1. Presented by Abi Norwood, MD and reviewed by Lorraine N. Blagg, MA, MLS(ASCP)SBB

Clinical vignette:
A pregnant female with a history of HbSS disease presents with a pain crisis and is voiding dark urine. She was recently hospitalized for a similar pain episode one week prior and received two units RBCs. Her hemoglobin was 7.5 g/dL upon her prior discharge. Now on admission, she is febrile (temperature 39.4?C) and her labs are significant for a hemoglobin 4.7 g/dL, bilirubin 5.5 mg/dL, LDH 1800 U/L, and hemoglobinuria.

The blood bank work-up reveals a delayed hemolytic transfusion reaction due to a newly-identified alloantibody to Go(a), a low prevalence antigen in the Rh system. The patient's anemia is treated with two RBC units that are phenotypically matched, Go(a) negative, Rh negative and her post-transfusion hemoglobin initially improves to 7.5 g/dL. Her hemoglobin trend throughout the remainder of her hospitalization is depicted below.



Question: Which clinical scenario most likely explains the patient's hemoglobin trend?