a return to normotension or an accurate classification of their hypertensive disorder (Figure 1). Hypertension/pre-eclampsia occurring for the first time in the postnatal period Hypertensive disorders can develop during pregnancy, labour and the puerperium. Current evidence focuses mainly on the antenatal and intrapartum period and its management (see the previous article in this series1). Very little information is available regarding the incidence, risk factors, optimal management and subsequent outcome of postnatal hypertensive disorders, particularly new preeclampsia diagnosed postnatally. It is recognised that the postpartum period continues to pose a risk of pre-eclampsia, with up to 44 per cent of eclamptic convulsions occurring in this period.2,3 Most will occur within 48 hours after delivery, with only 26 per cent of seizures developing more than 48 hours after delivery.2 In Sweden, 96 per cent of women with postpartum eclampsia present within the first 20 hours of delivery.4 Therefore, women with pre-eclampsia should be closely monitored initially in the postpartum period with four-hourly observawww.tugsh.com
Figure 1. Ambulatory blood pressure monitoring may be needed if another pregnancy is planned in a woman who has experienced postpartum hypertension.
tions of their blood pressure; early discharge from hospital (ie less than 48 hours after delivery) is to be discouraged. The incidence of pre-eclampsia first appearing during the postpartum period is unknown. In a review of 151 cases, Matthys et al. found an incidence of 5.7 per cent.5 This highlights the importance of instructing women at the time of discharge from hospital regarding the risks of pre-eclampsia. They should be aware of symptoms such as epigastric pain, headaches and visual disturbances, and be advised to seek immediate medical advice in the presence of these symptoms. Haemolysis, elevated liver enzymes and low platelet count (HELLP) can also occur during the postpartum period, with 30 per cent of cases presenting after delivery.2,3 Monitoring of blood pressure and proteinuria should continue postpartum through regular visits to the midwife. Blood pressure changes in the postpartum period The exact cause of pre-eclampsia is unknown. Evidence suggests that it is a result of an increased resistance in the utero-placental circulation resulting in an impaired blood Trends in Urology Gynaecology & Sexual Health
September/October 2007
38 Medical problems in pregnancy
flow and subsequent poor placental perfusion. Accordingly, one would presume that once the baby and placenta are delivered, the pathological process would no longer continue, alleviating the threat of pre-eclampsia and eclampsia. Clearly, this is not always the case. Following an uncomplicated pregnancy, the arterial blood pressure rises progressively during the first five days.6,7 This may relate to the profound fluid shifts that occur in the puerperium. In the first few days after delivery, mobilisation of extravascular fluid is observed, which results in a rise in the intravascular volume, and consequently an increase in the blood pressure.4 In a pregnancy complicated by pre-eclampsia, these changes will be occurring on a background of an already compromised vascular system of diffuse vasospasm secondary to endothelial cell damage. This shift of fluid from the extravascular to the intravascular space may also increase the risk of pulmonary oedema, cerebral oedema and eclampsia. Furthermore, pre-eclamptic women show persistently elevated central retinal artery systolic velocity in the postpartum period, suggesting the presence of distal vasoconstriction. Doppler studies of the cerebral arteries demonstrate that vascular instability in pre-eclampsia is a longstanding problem, at least in the microvascular arteriolar beds of the cerebral circulation.8 It is interesting that these changes appear to resolve spontaneously before six weeks’ postpartum. Once these pathophysiological changes are accounted for and considered, it is easy to understand why early discharge from medical care has been associated with occasional maternal death from pre-eclampsia/eclampsia occurring for the first time in the postnatal period. Management of postpartum hypertension The principles of management of postpartum hypertension are the same as for antepartum hypertension, the aim being to prevent severe hypertension (diastolic blood pressure >120mmHg on any one occasion or diastolic blood pressure >110mmHg on two consecutive occasions more than four hours apart). Extreme hypertension (mean arterial pressure >140mmHg) causes direct arterial injury, which predisposes to cerebral haemorrhage. The aim of emergency antihypertensive treatment is to maintain blood pressure
