Use of recombinant human antithrombin concentrate in pregnancy
Patient 2 is a 40-year-old female with a past medical history significant for viral encephalitis and a left leg superficial thrombosis at age 32 while taking oral contraceptive pills. Her oral contraceptive pills were discontinued and she was treated with anti-inflammatory medication. At age 40, patient 2 was 8 weeks pregnant with her third child and sought evaluation for right calf and popliteal pain. She was diagnosed with a non-occlusive deep vein thrombosis of the distal femoral, popliteal, and posterior tibial vein. A hypercoagulable evaluation showed an antithrombin activity of 38%–41%. Her sister, father, and daughter were subsequently diagnosed with antithrombin deficiency but have not experienced thrombosis. Patient 2 was initially treated with enoxaparin at 1.5 mg/kg daily, and was switched to twice daily dosing after the antithrombin deficiency was diagnosed (). At the highest dosage, she required enoxaparin at 1.8 mg/kg twice daily to maintain therapeutic anti-Xa levels. Her pregnancy was otherwise uncomplicated and she was admitted at 37 weeks 4 days gestation for induction of labor. She received a bolus of 41.4 IU/kg and maintenance infusion of 10 IU/kg (calculated as above). Labor induction began once antithrombin levels had normalized. The patient vaginally delivered a healthy male with Apgar scores of 8 and 9 at 1 and 5 minutes, respectively. Estimated blood loss was 300 mL. Her antithrombin levels remained between 96%–127% without adjustment of her infusion (). An unfractionated heparin infusion was started 4 hours after delivery. She was discharged on HD9 on warfarin and twice daily enoxaparin until her INR was >2.0 two days later. She has been maintained on therapeutic anticoagulation due to her history of thrombosis in the setting of antithrombin deficiency.