The effect of dalteparin on thromboelastography in pregnancy: an in vitro study.

Background: Dalteparin is often used for prophylaxis or treatment of venous thromboembolism during pregnancy, yet there is no laboratory test to accurately reflect its clinical activity. Thromboelastography is a point-of-care monitor of whole blood coagulation. The aim of this study was to determine if serial doses of dalteparin added in vitro to whole blood samples from term, pregnant women are detectable as changes in thromboelastography parameters.

Methods: Thirty healthy parturients presenting for elective caesarean section were recruited. Dalteparin was added to whole blood samples to yield final concentrations of 0 (control), 0.05, 0.25, 0.5, 0.75 and 1.0U/mL anti-Xa activity. Thromboelastography tracings were obtained for all six samples using the standard kaolin protocol.

Results: Significant differences were noted in median thromboelastography r time, k time, alpha angle and maximal amplitude between non-anticoagulated (⩽0.05U/mL) and samples ⩾0.5U/mL (P<0.05). The r time and k time presented with the highest sensitivities of 97.5 and 84.0, respectively.

Conclusion: This pilot study provides proof-of-concept that thromboelastography can discriminate differences in blood anticoagulated with varying doses of dalteparin in a dose-dependent manner. This suggests that thromboelastography may be a feasible monitor of anticoagulation in the presence of dalteparin in maternal whole blood and may potentially translate to a point-of-care test that can be used to determine real-time coagulation status in patients.