Use of recombinant human antithrombin concentrate in pregnancy
Patient 1 is a 31-year-old female with a history of unprovoked pulmonary embolism at age 20. Thrombophilia testing was completed due to her young age and a family history of pulmonary embolism in her brother. The patient was found to be AT deficient with an AT activity of 37%. She was maintained on long term anticoagulation with warfarin. Her other past medical history was significant for supraventricular tachycardia, rheumatoid arthritis, endometriosis, pyelonephritis, Crohn’s disease, and gastroesophageal reflux disease. The patient became pregnant in 2010 and was switched to enoxaparin at 4 weeks gestation. Her pregnancy was complicated by gestational diabetes, which was controlled by diet and exercise. Additionally, she had one admission due to supraventricular tachycardia and was found to have irregular uterine contractions. Due to the AT deficiency, anticoagulation was monitored using anti-Xa levels with goal peak level >0.6 IU/mL. At the highest dose, she required enoxaparin 120 units (~1.4 units/kg) subcutaneously every 8 hours ().\nPatient 1 was admitted at 35 weeks and 4 days due to concerns for preterm labor. She was continued on enoxaparin until the evening of hospital day (HD) 2. She started rhAT on HD3 with a loading dose of 48.5 IU/kg (calculated from [100-baseline activity]/1.3) and maintenance dose of 11 IU/kg/hour (calculated from [100-baseline activity]/5.4). She underwent induction of labor via cervical ripening catheter and oxytocin when the AT level was in the normal range. Amniotomy was performed on HD5, and the patient vaginally delivered a healthy infant weighing 2,268 grams on HD6. Apgar scores were 7 and 9 at 1 and 5 minutes, respectively. The estimated blood loss was 250 mL. The rhAT infusion did not require dose modifications and the patient’s AT levels remained between 90%–108% (). Intravenous unfractionated heparin was started immediately postpartum and was adjusted by anti-Xa levels. Additionally, the patient was started on warfarin on the evening of delivery. Admission hemoglobin of the patient was 14.4 g/dL and postpartum hemoglobin was 11.5 g/dL. She was continued on an unfractionated heparin and AT3 infusion until the international normalized ratio (INR) was greater than 2.0 and she was subsequently discharged.