Blood Test Can Rule Out Preeclampsia in Pregnant Women

Preeclampsia is difficult to diagnose and manage and physicians estimate that around 80% of pregnant women suspected of having preeclampsia do not go on to develop it. Many of those women are unnecessarily hospitalized while other preeclamptic patients are only detected at a very late stage, endangering both them and their babies.

An international team of scientists led by those at the Campus Virchow–Klinikum Charité (Berlin, Germany) performed a prospective, multicenter, observational study to derive and validate a ratio of serum soluble fms-like tyrosine kinase 1 (sFlt-1) to placental growth factor (PlGF) that would be predictive of the absence or presence of preeclampsia in the short term in women with singleton pregnancies in whom preeclampsia was suspected (24 weeks to almost 37 weeks of gestation).

The study was designed to derive and validate a cutoff point of the sFlt-1: PlGF ratio for the prediction of the short-term absence or presence of preeclampsia, in a two-phase approach (development and validation). In the development phase, the scientists used data from 500 participants to derive the sFlt-1: PlGF ratio cutoff point for the prediction model, which was validated with the use of data from 550 additional participants. Maternal serum levels of sFlt-1 and PlGF, measured in pg/mL were determined by means of the fully automated Elecsys assays for sFlt-1 and PlGF on an electrochemiluminescence immunoassay platform (cobas e analyzers, Roche Diagnostics, Basel, Switzerland) and were used to calculate the sFlt-1:PlGF ratio.

In the development cohort (500 women), the teams identified a sFlt-1: PlGF ratio cutoff of 38 as having important predictive value. In a subsequent validation study among an additional 550 women, a sFlt-1: PlGF ratio of 38 or lower had a negative predictive value (i.e., no preeclampsia in the subsequent week) of 99.3%, with 80.0% sensitivity and 78.3% specificity. The positive predictive value of a sFlt-1: PlGF ratio above 38 for a diagnosis of preeclampsia within four weeks was 36.7% with 66.2% sensitivity and 83.1% specificity.

The authors concluded that a sFlt-1: PlGF ratio of 38 or lower can be used to predict the short-term absence of preeclampsia in women in whom the syndrome is suspected clinically. Manu Vatish, MB, ChB, DPhil, a Consultant Obstetrician and coauthor of the study, said, “A preeclampsia diagnosis can be extremely frightening for women and their families. The condition can be life-threatening and affects around 5% of all pregnancies. Preeclampsia symptoms are often nonspecific and, without a reliable test to diagnose the condition, many women are admitted to hospital unnecessarily.” The study was published on January 7, 2016, in the New England Journal of Medicine (NEJM).

Related Links:
Campus Virchow–Klinikum Charité
Roche Diagnostics