In simple words: Post-transfusion purpura (PTP) is a rare reaction to a blood or platelet transfusion where the body's immune system attacks its own platelets. This usually happens about a week after the transfusion and causes a low platelet count, which can lead to bleeding problems.

Post-transfusion purpura (PTP) is a rare but serious immune-mediated adverse reaction that occurs after a blood or platelet transfusion.It typically develops 7-10 days post-transfusion and is characterized by a sudden and severe drop in platelet count (thrombocytopenia), which can lead to bleeding. PTP is most commonly seen in women with a history of multiple pregnancies or previous transfusions, and it occurs due to the formation of antibodies, often against the human platelet antigen HPA-1a, leading to platelet destruction.

Example 1: A 45-year-old woman with a history of multiple pregnancies develops severe thrombocytopenia and bleeding one week after receiving a blood transfusion., A 60-year-old man who has received multiple transfusions in the past experiences sudden onset of bruising and petechiae 10 days after a platelet transfusion. , A 30-year-old woman develops PTP after her first blood transfusion, later testing positive for antibodies against HPA-1a.

Documentation should include transfusion history, date of transfusion, onset of symptoms, platelet counts, results of antiplatelet antibody testing, and treatment provided.