Individually Tailored Prophylaxis Using a Risk Score for the Management of Pregnant Women with Increased Risk of Venous Thromboembolism

Patients with thrombophilia and/or a history of venous thromboembolism (VTE) exhibit a high risk of thrombosis during pregnancy. A risk score for pregnancies with increased risk of VTE was previously described by our group (1,2). The present work reports the results of a prospective study, evaluating the efficacy and the safety of the prophylaxis strategy based on the same risk score, in 542 pregnancies at high risk of VTE, managed between 2005 and 2015 in Lyon University Hospitals.

Among 445 patients included in the study, 26 had several pregnancies during the study period. The mean age of the study population was 33±4.8 years, 132 women (29.7%) were older than 35 years. Fifty three women had a BMI of 30 or over and 61 were smokers. Among these 445 patients, 279 had a personal history of VTE (62.7%), 299 patients (67.2%) had a thrombophilia marker and 131 (29.4%) thrombophilic women had a personal history of VTE.

During pregnancy, patients were assigned to one of three prophylaxis strategies according to the risk scoring system. Compression stockings were worn by the majority of the patients throughout the pregnancy and during the postpartum. In antepartum, LMWH prophylaxis was prescribed to 64.5% of patients with high risk of VTE. Among them, 34.4% were treated in the third trimester only and 30.1% were treated throughout pregnancy. In postpartum, all patients received low molecular weight heparin (LMWH) prophylaxis for at least 6 weeks.

In this cohort, two antepartum-related VTE (0.37%) and four postpartum-related VTE (0.73%) occurred. One of the ante-partum related VTE was occurred in a patient who was on LMWH prophylaxis with enoxaparin 40mg/day for a personal history of spontaneous pulmonary embolism and homozygous prothrombin G20210A mutation. Despite well conducted LMWH prophylaxis, the patient had a distal deep vein thrombosis (DVT) at week 28. The second VTE was a proximal DVT during a bed resting in the eighth month of pregnancy in a patient with heterozygous FV Leiden mutation and a history of proximal DVT. According to the risk score, LMWH prophylaxis was required during bed-resting but it was not prescribed by the obstetrician. Among four postpartum-related VTE, 3 occurred after the 6 weeks of LMWH prophylaxis, between weeks 8 and 12 of the postpartum period and one was a ovarian vein thrombosis. No case of pulmonary embolism was observed during the study period. The rate of bleeding was 0.37%, no serious bleeding requiring transfusions or surgery was occurred during the study period. There was no evidence of heparin-induced thrombocytopenia or osteoporosis.

The use of a risk score may provide a rational decision process to implement safe and effective antepartum thromboprophylaxis in pregnant women at high risk of VTE

1. Dargaud, Y., Rugeri, L., Ninet, J., Negrier, C. & Trzeciak, M.C. Management of pregnant women with increased risk of venous thrombosis. International Journal of Gynaecology and Obstetrics 2005, 90,203-207

2. Dargaud, Y., Rugeri, L., Vergnes MC, Arnuti B, Miranda P, Negrier, C., Ninet, J., Trzeciak, M.C. A risk score for the management of pregnant women with increased risk of venous thrombomebolism: a multicenter prospective study. Br J Haematol 2009;145:825-35