Posttransfusion purpura

This code signifies a rare, severe thrombocytopenia that develops approximately 5-10 days after a blood transfusion. It is characterized by the sudden destruction of the patient's own platelets, often due to alloantibodies formed in response to transfused platelet antigens. Patients typically present with widespread purpura and other bleeding manifestations.

Assign this code when documentation explicitly states a diagnosis of posttransfusion purpura following a recent blood product transfusion. Supporting documentation should include evidence of severe thrombocytopenia and a clear temporal relationship to the transfusion event. This diagnosis is typically made after excluding other causes of post-transfusion thrombocytopenia.

• Ensure documentation specifies "purpura" and not just general post-transfusion thrombocytopenia, which may have different underlying causes.
• Always sequence this code as the principal diagnosis if it is the primary reason for the encounter, followed by codes for any associated bleeding manifestations.
• Do not confuse with other transfusion reactions or drug-induced thrombocytopenia; the specific diagnosis of posttransfusion purpura is key.