PlGF-based testing has been recommended by NICE to both rule-in and rule-out the short-term development of pre-eclampsia
Placental growth factor (PlGF)-based testing has been recommended by the National Institute for Health and Care Excellence (NICE), in conjunction with standard clinical assessment, to help rule in or rule out women with suspected preterm (i.e., between 20 weeks and 36 weeks and 6 days of pregnancy) pre‑eclampsia.
Pre-eclampsia is associated with increased adverse maternal and perinatal outcomes and one analysis suggests that approximately 15-25% of women initially diagnosed with gestational hypertension will develop pre-eclampsia. The condition is characterised by hypertension and proteinuria and either symptom alone presents a risk of developing pre-eclampsia. Other symptoms suggestive of pre-eclampsia include headache, visual disturbances, epigastric pain, oedema and oliguria. Failure to diagnose pre-eclampsia can lead to potentially life-threatening complications including eclampsia, HELLP syndrome (haemolysis, elevated liver enzymes and low platelets), disseminated intravascular coagulation, stroke or organ dysfunction. According to a report by Action on Pre-eclampsia, globally, the condition accounts for 14% of all maternal deaths and the group has welcomed the fact that PlGF-based testing will become available on the National Health Service in England and Wales.
PlGF is an angiogenic protein secreted by the syncytiotrophoblast (i.e., placental barrier between maternal and foetal blood that allows exchanges in nutrients and gases) and which promotes placental angiogenesis. PlGF levels are low in the first trimester of an uncomplicated pregnancy and increases from week 11 to 12 onwards to a peak at week 30, after which it decreases. However, both serum and urinary PlGF levels are found to be decreased in women both at the time of diagnosis with pre-eclampsia.
NICE has recommended PlGF-based testing with four tests: DELFIA Xpress PLGF 1‑2‑3; DELFIA Xpress sFlt‑1/PLGF 1‑2‑3 ratio; Elecsys immunoassay sFlt‑1/PLGF ratio; and the Triage PLGF Test, adding how modelling shows that all these tests are cost effective compared with standard assessment when used to help diagnose (rule in) or exclude (rule out) preterm pre‑eclampsia. Consequently, these tests are now recommended to help plan safe care and a safe birth in pre-eclampsia as well as to identify women unlikely to develop pre-eclampsia, thus reducing unnecessary hospitalisation. The NICE guidance adds that because these tests might work differently in multiple pregnancy, and further research to necessary to determine how well the tests might work in this group.
A further caveat is that there is insufficient enough evidence as to whether or not the test should be repeated and NICE has therefore recommended only single testing for women who present with possible symptoms of preterm pre-eclampsia and recommended further research to ascertain if repeat testing improves outcomes.