Samples collection and angiogenic factors measurement
At admission and before delivery (within 12 hours), a 5 ml peripheral
maternal blood sample was obtained. Serum was separated by
centrifugation at 2000 g for 10 min at room temperature, and samples
were immediately stored at -80ÂșC until assayed at an independent
laboratory.
Maternal serum concentrations of sFlt-1 and PlGF were determined by the
fully automated Elecsys assays for sFlt-1 and PlGF on an
electrochemiluminescence immunoassay platform (Cobas analyzers, Roche
Diagnostics). In all the kits, the intra-assay precision was
<4% for both assays and the inter-assay precision was
2.3-5.6% and 2.4-4.6% for sFlt-1 and PlGF assays respectively.
Longitudinal changes were quantified by calculating delta values: (level
at delivery - levels at admission)/days from admission to delivery.