Purpura, Immune Thrombocytopenic

Rare (100:1 million)

Children: Male > female

Adults: Female > male (2–4:1).

Pregnancy: 1:1000 deliveries; 5% of thrombocytopenia in pregnancy, especially if present in first trimester.

Hemorrhage (case reports put mortality for splenectomy at 1%, one-third of which is related to bleeding).

Infection and thrombocytosis post-splenectomy

Retrospective data from Taiwan point to a higher risk of postop mortality (OR 1.89), complications (1.47), increased length of hospital stay (1.73), and ICU admission (1.89). Preop blood/platelet transfusions are associated with increased risk.

Preop corticosteroids, immunosuppressive agents

Splenectomy

Hemorrhage (mucosal when platelet count is <20,000 × 10 ³ /mm ³ ; severe risk [intracranial hemorrhage] with platelet count <10,000 × 10 ³ /mm ³ ; suggestion that mortality is increased if platelet count is <30,000 × 10 ³ /mm ³ ).

Acute, intermittent, or chronic (12-mo) immune-mediated thrombocytopenia (accelerated destruction with appropriate megakaryocyte response). Recent appreciation of impaired plt production, leading to treatment to stimulate platelet growth. Dermal, mucosal, and CNS hemorrhage is most critical.

Obstetric implications include risk of transient neonatal thrombocytopenia.

Antiplatelet IgG autoantibodies target mature platelets and megakaryocytes, leading to premature removal by spleen and RES. TMO produced in the liver as the principal regulator of megakaryocyte development and platelet production, is suboptimal in ITP pts.