Delayed Hemolytic Transfusion Reaction With Acute Kidney Injury Due to Anti-E Antibody in a 43-Year-Old Woman With Iron-Deficiency Anemia.

Delayed hemolytic transfusion reactions (DHTRs) are uncommon yet serious complications of blood transfusion and are often underdiagnosed in patients with negative pre-transfusion antibody screens and a negative direct antiglobulin test (DAT). We report a case of a 43-year-old woman with iron-deficiency anemia secondary to menorrhagia who developed a DHTR with acute kidney injury following red blood cell transfusion. Despite a negative pre-transfusion antibody screen and DAT, she developed hemolysis and renal dysfunction approximately one week post-transfusion; the reference laboratory later identified anti-E antibodies. This case highlights the diagnostic challenges of DHTRs when pre-transfusion serology and DAT are negative. Vigilant clinical suspicion and post-transfusion monitoring are crucial to prevent and manage potentially life-threatening complications.