Clinical Presentation - Delayed Hemolytic Transfusion Reactions

DHTR may go undetected as the symptoms may be mild and subclinical. Death is a rare event but has been reported. Red cell destruction is usually by extravascular hemolysis (EVH). When present, typical signs and symptoms include:

• fever with or without chills
• unexplained drop in hemoglobin and hematocrit
• transient jaundice due to elevated serum bilirubin

Mechanism

Upon re-stimulation by red cells positive for the corresponding antigen to the patient's weak, undetectable alloantibody, memory B cells differentiate into antibody-producing plasma cells. As new IgG antibody is produced, it sensitizes transfused donor cells with the corresponding antigen. The IgG-sensitized donor cells are removed by EVH mainly in the spleen.