Assessment of coagulation in the obstetric population using ROTEM® thromboelastometry

Background: Assessment of maternal coagulation to determine suitability for neuraxial anaesthesia and management of obstetric haemorrhage remains a challenge. Thromboelastography provides point of care patient assessment of the viscoelastic properties of whole blood clotting and can assist the clinician in haemostatic decision-making. The study aim was to determine the ROTEM® thromboelastometer 95% reference limits for third trimester parturients and to compare these with non-pregnant female controls.

Methods: Following ethics committee approval and informed consent, citrated blood was sampled from 120 age-matched healthy pregnant and non-pregnant women. Thromboelastometry, using a ROTEM® point of care monitor, was performed with specific activators to measure the coagulation time (CT), clot formation time (CFT) and the maximal clot firmness (MCF) in order to evaluate the extrinsic (EXTEM® test) and intrinsic (INTEM® test) coagulation systems, as well as the fibrinogen contribution to coagulation (FIBTEM® test).

Results: After exclusions, data from 54 subjects in each group were analysed. Parturients had significantly lower haemoglobin values and platelet counts (P<0.01). Despite this, thromboelastometry exhibited significantly lower INTEM® CT (7.3%), INTEM® CFT (11.1%) and EXTEM® CFT (18.0%) in the pregnant group (P<0.001). MCF values were significantly higher (INTEM® (10.9%), EXTEM® (10.6%) and FIBTEM® (47.1%)) in the pregnant group compared to the non-pregnant group (P<0.0001).

Conclusions: ROTEM® thromboelastometry clearly demonstrates the hypercoagulability of pregnancy. Formal reference ranges for ROTEM® that may be potentially useful in the haemostatic management of the parturient are presented.