Elecsys platform

Information about the study was provided to pregnant women attending antenatal care at the study setting. Subsequently, pregnant women booked for CD were offered the opportunity to participate in the study. Again, each patient gave informed consent before participation. Within 48 hours (preferably within 24 hours) before CD, 4-item PSS score and VNRS were obtained from each participant. Thereafter and within the same 48 hours (preferably within 24 hours) before delivery, peripheral venous blood was collected from each patient for measurement of serum concentration of sFlt-1 and PIGF.
Each blood sample was collected with an aid of a vacutainer in SST II advance yellow with gel tube. The samples were centrifuged in the laboratory at room temperature for 10 minutes at a speed of 3000 rpm using Rotina 380 R benchtop centrifuge (Andreas Hettich GmbH & Co. KG, Germany). The serum was collected in a cryotube, stored at −20 °C and measurement of the angiogenic factors were performed in batches at an independent laboratory (Ampath Laboratory, Durban, South Africa) within one month using Roche Elecsys Platform (Roche Diagnostics, Germany).
Within 48 - 72 hours postpartum, 4-item PSS score was recorded. On postpartum days 0, 1, 2 and 3, VNRS scores were obtained. A trained midwife collected the data. The principal investigator supervised and also assisted with data collection.

A 250μl ethylenediaminetetraacetic acid plasma sample previously unthawed or only thawed once was used for plasma analysis. Hs-cTnT was measured at Exam 1 (n=6873) and Exam 3 (n=3577). Measurements were performed at the University of Maryland using the Cobas e601 (Roche Diagnostics) and details have been described previously.^{13 (link)} The interassay coefficients of variation (CVs) observed for the MESA cohort measurements were 3.6% at 28 ng/L and 2.0% at 2154 ng/L. Measurements at the 3 ng/L, defined as the limit of detection (LOD) for this instrument, were well within the reportable range for the hs-cTnT used in this study.
NT-proBNP was measured in 5597 participants at Exam 1 and 4996 participants at Exam 3. Measurements were performed at the Veteran’s Affairs San Diego Healthcare System (La Jolla, CA) using the Elecsys platform (Roche Diagnostics). The intra- and inter-assay coefficients of variation were as follows: at 175 pg/ml, 2.7% and 3.2%; at 355 pg/ml, 2.4% and 2.9%; at 1,068 pg/ml, 1.9% and 2.6%; and at 4,962 pg/ml, 1.8% and 2.3%, respectively. Details for NT-proBNP measurement have been previously reported.^{8 (link)}