Personalized anticoagulation and drug monitoring for pregnancy-associated venous thromboembolism in hereditary type IIa antithrombin deficiency

Pregnant women with hereditary type IIa antithrombin deficiency (ATD) are at significantly increased thrombotic risk. We present the case of a woman with four consecutive pregnancy losses due to venous thromboembolism (VTE), subsequently diagnosed with type IIa hereditary ATD. Type IIa ATD is exceptionally rare. The principal therapeutic challenge lies in the absence of established guidelines regarding optimal anticoagulant selection, dosing strategies, and monitoring approaches for such patients, contributing to treatment failure in her first four pregnancies. The patient was referred to our institution before her fifth conception. Preconception intervention began, and we instituted low-molecular-weight heparin (LMWH) therapy, with dose titration guided by thrombin-antithrombin complex (TAT) and anti-Xa activity levels. This regimen demonstrated safety and efficacy, achieving a maximum nadroparin dose of 10 250 IU twice daily. Under close pharmacotherapeutic monitoring by a clinical pharmacist using this individualized protocol, the patient achieved a successful term delivery and was discharged.