Sta r evolution instrument

After women arrived at the labour ward, blood was collected in tubes containing 0.13 M citrate either from direct venipuncture or from intravenous cannulae. The blood samples were centrifuged at 2000 g at room temperature for 20 min. Plasma was frozen at -70°C until analysed. Fibrinogen concentration in plasma was analysed in batches with the Clauss method (STA ® Fibrinogen 5, Diagnostica Stago, Asnières sur Seine, France) on a STA-R Evolution instrument (Diagnostica Stago). The non-pregnant reference range is 2.0-4.5 g litre -1 . Estimated blood loss (EBL) at delivery and postpartum were determined by the responsible midwife by weighing surgical sponges and pads and by measuring collected blood.
Patient characteristics (age, body mass index, parity, gestational week at delivery, epidural analgesia, diagnosis and bleeding at delivery) were obtained from electronic patient records (Obstetrix, Siemens AB, Healthcare Sector, Upplands Väsby, Sweden). Severe postpartum haemorrhage was defined as EBL >1000 ml. 4 11 Predefined subgroups included women with different age, body mass index, parity, gestational weeks, fibrinogen concentrations, preeclampsia, induction of labour, use of oxytocin stimulation, epidural analgesia, Caesarean section and women undergoing uterus exploration (Table 2).