Excessive Bleeding in Aplastic Anemia: The Central Role of Thrombocytopenia

Aplastic anemia (AA) is pancytopenia (low RBCs, WBCs, platelets) from bone marrow failure. Bleeding is driven primarily by severe thrombocytopenia (platelets <10–20 × 10⁹/L), not anemia.

Platelet Physiology & Hemostasis Failure

1. Primary hemostasis: Platelets adhere (vWF-GPIb), activate, aggregate (GPIIb/IIIa-fibrinogen) → platelet plug.
2. Secondary hemostasis: Coagulation cascade → fibrin mesh stabilizes plug.
3. In AA: Quantitative platelet deficiency → failed primary hemostasis → mucosal/skin bleeding (petechiae, ecchymoses, epistaxis, gingival, menorrhagia).
4. Coagulation factors (liver-made) are usually normal — PT/INR, aPTT normal unless DIC or liver disease coexists.

Bleeding Manifestations

• Petechiae (pinpoint, non-blanching) — dependent areas
• Epistaxis, gingival bleeding
• Menorrhagia
• Retinal hemorrhages (vision threat)
• Intracranial hemorrhage (rare but fatal; platelets <10–20k)
• Prolonged bleeding from minor cuts, procedures

Management

• Platelet transfusion: Prophylactic <10k; therapeutic for active bleeding/fever/procedures. HLA-matched/refractory protocols if alloimmunized.
• Definitive therapy: IST (ATG + CsA) or HSCT (curative).
• Supportive: Antifibrinolytics (tranexamic acid) for mucosal bleeding; avoid NSAIDs/antiplatelets; soft toothbrush; stool softeners.
• Infection prophylaxis: Neutropenia → bacterial/fungal prophylaxis.

Key Distinction

Anemia causes fatigue, dyspnea, tachycardia. Thrombocytopenia causes bleeding. Both stem from marrow failure but require separate monitoring and transfusion triggers.