A less-intensive anticoagulation protocol of therapeutic unfractionated heparin administration for pregnant patients.

Affiliation

Division of Counseling for Medical Genetics, National Cerebral and Cardiovascular Center, 6-1 Kishibeshinmachi, Suita, Osaka, 564-8565, Japan. [Email]

Abstract

Heparin anticoagulant therapy for thromboembolic disorders during pregnancy is problematic due to unexpected adverse bleeding. To avoid bleeding, we have used a less-intensive anticoagulation protocol of unfractionated heparin (UFH). The protocol had a therapeutic activated partial thromboplastin time (APTT) ratio of 1.5-2.0 with the control value, a UFH dose of ≤ 30,000 U/day, and an antithrombin (AT) activity target of ≥ 70%. In the present study, we evaluated this protocol using an anti-Xa assay. We collected UFH-treated plasma samples from ten consecutive pregnant Japanese patients with current or previous thromboembolic disorders. Seven patients remained in the therapeutic APTT ratio range (heparin-sensitive [HS] group). The other three patients had difficulty remaining within the therapeutic range (heparin-resistant [HR] group). In the HR group, two had AT deficiency and one had congenital absence of the inferior vena cava. Of the HS and HR samples, 73% and 31%, respectively, were within the therapeutic anti-Xa activity range 0.3-0.7 U/mL, indicating difficulty for the HR group to remain within the therapeutic range. Neither major bleeding nor symptomatic thromboembolic episodes occurred in either group. These findings suggest that the less-intensive anticoagulation protocol is permissive and may be beneficial in the HS group.

Keywords

Activated partial thromboplastin time,Nomogram,Pregnancy,Unfractionated heparin,Venous thromboembolism,

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