Spontaneous hemarthrosis due to coagulopathy

Specialty: Hematology.

• Spontaneous intra-articular bleeding
• joint hemorrhage due to factor deficiency
• hemorrhagic joint effusion

Why it occurs

• Hemophilia A (congenital recessive X-linked deficiency of coagulation factor VIII, which severely alters the intrinsic pathway and thrombin generation)
• Hemophilia B (congenital recessive deficiency of coagulation factor IX, with identical clinical presentation of bleeding in weight-bearing joints)
• Acquired hemophilia (development of autoantibodies directed against factor VIII, frequently associated with autoimmune diseases, neoplasms or the postpartum period)
• Severe deficiency of coagulation factor X, V or II (rare congenital coagulopathies of autosomal recessive inheritance)
• Supratherapeutic anticoagulant treatment (overdose of vitamin K antagonists such as warfarin or acenocoumarol, or new oral anticoagulants that are direct inhibitors of factor Xa or thrombin).

Initial workup

Basic coagulation times, including prothrombin time (PT) and, crucially, activated partial thromboplastin time (aPTT), which is prolonged in isolation in hemophilias; 1:1 aPTT mixture test with normal plasma to differentiate between factor deficiency (aPTT corrects after mixing) and the presence of a circulating inhibitor (aPTT does not correct); specific quantification of the functional activity of factors VIII, IX and XI; high-resolution joint ultrasound or magnetic resonance imaging of the affected joint to delineate the volume of bleeding, rule out chronic hypertrophic synovitis, and evaluate articular cartilage damage (hemophilic arthropathy); complete blood count to monitor secondary decrease in hemoglobin values.

Standard management

• Factor VIII concentrate of plasma or recombinant origin — urgent intravenous infusion when suspected hemarthrosis in Hemophilia A; dose calculated to raise the factor level to 40-50% of the normal range in mild-moderate bleeding, or to 80-100% in severe life-threatening or compartmental bleeding
• Coagulation Factor IX concentrate — indicated in Hemophilia B; requires higher doses due to its broader tissue volume of distribution
• Emicizumab — bispecific monoclonal antibody that mimics the function of activated factor VIII by binding factors IXa and X; used as subcutaneous prophylaxis of choice in patients with Hemophilia A with or without inhibitors
• Tranexamic acid (oral or intravenous antifibrinolytic that competitively inhibits plasminogen activation; useful as adjuvant therapy to stabilize the clot, contraindicated in the presence of hematuria due to the risk of ureteral obstruction).