When Blood Is Being Difficult: Clotting and Bleeding in a Patient With Antiphospholipid Antibody Syndrome and Supratherapeutic International Normalized Ratio

Venous thromboembolism includes deep venous thrombosis (DVT) and pulmonary embolism and is the most common cardiovascular disease after coronary artery disease and stroke. Antiphospholipid syndrome (APS) is an autoimmune disorder that is characterized by venous or arterial thrombosis with laboratory evidence of antiphospholipid antibodies. Long-term anticoagulation therapy is required to prevent recurrent DVTs, embolisms, and thrombosis-related complications. Treatment options include vitamin K antagonists, subcutaneous low-molecular-weight heparin, unfractionated heparin, or direct oral anticoagulants. Warfarin (a vitamin K antagonist) remains the mainstay of treatment in APS patients with a prior history of DVT and is associated with elevation of the international normalized ratio which is often used as a marker for therapy appropriateness and warfarin dosing. Here, we describe a unique case of a 65-year-old female with APS on warfarin (given prior lower extremity DVT) presenting with bleeding/hematoma in the left breast and a clot in the left upper extremity.