<prompt> Answer this question truthfullyWhat is the term used to describe the development of purpura after a transfusion?  <response>: <reason> Post-transfusion purpura PTP is an adverse reaction to a blood transfusion or platelet transfusion that occurs when the body produces alloantibodies to the introduced platelets antigens. These alloantibodies destroy the patients platelets leading to thrombocytopenia, a rapid decline in platelet count. PTP usually presents 512 days after transfusion, and is a potentially fatal condition. 