Initial Assessment And Stabilization

• Stabilize child before diagnostic workup.
• Assess disorder severity and magnitude of blood loss.
• Administer adequate replacement fluids and blood products.
• Initiate component therapy if hemodynamically unstable.

Clinical Evaluation

Detailed History

• Age of onset: Neonatal presentation suggests severe congenital defects; later onset suggests acquired or mild congenital defects.
• Site of bleeding: Differentiates primary (platelet/vascular) from secondary (coagulation) hemostasis defects.
• Provoked versus spontaneous: Spontaneous bleeding implies severe defect. Note bleeding after circumcision, heel stick, or immunizations.
• Antecedent events: Recent viral infections, rashes (IgA vasculitis, varicella), jaundice, or diarrhea (hemolytic uremic syndrome).
• Medication history: Anticonvulsants, penicillins, warfarin, aspirin, non-steroidal anti-inflammatory medications, heparin.
• Family history: Identify sex of affected members, specific bleeding manifestations, consanguinity.

Clinical Features Suggestive Of Pathologic Bleeding

• Umbilical stump bleeding (suggests factor XIII deficiency).
• Intracranial hemorrhage in neonates.
• Excessive bleeding post-circumcision or heel stick.
• Palpable bruises in non-mobile infants.
• Hematomas, hemarthroses, retroperitoneal bleeding.
• Menorrhagia: Bleeding >7 days, >80 mL loss, soaking pads within 1 hour.
• Traumatic bleeding out of proportion to injury (rule out nonaccidental trauma).

Physical Examination

• Degree of anemia: Assess pallor, tachycardia, hemodynamics.
• Skin manifestations: Fading versus new ecchymoses, petechiae, purpura.
• Vascular lesions: Hemangiomas, telangiectasias (Kasabach-Merritt syndrome, hereditary hemorrhagic telangiectasia).
• Organomegaly: Splenomegaly suggests infection, malignancy, hypersplenism, collagen vascular disorders.
• Joint mobility: Assess Beighton score (maximum 9 points; score >5 indicates hypermobility, suggests Ehlers-Danlos syndrome).
• Syndromic stigmata: Evaluate for congenital bone marrow failure syndromes (Fanconi anemia, thrombocytopenia with absent radii).

Diagnostic Algorithm

Interpretation Of Screening Tests

Advanced Coagulation Laboratory Assessment

Mixing Studies

• Differentiates factor deficiency from acquired circulating inhibitors.
• Normal plasma added to patient plasma (1:1 ratio).
• Complete correction indicates clotting factor deficiency.
• Failure to correct or partial correction indicates coagulation inhibitor (e.g., specific factor antibody, lupus anticoagulant).

Thrombin Time And Reptilase Time

• Thrombin Time (TT): Measures final conversion of fibrinogen to fibrin. Prolonged by hypofibrinogenemia, dysfibrinogenemia, heparin, or elevated fibrin degradation products.
• Reptilase Time: Utilizes snake venom to clot fibrinogen. Unaffected by heparin. Differentiates heparin contamination (prolonged TT, normal reptilase) from true fibrinogen defects (prolonged TT and reptilase time).

Specific Factor Assays

• Quantify precise functional activity of individual clotting proteins.
• Indicated when mixing studies normalize specific pathway abnormalities.
• Essential for classifying severity of hemophilias (Severe <1%, Moderate 1-5%, Mild 5-40%).

Von Willebrand Disease Panel

• vWF Antigen (vWF:Ag): Quantifies total vWF protein concentration.
• Ristocetin Cofactor Activity (vWF:RCo): Assesses functional interaction between vWF and platelets.
• Factor VIII Activity: Often reduced due to absent vWF chaperone function.
• vWF Multimer Analysis: Visualizes molecular weight multimers. Identifies absence of high-molecular-weight multimers in Types 2A and 2B.

Global Hemostatic Tests

• Thromboelastography (TEG): Assesses viscoelastic properties of whole blood clot formation under low shear.
• Evaluates clot initiation (R time), kinetics (K time, alpha angle), strength (Maximum Amplitude), and fibrinolysis.
• Thrombin Generation Assay: Fluorogenic substrate continuously measures endogenous thrombin potential.

Differential Diagnosis By Etiology

Platelet Disorders

• Manifest with mucocutaneous bleeding: epistaxis, petechiae, superficial ecchymoses, mucosal oozing.
• Hemarthrosis extremely rare.

Quantitative Disorders (Thrombocytopenia)

• Immune Destruction: Immune thrombocytopenic purpura (ITP), drug-induced, Evans syndrome, neonatal alloimmune thrombocytopenia (NAIT).
• Consumption: Hemolytic uremic syndrome (HUS), thrombotic thrombocytopenic purpura (TTP), disseminated intravascular coagulation (DIC), Kasabach-Merritt syndrome.
• Decreased Production: Congenital amegakaryocytic thrombocytopenia (CAMT), thrombocytopenia-absent radius (TAR) syndrome, aplastic anemia, marrow infiltration.
• Sequestration: Hypersplenism from portal hypertension, Gaucher disease.

Qualitative Disorders (Platelet Dysfunction)

• Bernard-Soulier Syndrome: Autosomal recessive. Absence of glycoprotein Ib-IX-V complex (vWF receptor). Macrothrombocytopenia. Absent ristocetin-induced aggregation.
• Glanzmann Thrombasthenia: Autosomal recessive. Deficiency of glycoprotein IIb/IIIa complex (fibrinogen receptor). Normal platelet count/morphology. Absent aggregation to all agonists except ristocetin.
• Storage Pool Deficiencies: Gray platelet syndrome (alpha granule deficiency). Hermansky-Pudlak syndrome (dense granule deficiency, oculocutaneous albinism).
• Acquired Dysfunction: Uremia, advanced liver disease, cardiopulmonary bypass, medication effects (aspirin, NSAIDs).

Coagulation Factor Deficiencies

• Manifest with deep tissue bleeding: hemarthroses, large intramuscular hematomas, delayed surgical bleeding.

Hemophilia A And B

• Genetics: X-linked recessive. Hemophilia A (Factor VIII deficiency); Hemophilia B (Factor IX deficiency).
• Laboratory: Prolonged aPTT, normal PT, normal platelet count. Specific factor assays establish definitive diagnosis.
• Clinical: Severe disease (<1% factor) causes spontaneous joint and muscle bleeds. Target joints develop from recurrent hemarthroses.
• Treatment: Specific recombinant factor concentrates. Prophylaxis recommended for severe phenotypes to prevent arthropathy.

Von Willebrand Disease

• Genetics: Most common inherited bleeding disorder. Mostly autosomal dominant.
• Pathophysiology: Deficient or defective vWF impairs platelet adhesion and factor VIII protection.
• Classification:
  • Type 1: Partial quantitative deficiency.
  • Type 2: Qualitative functional defects (Subtypes 2A, 2B, 2M, 2N).
  • Type 3: Complete quantitative absence.
• Treatment: Desmopressin (DDAVP) for Type 1. vWF-containing factor concentrates for severe types or unresponsiveness. Antifibrinolytics for mucosal bleeding.

Disseminated Intravascular Coagulation (DIC)

• Acquired clinicopathologic syndrome.
• Triggers include sepsis, trauma, malignancy, massive tissue injury.
• Pathogenesis involves unregulated thrombin generation, widespread microvascular fibrin deposition, and consumption of platelets/coagulation factors.
• Secondary hyperfibrinolysis generates fibrin degradation products.
• Laboratory: Prolonged PT/aPTT, hypofibrinogenemia, thrombocytopenia, elevated D-dimers/FDPs, microangiopathic hemolytic anemia (schistocytes).
• Management: Treat underlying trigger. Replace depleted components (fresh frozen plasma, cryoprecipitate, platelets) only for active hemorrhage or invasive procedures.

Vitamin K Deficiency

• Required for gamma-carboxylation of factors II, VII, IX, X, Protein C, Protein S.
• Prolongs PT early (factor VII has shortest half-life), followed by aPTT.
• Responsive to parenteral vitamin K administration.

Liver Disease Coagulopathy

• Liver synthesizes most procoagulant and natural anticoagulant proteins.
• Promotes complex hemostatic imbalance.
• Laboratory: Prolonged PT/aPTT, thrombocytopenia (hypersplenism/decreased thrombopoietin), dysfibrinogenemia.
• Factor VIII remains normal or elevated (synthesized in endothelial cells), distinguishing liver failure from DIC.
• Decreased natural anticoagulants (Protein C, S, Antithrombin) and hyperfibrinolysis.

Vascular And Connective Tissue Disorders

• Bleeding caused by fragility of skin, subcutaneous tissues, and vessel walls.
• Coagulation studies usually normal.
• Ehlers-Danlos Syndrome: Vascular type (Type IV) involves defect in type III collagen. Prone to arterial rupture, sudden death, easy bruising.
• Hereditary Hemorrhagic Telangiectasia: Autosomal dominant. Arteriovenous malformations in mucocutaneous and visceral surfaces. Recurrent epistaxis.

Management Principles

General Hemostatic Interventions

• Apply direct pressure, pack wounds, immobilize joints.
• Antifibrinolytic agents (aminocaproic acid, tranexamic acid) stabilize mucosal clots (contraindicated with prothrombin complex concentrates).
• Desmopressin (DDAVP) induces endothelial release of vWF and FVIII. Useful for mild Hemophilia A, Type 1 vWD, and mild platelet dysfunctions.

Component Replacement Therapy