Many different medical conditions require a patient to need a blood transfusion, i.e., when donated blood is given to that individual. In rare cases, a transfusion reaction — when the body's immune system attacks new cells — may result. This adverse reaction usually occurs if the transfused blood is incompatible in some way with the patient's own. Symptoms of a transfusion reaction often begin rapidly and include pain, fever, chills, rash, blood in the urine, and dizziness or fainting; in rare instances, more serious problems occur. Treatments vary depending on the severity of the reaction and are usually focused on dealing with the symptoms.
Occurrences of transfusion reaction are today rare since donated blood is carefully screened and labeled, thereby making it difficult to give a patient the wrong type. In rare cases, a patient can receive blood that is incompatible with his or her own or has an allergic reaction to the new cells. A transfusion reaction happens when the transfused blood contains substances called antigens against which the patient already has antibodies. These antigens can be due to the blood type, the presence or lack of an Rh factor indicated as positive or negative, or other proteins found in the blood. When these antigens come in contact with the patient's immune system, the antibodies that are present initiate an immune response that attacks the new cells because they are seen as a foreign invading pathogens.
The immune response to the transfused blood can cause a range of symptoms which often begin very quickly, but they can be delayed up to several days in some cases. Signs of a transfusion reaction frequently start before the transfusion is complete and require the treatment to be stopped immediately. Symptoms include pain in the side or back, a fever, chills, and dizziness or fainting. Blood can usually be found in the urine and allergic symptoms such as a rash often occur. Depending on the severity of the reaction symptoms, can remain minor; in some cases, however, the patients condition continues to worsen which can result in kidney failure, shock, and anemia.
Treatment for a transfusion reaction usually focuses on the patient's symptoms. Drugs such as acetaminophen can reduce fever and pain, while corticosteroid medications may reduce the immune response. Antihistamines are used to treat the allergic portion of the symptoms such as rash. Intravenous fluids and medications are used to treat more severe symptoms including kidney failure and shock. Mild cases of transfusion reaction can resolve on their own with time, and patients usually make a full recovery from more severe problems with prompt, thorough treatment.