Thrombophilia Assessment and Pregnancy: Determination of Reference Values for dRVVT in Pregnant Women

Pregnancy is associated with significant changes in several aspects of haemostasis, especially an imbalance between procoagulant and anticoagulant factors. These changes contribute to creating a state of hypercoagulability, mainly at the end of pregnancy and during the post-partum period, protecting pregnant women from delivery haemorrhage, but exposing them to a major thromboembolic risk.

Vascular diseases of pregnancy (VDP) are obstetric diseases which are linked to an ischaemic origin associated with placental thrombosis. These include pre-eclampsia, retroplacental haematoma, intrauterine growth retardation and even foetal death in utero. A number of risk factors have been identified for these VDPs, some of which have extremely serious consequences, the main one being antiphospholipid syndrome (APS).

The diagnosis of VDP in a current or previous pregnancy requires close monitoring and joint management by an obstetrician, haemostasis physician, internist and medical biologist, particularly in terms of pre, peri- and post-partum anticoagulation in patients at increased risk of thromboembolism.

The aim of treating APS during pregnancy is : to reduce the occurrence of maternal arterial or venous thrombotic complications in one hand and in the other hand to reduce the occurrence of obstetric complications, which are responsible of a significant morbimortality rate. The detection of a possible APS during pregnancy will therefore determine the specific management of patients.

The latest guidelines from the Groupe Français d'Etude sur l'Hémostase et la Thrombose (GFHT) in 2022 recommended a diluted Russell's viper venom time (dRVVT) and an activated partial thromboplastin time (APTT) measured using a sensitive reagent such as silica (SCT) should be used to assess the presence of LA.