February 2022 – Transfusion Medicine

A 56-year-old man with a past medical history of acute myeloid leukemia with chemotherapy-induced pancytopenia presents to Station 94 at Mayo Clinic to receive one unit of RBCs due to anemia (pre-transfusion Hb is 6.0). 320/330 mL of the transfusion was in when the patient developed itching hives on the chest, abdomen, and right arm. He also endorsed mild facial edema and hoarseness. The transfusion was subsequently stopped, the patient given IV Benadryl with symptom resolution, and the blood bank was notified and performed their transfusion reaction investigation, which showed satisfactory clerical check, no pre- or post-specimen hemolysis, and a negative DAT. 

What is the most likely diagnosis of this transfusion reaction?

  • Mildly severe allergic reaction.
  • Transfusion-associated dyspnea.
  • Moderately severe allergic reaction.
  • Transfusion-associated circulatory overload.

The correct answer is ...

Moderately severe allergic reaction.


  1. Harmening, Denise M. (2019). Modern Blood Banking and Transfusion Practices
  2. Gil, Morayma Reyes, et al. Transfusion Medicine and Hemostasis: Clinical and Laboratory Aspects. Elsevier Science, 2019.
  3. “National Healthcare Safety Network Biovigilance Component Hemovigilance Module Surveillance Protocol” by Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA

Phuong-Lan Nguyen, M.D.

Fellow, Hematopathology
Mayo Clinic

Photo of Dr. Justin Kreuter

Justin Kreuter, M.D.

Consultant, Transfusion Medicine
Mayo Clinic
Assistant Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science

MCL Education

This post was developed by our Education and Technical Publications Team.