Activated protein C resistance (factor V Leiden) associated with thrombosis in pregnancy

Our purpose was to evaluate activated protein C resistance phenotype and genotype among patients with thrombosis during pregnancy and the puerperium.

This observational study was conducted prospectively during a 2-year period (July 1993 to June 1995) in a preselected population. All patients admitted to our high-risk pregnancy unit with a diagnosis of deep vein thrombosis, pulmonary emboli, transient ischemic attack, and cerebrovascular accident during pregnancy and the puerperium were included. Prothrombin time, partial thromboplastin time, fibrinogen levels, protein C, protein S, antithrombin III, functional test for activated protein C resistance, and factor V Leiden mutation by polymerase chain reaction were performed on each patient.

Fifteen patients were included. Seven (46.6%) patients were positive for activated protein C resistance (factor V Leiden). All other coagulation studies were negative for all patients. All patients with activated protein C resistance had a venous thrombotic event, deep vein thrombosis, or pulmonary emboli, and only one had a cerebrovascular accident on the basis of sagittal sinus thrombosis. Only two of the activated protein C resistance-negative patients had venous thrombosis (pulmonary emboli). The remaining six patients had transient ischemic attacks or cerebrovascular accidents. For the subgroup with venous thrombosis during pregnancy and the puerperium, the incidence of activated protein C resistance (factor V Leiden) was 78%.

This study demonstrates the incidence of factor V Leiden in a selected population in whom thrombotic events developed during pregnancy and the puerperium. This small-scale study provides justification for a large cohort study that will identify women with factor V Leiden and determine their risk for thrombosis during pregnancy and the puerperium. We believe that factor V Leiden should be evaluated in conjunction with thrombotic events in the pregnant woman.