Delayed hemolytic transfusion reaction (DHTR) is a potentially serious complication of blood transfusions that can occur days or weeks after the transfusion. It is caused by an immune reaction against the donor's red blood cells, resulting in anemia and hemolysis (the destruction of red blood cells).
Causes of DHTR
DHTR is the result of an immune response to antigens present on the donor's red blood cells. This reaction can occur when the donor and recipient have different blood types, or if the recipient has pre-existing antibodies to antigens present on the donor's blood cells.
The most common cause of DHTR is ABO incompatibility, where the donor has a different blood type than the recipient. Other potential causes include Rh incompatibility, an Rh antigen mismatch, or the presence of antibodies in the recipient's blood to antigens found on the donor's red blood cells.
Risk Factors for DHTR
The risk of DHTR increases with the number of transfusions the recipient has received. The risk is also increased in patients who have received multiple blood transfusions in the past, or those with a history of previous transfusion reactions.
Signs and Symptoms of DHTR
The signs and symptoms of DHTR can vary depending on the severity of the reaction. The most common symptoms include fever, chills, back pain, nausea, vomiting, and dark urine. Other symptoms can include jaundice (yellowing of the skin and eyes), abdominal pain, and fatigue.
Diagnosis of DHTR
DHTR is typically diagnosed through a combination of clinical and laboratory tests. A complete blood count (CBC) can help detect anemia and hemolysis, while a serologic assay can help identify antibodies in the recipient's blood that are reactive to donor antigens.
Treatment of DHTR
Treatment of DHTR typically involves supportive care and the removal of the donor blood. This may include intravenous fluids to replace lost fluids, and medications to reduce fever and other symptoms. In severe cases, a platelet transfusion may be necessary to help prevent further hemolysis.
Prevention of DHTR
The best way to prevent DHTR is to carefully match the donor and recipient's blood types prior to transfusion. In addition, screening for pre-existing antibodies can help identify patients at risk of DHTR. Finally, it is important to ensure that the donor's blood is free of any infectious agents that could potentially cause a reaction.
