Stability of first trimester placental growth factor in serum and whole blood

Background Placental growth factor (PlGF) is a proposed first‐trimester screening marker for pre‐eclampsia. This study investigates the stability of PlGF in serum and whole blood at typical routine storage temperatures. Methods Serum pools were stored at refrigerator temperature, room temperature or 30 °C for up to 30 days, or exposed to up to six freeze–thaw cycles. Whole blood was stored at room temperature or 30 °C for up to 6 days. PlGF was quantified using a DELFIA Xpress analyser. Results Placental growth factor levels increased over time, seemingly because of the dissociation of PlGF bound to a soluble binding protein, sFlt‐1. Increase was slow in serum at refrigerator temperature, remaining stable (less than 10% change from start point) for at least 30 days. At room temperature PlGF was stable for 3.3 days and at 30 °C for 1 day. Serum PlGF remained stable for at least six freeze–thaw cycles. In whole blood, instability was worse, being stable for only 19.4 h at room temperature and just 3.3 h at 30 °C. Conclusion Routine screening of sample handling requires careful monitoring. However, no extra precautions need to be taken when PlGF is used for pre‐eclampsia screening run alongside existing first trimester aneuploidy screening programs that include hCGβ. Copyright © 2011 John Wiley & Sons, Ltd.