A 50-year-old multiparous woman with a past medical history of systemic lupus erythematosus and antiphospholipid syndrome (on anticoagulation with warfarin) was admitted to the hospital for management of spontaneous retroperitoneal bleeding in the setting of an elevated prothombin time (INR=4.4). One unit of packed red blood cells and six units of fresh frozen plasma were administered on admission. The patient's INR normalized, and the retroperitoneal bleeding stabilized. On hospital day 6, an acute decline in the patient's platelet count was noted (see Figure 1). Serum heparin-platelet factor 4 antibody test was negative, but a serum-platelet antibody test was positive for glycoprotein IIb/IIIa antibodies (with likely specificity for human-platelet antigen 1a [HPA-1a]).
The patient was diagnosed with post-transfusion purpura. Her platelet count slowly returned to baseline after intravenous immunoglobulin (IVIG) therapy.
Andrew Norgan, M.D., Ph.D.
Resident, Clinical Pathology
Jeffrey Winters, M.D.
Consultant, Division of Transfusion Medicine
Professor of Laboratory Medicine and Pathology,
Mayo Clinic College of Medicine