Anticoagulant management in an antithrombin-deficient pregnant woman with a history of venous thromboembolism

Background: Antithrombin deficiency (ATD) in pregnant patients significantly increases the risk of venous thromboembolism (VTE), but guidelines for managing anticoagulation during pregnancy, labour, and postpartum in patients with ATD are limited. Case presentation: A pregnant woman with ATD suffered recurrent VTE in the 20th week of pregnancy despite therapeutic doses of low-molecular-weight heparin (LMWH). The acute VTE was treated with argatroban and then with warfarin until delivery. LMWH with antithrombin (AT) concentrate was introduced before and shortly after delivery, followed by warfarin, which was continued also postpartum. No further complications occurred during the remainder of pregnancy, delivery, and two-year follow-up. Conclusion: Our case highlights the challenges of anticoagulant treatment in pregnant patients with ATD. Standard weight-based LMWH dosing can lead to inadequate anticoagulation, as demonstrated by an acute VTE event in our patient. In our case, the use of argatroban proved to be safe and effective in the acute setting, followed by warfarin in the 2nd and 3rd trimester, and subsequent co-administration of LMWH and AT concentrate before and after delivery. Concomitant use of LMWH and AT concentrate allows for achieving target anti-Xa levels. Measurement of both anti-Xa and AT activity is advisable in this scenario to ensure reliable anticoagulant management. ATD is a heterogeneous disorder