Post-Transfusion Purpura (PTP) typically occurs in which patients?

• A. Multiparous women or patients previously transfused
• B. Neonates receiving maternal antibodies
• C. Individuals with iron overload
• D. Patients with active infection

Answer: (A)

Post-transfusion purpura happens when someone has already been sensitized to platelet antigens, usually from prior pregnancies or previous transfusions. The immune system makes alloantibodies against specific platelet antigens, and after a subsequent transfusion these antibodies rapidly attack the donor platelets, leading to severe thrombocytopenia and purpura. This pattern—sensitization from past pregnancies or transfusions followed by a new transfusion causing platelet destruction—makes multiparous women or patients with prior transfusions the typical affected groups. Neonatal alloimmune thrombocytopenia involves maternal antibodies affecting the fetus, not the recipient after a transfusion. Iron overload or active infection don’t explain this alloimmune platelet destruction after transfusion.