ACS :: Possible Risks of Blood Product Transfusions

Although blood transfusions can be life-saving, they are not without risks. The most serious risks are transfusion reactions and infections.

Blood product transfusions sometimes cause transfusion reactions. There are several types of reactions and some are worse than others. Some reactions happen as soon as the transfusion is started, while others take several days or even longer to develop.

Many precautions are taken before a transfusion is started to keep reactions from happening. The blood type of the unit is checked many times, and the unit is cross-matched to be sure that it matches the blood type of the person who will receive it. After that, a nurse and blood bank lab technician look together at the information about the patient and the information on the unit of blood (or blood component) before it is released. The information is double-checked once more in the patient's presence before the transfusion is started.

Allergic reaction: This is the most common type of reaction. It happens during the transfusion because of the body's reaction to plasma proteins in the donated blood. Usually the only symptoms are hives and itching, which can be treated with antihistamines such as diphenhydramine (Benadryl). In rare cases these reactions can be more serious.

Febrile reaction: Febrile transfusion reactions mean that a person gets a sudden fever during or within 24 hours of the transfusion. Headache, nausea, chills, or a general feeling of discomfort may come with the fever. Acetaminophen (Tylenol^®) may help these symptoms. These reactions are a response by the body to white blood cells in the donated blood. They are more common in people who have had transfusions before and in women who have had several pregnancies. Other types of reaction can also cause fever, and further testing may be needed to be sure that the reaction is only a febrile one.

Patients who have had febrile reactions or who are at risk for them are usually given blood products that are leukoreduced. This means that the white blood cells have been removed by filters or other means.

Transfusion-related acute lung injury (TRALI): This is a very serious transfusion reaction, which happens in about 1 out of every 5,000 transfusions. It can happen with any type of transfusion, but those that contain more plasma, such as FFP or platelets, seem more likely to cause the problem. It often starts within 1 to 2 hours of starting the transfusion, but can happen anytime up to 6 hours after a transfusion. More recently, a delayed TRALI syndrome has been recognized, which can begin up to 72 hours after transfusion is given. The main symptom a patient will feel is trouble breathing. If TRALI is suspected the transfusion should be stopped right away.

Doctors now believe that there are several factors involved in this illness, and medicines don’t seem to help. Many of the patients who get TRALI have had recent surgery, trauma, cancer treatment, transfusion, or have an active infection. Most of the time TRALI goes away within 2 or 3 days if the breathing and blood pressure are supported, but even with support it can cause death in 5% to 10% of cases. Delayed TRALI has a higher risk of death, with one expert finding a death rate up to 40%. TRALI is more likely to be fatal if the patient was already very ill before the transfusion. Most often a patient will need oxygen, fluids, and sometimes support with a breathing machine.

If a patient who has had TRALI needs blood, doctors may try to prevent future problems by "washing" the red cells in a dilute salt water solution to remove most of the plasma while saving the red blood cells. Researchers are working on ways to reduce this risk with donor selection and testing.

Acute immune hemolytic reaction: This is the most serious type of transfusion reaction, but it is very rare. It happens when donor and patient blood types do not match. The patient's antibodies attack the transfused red blood cells, causing them to break open (hemolyze) and release harmful substances into the bloodstream. Patients may have chills, fever, chest and lower back pain, and nausea. The kidneys may be badly damaged, and dialysis may be needed. A hemolytic reaction can cause death if the transfusion is not stopped as soon as the reaction starts.

Delayed hemolytic reaction: This type of reaction happens when the body slowly attacks antigens (other than ABO antigens) on the transfused blood cells. The blood cells break down days or weeks after transfusion. There are usually no symptoms, but the transfused red blood cells are destroyed and the patient's red blood cell count falls. In rare cases the kidneys may be affected, requiring treatment.

People don't usually have these types of reactions unless they have had several transfusions in the past. People who have this type of reaction need special blood testing before any more blood can be transfused. Units of blood that do not have the antigen that the body is attacking must be used.

Graft-versus-host disease (GVHD): GVHD occurs when a person with a severely weakened immune system gets white blood cells in transfused blood, and the white cells attack the tissues of the person who got the blood. It is more likely to happen if the person getting the blood is a relative or has a similar tissue type to the donor. The recipient's immune system doesn't recognize the white blood cells in the transfused blood as foreign. This allows them to survive and attack the recipient's body tissues. Within a month of the transfusion, the patient may have fever, liver problems, rash, and diarrhea. To prevent white blood cells from causing GVHD, donated blood can be treated with radiation before transfusion. Radiation stops white blood cells from working but does not affect red blood cells.

Blood transfusions can transmit infections caused by bacteria, viruses, and parasites. The chance of getting an infection from blood in the United States. is extremely low, but the exact risk for each type of infection varies. Testing units of blood for signs of germs that can cause infections has made the blood supply very safe, but no test is 100% accurate.

Bacterial contamination: Rarely, blood gets contaminated with tiny amounts of skin bacteria during donation. Platelets are the most likely blood component to have this problem. Because platelets must be stored at room temperature, these bacteria can grow rapidly. This affects about 1 in 1000 to 3000 units of platelets that are donated. Patients who get these platelets may develop serious illness within minutes or hours after the transfusion is started. In 2004, blood banks started testing platelets before they are given, so that they can throw out affected units and lower the risk of illness. These tests are still being refined, but there are fewer cases of illness resulting from the platelets. There are also more hospitals that use apheresis platelets, which have a lower risk of bacterial contamination than pooled platelets.

Hepatitis B and C: Viruses that attack the liver cause these forms of hepatitis. Hepatitis is the most common disease transmitted by blood transfusions. According to the American Red Cross, about 1 blood transfusion in 205,000 transmits a hepatitis B infection, and 1 blood transfusion in about 2 million may transmit hepatitis C. A 2009 study on hepatitis B in donated blood suggests that the risk is actually lower than this, and work continues to reduce the risk of these infections even further. In most cases there are no symptoms, but hepatitis can sometimes lead to liver failure and other problems.

Several steps are routinely taken to reduce the risk of hepatitis from blood transfusion. People who are getting ready to donate blood are asked questions about hepatitis risk factors and symptoms of hepatitis. Donated blood is also tested to find hepatitis B virus, hepatitis C virus, and liver problems that might point to other types of hepatitis.

Human immunodeficiency virus (HIV): HIV causes acquired immune deficiency syndrome (AIDS). Testing each unit of donated blood for HIV began in 1985, and tests for HIV are now used on all donated blood. With improved testing for HIV, the number of transfusion-related AIDS cases continues to drop. The risk of HIV transmission from a transfusion is about now about one in 2,135,000. Along with testing, the risk is reduced by asking donors questions about HIV risk factors and symptoms.

Other infections tested for: Along with the tests noted above, all blood for transfusion is tested for syphilis, as well as HTLV-I and HTLV-II (viruses linked to human T-cell leukemia/lymphoma). Since 2003, donated blood has been tested for the West Nile virus too.

Other possible infections: Diseases caused by certain bacteria, viruses, and parasites, such as babesiosis, Chagas disease, malaria, Lyme disease, and others can also be spread by blood product transfusions. But because potential donors are screened with questions about their health status and travel, such cases are very rare.

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