Dr Fran Harlow, Consultant in Obstetrics and Maternal Medicine Lead for the Norwich Regional Maternal Medicine Centre shares the following expert insight with Hospital Hub…
Pre-eclampsia is a pregnancy complication characterised by hypertension and proteinuria, and is a leading cause of maternal morbidity and mortality worldwide for both mothers and their babies, especially in developing countries. The placenta is the cause of the disorder, and so the only effective treatment for pre-eclampsia is the delivery of the baby. For decades, diagnosing this condition has relied on frequently checking blood pressure and urine protein concentration, and on regular blood tests that detect maternal organ damage, since most women with pre-eclampsia are asymptomatic. Suspected pre-eclampsia often requires pregnant women to be regularly reviewed to monitor their condition either in the community or at the hospital, with low thresholds for hospital admission for observation, especially in more rural areas. This is an unwelcome burden, particularly for women experiencing discomfort at advanced stages of gestation, when pre-eclampsia more commonly presents. Adverse maternal and foetal outcomes are avoidable only with significant maternal intervention, and so the inevitable result of suspected pre-eclampsia is the increased use of maternity unit time and resources, putting further strain on already busy services.
Measurement of placental growth factor (PLGF) can be used as an adjunct to the established laboratory tests in equivocal cases of pre-eclampsia after 20 weeks and prior to 35 weeks of gestation. A high PLGF result is considered normal and suggests the development of pre-eclampsia and the progression to delivery in the next 14 days is unlikely. Instead, the patient can then be told that she has ‘gestational hypertension’, which does not carry the same risks for her or her baby as pre-eclampsia.
Following the release of NICE guidelines on diagnosing pre-eclampsia in 2016,1 the Norfolk and Norwich University Hospitals NHS Foundation Trust decided to introduce a new NICE approved, point-of-care (POC) blood test for PLGF into its Delivery Suite at Norfolk and Norwich University Hospital (NNUH). Used alongside regular blood pressure monitoring, the test can be performed and analysed by the midwives, and takes approximately 15 minutes. If the result shows a low risk for pre-eclampsia, and the woman’s laboratory tests are also reassuring, she can be sent home with a blood pressure monitor and a ‘traffic light’ action card.
L-R: Elaine Mitchell and Theresa Hornsby
Patients can then test themselves on a regular basis, rather than repeatedly attending NNUH for check-ups, freeing up clinic time in the Maternity Assessment Unit and alleviating staff workloads, as well as minimising disruption to the patients’ work and home lives. Crucially, this novel, evidence-based approach means that this potentially fatal condition can be evaluated on the same day – relieving maternal stress and allowing women to regain some autonomy over their pregnancy. As a result, PLGF testing is now part of the standard practice for assessing women with hypertension in pregnancy at NNUH.
NNUH chose POC testing over a lab-based, ratiometric detection of PLGF because the lab-based platform did not offer random-access loading. This would have required either a batch of PLGF tests to be run – which lacked the necessary time sensitivity – or that the entire instrument was occupied to perform a single PLGF measurement, which was time-consuming and prevented key equipment from being used for other crucial analyses. Installation of a POC testing platform in the Delivery Suite was therefore an obvious solution.
Midwife Hayley Summerfield and patient Annie Minton
The system has proved to be user-friendly and intuitive, minimising the amount of time required to learn to use it. The introduction of POC testing has been very successful, having a significant positive impact on maternal outcomes, reducing antenatal visits and hospital admissions required, as well as lowering the number of interventions for suspected pre-eclampsia – such as induction of labour. As a result, NNUH is now a strong advocate for this approach, and is supporting other hospitals locally, and even some further afield, in their transition to POC PLGF testing.
This ground-breaking test is a major development for obstetrics, and forms part of a wider clinical toolbox to help evaluate pre-eclampsia. Of course, PLGF is a relatively new analyte, and so it is paramount to carry out more research in the coming years to determine whether POC tests do indeed provide other health benefits. It is encouraging that so much progress is being made in a short space of time, and early findings certainly show a lot of future promise for POC PLGF testing.
References
1National Institute of Health and Care Excellence (NICE). (2016). PlGF-based testing to help diagnose suspected pre-eclampsia. Triage PlGF test, Elecsys immunoassay sFlt-1/PlGF ratio, DELFIA Xpress PlGF 1-2-3 test, and BRAHMS sFlt-1 Kryptor/BRAHMS PlGF plus Kryptor PE ratio). DG23. Available at: https://www.nice.org.uk/guidance/dg23 (Accessed: 19 May 2022).
