Pre eclampsia

The National Institute for Health and Care Excellence (Nice) in the UK has published its final guidance recommending two blood tests to eliminate the occurrence of pre-eclampsia during pregnancy.

During normal pregnancy, placental growth factor (PlGF) increases, however, a lack of rise in the PlGF level, indicates that the placenta is not developing properly, marking the occurrence of pre-eclampsia.

NICE recommends Triage PlGF test (Alere) and the Elecsys immunoassay sFlt-1/PlGF ratio (Roche Diagnostics) blood tests to help detect occurrence of pre-eclampsia in women between their 20th and 35th week of pregnancy.

Maternal and Fetal Health Research Centre, Central Manchester Foundation Trust senior lecturer consultant obstetrician and specialist diagnostics assessment committee member Dr Jenny Myers said: "The tests will be extremely valuable to help rule out pre-eclampsia before the 35th week of pregnancy, when approximately 1/3 of women with pre-eclampsia are diagnosed.

"Doctors will need to be clear with patients, depending on which test is used, the result is only valid for seven to 14 days and neither test definitively rules out pre-eclampsia for the rest of the pregnancy.

"However these tests represent a great stride forward in the management and treatment of pre-eclampsia."

Pre-eclampsia, and associated eclampsias are considered to be the second leading cause of direct maternal deaths in the UK. It occurs when the placenta does not develop properly owing to decreased blood supply.

High-blood pressure (hypertension) and the presence of protein in the urine (proteinuria) are the symptoms indicative of pre-eclampsia.

It can cause liver, kidney and lung failure, problems with blood clotting and strokes later in life. Women who develop pre-eclampsia during pregnancy are said to be more vulnerable to cardiovascular disease later in life and if not treated, pre-eclampsia, during pregnancy can aggravate to eclampsia.

Hypertension and pre-eclampsia can cause growth problems in the baby, premature birth, or stillbirth.

The blood tests detect changes in the blood by measuring the level of PIGF which is a protein triggering the development of new blood vessels in the placenta.

"The tests will be extremely valuable to help rule out pre-eclampsia before the 35th week of pregnancy, when approximately 1/3 of women with pre-eclampsia are diagnosed."

In pre-eclampsia levels of PlGF can be abnormally low and could be an indicator that the placenta is not developing properly.

The Elecsys immunoassay sFlt-1/PlGF ratio measures a protein called soluble FMS-like tyrosine kinase-1 which stops other proteins that help to form blood vessels, like PlGF, from working.

In pre-eclampsia if sFlt-1levels are higher than those seen in normal pregnancy it could be an indicator the placenta is not developing as it should.

The guidance released by NICE recommends further research to be done on using these tests in women with suspected pre-eclampsia to help diagnose pre-eclampsia.

Image: Micrograph displays hypertrophic decidual vasculopathy, as seen in pregnancy-induced hypertension. Photo: courtesy of Nephron.