Use of Antithrombotic Agents During Pregnancy: Dose of heparin
However, there is a concern that a dose of heparin 5,000 U subcutaneously ql2h may be insufficient in high-risk situations because it does not reliably produce detectable heparin levels. There is also published level III data that more intense heparin therapy, in doses that produce plasma heparin levels (measured as anti-factor Xa activity) of 0.1 to 0.2 U/mL, is associated with low recurrence rates in pregnant women with previous VTE. The advantage of adjusted-dose heparin is that it is more likely to produce a consistent anticoagulant effect throughout pregnancy, although its use is likely to increase the risks of bleeding and osteoporosis and requires lab monitoring. Until comparative clinical trials are performed, it is our belief that either approach is reasonable. In addition, low recurrence rates have been reported with the use of LMWH once daily.
In pregnant women with previous VTE who cannot use or refuse to use heparin, an alternative is clinical surveillance there canadian pharmacy. The safety of this approach is being tested in a large cohort study based at McMaster University and is dependent upon detection and treatment of VTE before the development of major PE. This approach is supported by an overview that suggested that fatal PE as the initial manifestation of recurrent VTE was rare (approximately 5%), particularly in otherwise healthy individuals. We particularly favor this approach in women with previous VTE that occurred in association with a transient risk factor.
Management of Pregnant Women With Prosthetic Heart Valves
Women of childbearing potential with valvular heart disease pose problems because of the lack of reliable data on the efficacy and safety of antithrombotic therapy during pregnancy. In a recent retrospective level V survey describing outcomes in pregnant women with mechanical heart valves, the following was concluded: (1) that warfarin was safe and not associated with embryopathy; and (2) that heparin was associated with more thromboembolic and bleeding complications than warfarin.