Blood transfusion using cells donated by healthy volunteers can help replace red cells, platelets and other blood components. Some people with leukemia, lymphoma, myeloma and other blood diseases or disorders such as hereditary anemias and aplastic anemia need periodic blood transfusions for several reasons:
- The disease process itself can sometimes interfere with the normal production of red cells, white cells and platelets in the bone marrow. For example, almost all patients with leukemia (which primarily affects the marrow and blood) require some transfusions during their care.
- Many chemotherapy drugs can temporarily impair blood cell production in the marrow and depress immune system functions.
- Stem cell transplantation patients receive high doses of chemotherapy, which depletes stores of normal blood cells.
Patients with insufficient blood counts can develop:
- Anemia (low red cells)
- Thrombocytopenia (low platelets)
- Leukopenia (low white cells, either granulocytes or lymphocytes, or both)
Doctors take different approaches when deciding if transfusion is appropriate. How to best balance the benefits and risks of transfusions is the subject of some debate in the medical field. Currently, transfusion policies usually depend on the patient's condition, an individual doctor's training and experience and long-held medical standards of practice.
When you receive a transfusion, you won't be getting whole blood. Instead, you'll receive components of blood that has been filtered. The whole blood is collected from the donor and sent to a lab for separation, allowing one donation to benefit up to four patients and conserving precious blood resources.
Another process that separates some blood components is called apheresis or hemapheresis. This involves removing certain components from a donor's blood and returning the unneeded parts to the donor.
Components that you can receive separately by transfusion are:
- Red cells
- Granulocytes (white cells)
- Plasma and cryoprecipitate
- Gamma globulin
A rare but potentially life-threatening complication of transfusion is graft versus host disease, which occurs when a donor's white cells attack the recipient's immune system. To prevent this, some centres irradiate (treat with radiation) blood components for patients receiving intensive chemotherapy, undergoing stem cell transplant or who are considered to have impaired immune system. Irradiation prevents white cells from attacking.
Red Cell Transfusion
Low red cell counts (anemia), if untreated, can cause weakness, fatigue and, in extreme cases, shortness of breath or rapid heartbeat. Most doctors prescribe red cell transfusions before a patient develops serious symptoms, particularly when managing older patients or those who have a history of heart or blood vessel disease. Blood donated to patients with blood diseases should always have the white cells removed by filtration, a process called leukoreduced or leukodepleted. Leukoreduction reduces the risks of:
- Fever and chills after transfusion
- Not responding to platelet transfusions
- Transmission of some viral infections such as cytomegalovirus and HTLV-1
If you receive ongoing red cell transfusions, you're at risk of developing iron overload, which, if not treated, can damage your heart and liver. You may need treatment with a drug called an iron chelator to remove excess iron from your body.
Platelet transfusions are given to prevent or treat bleeding because of severely low platelet counts (thrombocytopenia). Maintaining a platelet count of more than 5,000 per microliter (µL) of blood, and sometimes higher, seems to reduce risk of:
- Minor bleeding, such as nose bleeds
- Bruises in the skin (ecchymoses)
- Pinhead-sized red spots under the skin caused by bleeding (petechiae)
Not all doctors agree about the appropriate platelet counts that should signal the start of preventive (prophylactic) transfusions, therefore platelet transfusion decisions vary greatly among hematologists and oncologists.
Donated platelet units should have the white cells removed by filtration before transfusion, and if appropriate, they should be irradiated as well.
Granulocytes are a type of white cell. If you have few or no circulating white cells, you can develop an infection that doesn't respond to antibiotics. Therefore, your doctor may give you granulocyte transfusions, which can provide some benefit until your own white cell counts recover. The cells should be irradiated before transfusion but not treated with leukoreduction filters. Since there's uncertainty over whether current methods of granulocyte collection produce an effective transfusion, granulocyte donors are sometimes given a granulocyte colony-stimulating factor (G-CSF) to increase their white cell production.
Plasma and Cryoprecipitate Transfusion
Fresh frozen plasma (FFP), the fluid that carries blood cells, and cryoprecipitate, the portion of the plasma that contains clotting factors (often called cryo for short), may be transfused to patients whose blood has abnormal or low levels of blood-clotting proteins. Problems can develop in patients as a result of liver disease or infection. Fortunately, these conditions are uncommon in most people with blood cancers, except for people with promyelocytic leukemia, who may need transfusions to prevent or treat bleeding.
Intravenous Gamma Globulin
Gamma globulins are portions of proteins in plasma that play a key role in preventing infection. Severely low levels of gamma globulin can lead to an increased risk of some types of bacterial infections. Very low gamma globulins are common to chronic lymphocytic leukemia. Your doctor may want to increase low gamma globulin:
- If you're undergoing a stem cell transplant
- To reduce your risk of cytomegalovirus, its immune complications or its treatment
Albumin is the most common human blood protein. Rarely, transfusion of albumin is needed in patients suffering from severe liver malfunction.
Blood Transfusion Safety
Every patient and doctor is concerned about blood supply safety. The good news is that the risk of transmitting viral diseases such as human immunodeficiency virus (HIV) and hepatitis by blood transfusion had dropped dramatically in the last 25 years. This is the result of a multi-layered approach to safety. Today, 12 different tests are performed on each unit of blood donated for the following infectious diseases:
- HIV-1 and HIV-2
- Hepatitis B
- Hepatitis C
- Human T lymphocytotropic viruses (HTLV-1 and HTLV-2)
Sometimes additional testing is also done for diseases such as cytomegalovirus (CMV) and West Nile virus.
Complications of Blood Transfusions
Most patients who receive a transfusion don't suffer any adverse reactions. However, it's still possible for reactions to occur with any blood component. A reaction can occur at the time of the transfusion or not until weeks or months later.
Symptoms and side effects that may occur during or soon after transfusion include:
- Fever (called febrile reactions, these are the most common complications and usually aren't serious)
- A skin rash or hives (called urticaria, these are the second most common reaction)
- Pain at the transfusion site (arm vein)
- Back pain
- Shortness of breath
- A drop in blood pressure
- Dark or red urine
If you notice any of these changes during a transfusion, however slight, alert the nursing staff promptly. Serious complications can be prevented by recognizing a reaction early, stopping the transfusion and limiting the amount of blood given. Although rare, a hemolytic transfusion reaction can occur when transfused red cells are damaged or destroyed. This can result in a drop in blood pressure, bleeding or kidney damage that may be life-threatening.
Reactions that aren't immediate include:
- Alloimmunization. Alloimmunization occurs if you produce antibodies against certain antigens in transfused blood. While it doesn't necessarily cause immediate symptoms, blood centre staff needs to be aware of this reaction and take precautions if you undergo subsequent transfusions.
- Viral infection transmission. Since blood is a biological substance, it may never be entirely risk-free. But more sensitive tests have significantly reduced the chance of getting a viral disease over the last 20 years.
- Cytomegalovirus (CMV) transmission. CMV is a common virus, but in patients undergoing blood or marrow stem cell transplantation, it can cause serious problems, such as pneumonia.
- Bacterial infection transmission. A bacterial infection is extremely rare with red cell transfusions, occurring once in every million transfusions. Infection following platelet transfusions are more common than with red cell transfusions, but special precautions are taken at all U.S. blood centres to prevent this from happening.
- Graft versus host disease (GVHD). Although it's rare, donor white cells (lymphocytes) can attack the recipient's skin, liver, bowel and marrow after a blood transfusion. Fortunately, this severe complication is rare and almost never occurs after transfusion of irradiated blood.