HEPTEST: a suitable method for monitoring heparin during pregnancy

Methods of monitoring heparin in pregnancy are problematic. The aim of this study was to assess the plasma HEPTEST as a rapid and reliable test for he parin monitoring in pregnancy. HEPTEST, activated partial thromboplastin ti me (APTT) and chromogenic anti-Xa assays were performed on individual hepar in-spiked plasma samples from two groups; normal non-pregnant women (n = 6) and normal pregnant women during the third trimester (n = 6). Heparin acti vity curves were established in plasma from both groups for low (< 0.3 IU/m l), intermediate (0.3-0.7 IU/ml) and high (> 0.7 IU/ml) heparin concentrati ons and validated by comparison with the anti-Xa chromogenic assay. Both th e APTT and HEPTEST demonstrated good correlation with anti-Xa levels across all heparin concentrations in both plasma groups (r range = 0.879-0.945). In comparison with the APTT, the HEPTEST showed better correlation with ant i-Xa levels at low concentrations of heparin (r values 0.933 vs 0.772, resp ectively). For both the APTT and HEPTEST there were significant differences between the clotting times in pregnant and non-pregnant plasma at a number of heparin concentrations. This data supports the plasma HEPTEST as an acc eptable alternative to the chromogenic anti-Xa assay for monitoring heparin thromboprophylaxis in pregnancy.