Blood, 1 August 2002, Vol. 100, No. 3, pp. 741-742
Recurrent venous thromboembolism and pregnancy
Current guidelines with respect to antepartum anticoagulation
for women who have had a previous episode of venous thromboembolism (VTE) are not well defined, in part because the degree of risk has not
been established in large clinical studies. Anticoagulation is
recommended during the postpartum period for this patient group, since
thrombotic risk is considered to be substantially increased. Pabinger
and colleagues (page 1060) have addressed the risk for recurrent VTE
during the antepartum period in a retrospective study of 109 women with
a history of an episode of VTE who were followed for a total of 1014 years, of which 73 observation years occurred during pregnancy. The
postpartum period was excluded for analysis, since anticoagulation
during that time was recommended. In this study, 40% of the women
tested positive for factor V Leiden and an additional 20% had another
type of thrombophilia. In this group of 109 women, the recurrence
rate of VTE in the antepartum period was 10.9 episodes per 100 patient
years. Risk for recurrence was not necessarily based on the presence of thrombophilia.
Although not discussed in this paper, another reason to consider
antepartum anticoagulation in women with thrombophilia is to reduce the
likelihood of other complications such as pre-eclampsia, abruptio
placentae, and fetal loss. The impact of anticoagulation on these
adverse outcomes is unknown other than for women with the
antiphospholipid syndrome.
The authors mention low molecular weight heparins (LMWHs) for
prophylaxis; these agents are commonly used in pregnancy although not
officially approved by the Food and Drug Administration in this
clinical setting. Pabinger et al's study supports the need for a
large, well-designed trial to define the risk-benefit ratio of
antepartum anticoagulation, most likely with a LMWH, in women with and
also without underlying thrombophilia who have had previous VTE.
Barbara Alving
National Heart, Lung, and Blood
Institute
