Pre-eclampsia mattersBMJ 2005; 330 doi: https://doi.org/10.1136/bmj.330.7491.549 (Published 10 March 2005) Cite this as: BMJ 2005;330:549
- Ian A Greer (), Regius professor of obstetrics and gynaecology
New guideline is simple, evidence based, and clinical, and should be used
Pre-eclampsia matters. In both the developed and the developing world, pre-eclampsia is important. It remains a leading cause of maternal and perinatal mortality and extensive morbidity. The reports of the Confidential Enquiry Into Maternal Deaths1 have identified deficiencies in care in relation to pre-eclampsia in successive reports since the 1950s. In this issue, the systematic review by Duckitt and Harrington quantifies the risk of pre-eclampsia associated with different factors present at the antenatal booking visit (p 565).2 The rationale is that this risk assessment will inform allocation of the woman to a suitable surveillance routine to detect pre-eclampsia.
The risk of pre-eclampsia is increased with a previous history of pre-eclampsia, pre-existing diabetes, multiple pregnancy, a family history for pre-eclampsia, a raised body mass index before pregnancy or at booking, raised blood pressure at booking, and the presence of anti-phospholipid antibodies. These risk factors are important, with relative risks of almost threefold for nulliparity and over ninefold for antiphospholipid antibodies. With a background incidence of 2-3%, this translates to absolute risks of 6% and almost 30%, respectively. In terms of early onset of disease, which carries the highest level of morbidity, the authors note that they may have underestimated the importance of these risk factors as studies often did not discriminate between early and late onset pre-eclampsia. Further, they could not study the interrelations between risk factors—for example, obesity—maternal age, and essential hypertension.
Clinicians spend a great deal of time and energy screening for problems in pregnancy—for example, syphilis, Rhesus iso-immunisation, and Down's syndrome—that have a much lower incidence than pre-eclampsia. So why have we failed when the identification of women at risk, and the diagnosis of pre-eclampsia, through measurement of blood pressure and urinalysis, is arguably the most important aspect of regular antenatal assessment? Complacency may play a part, as clinicians and women perhaps take for granted a healthy outcome of pregnancy, but we have undoubtedly failed to appreciate the risk factors, the protean presentations of this condition, its natural history, and the need for intervention. Many women do not realise why they are having their blood pressure measured. In addition, clinicians may see risk assessment and screening for pre-eclampsia as futile. The criteria for screening are that the condition must relate to an important health problem; the natural history should be understood and identifiable before the disease presents clinically; the screening test should be simple, safe, and acceptable; effective treatment must exist, with better outcomes than late treatment; and the treatment should be effective in reducing morbidity and mortality, acceptable, and cost effective. Not all these criteria are met for pre-eclampsia. However, the quantification of risk for different factors provided by this systematic review is welcomed.2
These evidence based risk factors have been used by the Pre-Eclampsia Community Guideline (PRECOG) Group to inform its community guideline, which is also published in this issue (p 576).3 These factors will allow early referral and a two tier schedule of assessment for signs of pre-eclampsia, complementing the NICE antenatal guideline.4 That absence of antenatal care is associated with poor outcome of pregnancy is now clear,5 but, perhaps surprisingly, we have little evidence to support the optimal frequency of antenatal care visits for identifying pre-eclampsia. In many patients it develops rapidly and can progress to a severe form within days of an adequate antenatal assessment. In view of the rapid development of pre-eclampsia in some women, we need to ensure that antenatal education makes women aware of the symptoms of pre-eclampsia and the importance of regular assessment. The guideline is aimed at those caring for pregnant women in the community, to raise awareness of the risk factors for and implications of pre-eclampsia, including the need for accurate diagnosis, assessment, and timely referral especially when proteinuria or severe hypertension are present. Once severe disease develops, many women require delivery within three days, although with intensive control of blood pressure a mean prolongation of pregnancy of 14 days is possible.6 The PRECOG guideline adopts a pragmatic approach to tackle this issue, presenting a clear synthesis of the evidence, albeit limited in terms of randomised trials, and a clear plan setting out whom and when to refer.
The strengths of the PRECOG guideline are its simplicity, its evidence base for risk assessment, its reliance only on clinical features for assessment, and its straightforward management plan. These features make it relevant not only in the United Kingdom but also in other countries. The weakness is that the available evidence to support intervention with more frequent assessment or by different healthcare professionals is limited in quantity and quality.
Purists may argue that screening for risk in early pregnancy and recommendations for the proposed frequency of antenatal screening visits does not meet all the criteria for screening. However, in 46% of maternal deaths and 65% of fetal deaths reported via the confidential inquiries into maternal deaths,1 different management would reasonably have been expected to alter the outcome. Many of these management problems arise in the community because of a failure to identify and act on established risk factors at booking and to recognise and respond to signs and symptoms consistent with pre-eclampsia. We may not have the answers in terms of the outcome from such intervention, but we cannot be complacent in the face of the recurrent deficiencies identified in the confidential inquiries. The pragmatic approach of PRECOG is essential because pre-eclampsia matters.