Preanalytical stability of maternal serum markers hCGβ and PAPP-A.

Down syndrome maternal serum marker screening is based on a risk calculation including the free β - human chorionic gonadotropin (hCGβ) and pregnancy-associated placenta protein type A (PAPP-A). The aim of this study was to define the pre-analytical conditions of stability of these markers both in whole blood at 15-25 ̊C and, after centrifugation, in serum at 4-8 ̊C. 158 patients were included in the study.