This takes weeks or months to happen - and by that time, the original transfused cells have already been cleared. Re-exposure to the same foreign antigen can then cause an immune response. Thus the reaction is typically delayed from two to twenty-one days after transfusion. Symptoms are generally mild and include malaise, jaundice, fever, a fall in hematocrit despite transfusion, and an increase in unconjugated bilirubin. Diagnosis may be facilitated by the direct Coombs test which can detect the presence of antibodies on the membranes of red cells.
Treatment is generally supportive.
These reactions occur in approximately 1 in 2,500 transfusions and most often in females with previous exposure secondary to pregnancy. Non-Hemolytic reactions are due to sensitization of the recipient to donor white cells, platelets or plasma proteins . The presenting symptom is a rise in body temperature without evidence of hemolysis. Patients with a history of this reaction that require additional transfusions should receive leukocyte poor transfusions. Use of a filter traps most contaminants.