Blood Product Donation and Transfusion

What are transfusions?

To have a transfusion means to get blood or some part of it. The blood usually comes from another person, called a donor. Parts of the blood (blood products) are separated out so that a person getting the blood gets only the part they need. The rest of the blood products can then be given to others who need them. Blood and blood products are given (transfused) into a vein, through an intravenous (IV) line.

Blood transfusions save millions of lives in the United States every year. Recent estimates suggest that about half of Americans will need a blood transfusion at some point during their lives.

Transfusions of blood and blood products temporarily replace parts of the blood when a person has been bleeding, or when their bodies can't make enough blood. People sometimes need transfusions after injuries or surgery, or if they have cancer or certain other diseases.

Here, we will describe blood and its parts (also called components) and why they are important. We will also explain how blood is donated and transfused and how that relates to people with cancer. For more details on how this works in your community, please contact your local hospital or blood donation center.

Blood and its components

Blood is a vital mixture of cells and liquid pumped by the heart through the arteries and veins. It reaches all of the cells in the body, bringing them oxygen and nutrients and taking away carbon dioxide (CO₂) and other waste products. Blood is made up of many parts (components), such as red blood cells, white blood cells, platelets, plasma, clotting factors, and small proteins. Each of these components has a different job.

Whole blood

This is what people usually donate, and it contains all parts of the blood. Each donated unit is about a pint, which is around 475 milliliters. After it is taken, the whole blood is usually separated into several blood products, such as red blood cells, plasma, platelets, and/or cryoprecipitate. This allows doctors to give patients only what they need and also helps to get the most out of the donated blood supply. People rarely need whole blood transfusions.

Red blood cells (RBCs) give blood its color. Their job is to take oxygen through the bloodstream to every part of the body and bring carbon dioxide (CO₂) back to the lungs, where it is removed from the body when we exhale.

Red blood cells (and all other blood cells) are normally made in the bone marrow, the soft inner part of certain bones. The production of RBCs in the body is controlled by the kidneys. When the kidneys sense that there aren't enough RBCs in the blood, they release a hormone called erythropoietin that causes the bone marrow to make more.

When people need red blood cells, they get packed red blood cells (PRBCs). This blood component has much of the plasma and other cells removed from it.

Plasma, the clear pale-yellow liquid portion of blood, contains some clotting factors -- proteins that help make blood clot. This is important when the body is injured because clots are needed to help seal blood vessels and stop bleeding. Plasma also has other proteins, such as antibodies, which help fight infection. Once plasma is separated from the red blood cells, it can be frozen and kept for up to a year until it is needed. Once thawed, it is called fresh frozen plasma (FFP).

Plasma can be donated by itself in a process called apheresis, or sometimes called plasmapheresis. The donor is hooked up to a machine that removes blood, then separates the plasma and puts it into a special container. The machine then returns the red cells and other parts of the blood back to the donor's bloodstream.

Platelets are fragments of cells in blood that are another important part of the clotting process. They work with the clotting factors in plasma to help prevent unwanted bleeding. Platelets come from special cells called megakaryocytes. Like other early (immature) forms of blood cells, megakaryocytes are mainly found in the bone marrow.

Platelets are usually found in the plasma, but like red blood cells, they can be separated from it. A unit of whole blood contains only a small volume of platelets. It takes the platelets from several units of whole blood (from different donors) to help keep a person from bleeding. A unit of platelets is defined as the amount that can be separated from a unit of whole blood. Unlike red blood cells, platelets do not have a blood type (see the section, "Blood types"), so patients can usually get platelets from any qualified donor. For platelet transfusions, 6 to 10 units of these random donor platelets are usually combined and given to adult patients at one time (they are then called pooled platelets).

Platelets can also be collected by apheresis. This is sometimes called plateletpheresis. In this procedure, a donor is hooked up to a machine that removes the blood, and keeps just the platelets. Then the rest of the blood cells and plasma are returned to the donor. Apheresis can collect enough platelets so that they don't have to be combined with platelets from other donors. Platelets collected in this way are called single donor platelets. (More information about this is available in the section on blood donation below.)

Cryoprecipitate is the name given to the small fraction of plasma that separates out (precipitates) when plasma is frozen and then thawed in the refrigerator. It contains several clotting factors found in plasma, but they are now concentrated in a smaller amount of liquid. A unit of whole blood contains only a small amount of cryoprecipitate, so about 10 units of cryoprecipitate are usually pooled together for one transfusion.

Granulocytes are types of white blood cells (WBCs or leukocytes) that help the body fight infection. As with other types of blood cells, granulocytes are made in the bone marrow. When more of these WBCs are needed, the body normally makes substances called colony stimulating factors (CSFs), which cause the bone marrow to make more granulocytes.

Like platelets and plasma, granulocytes can be collected by apheresis, sometimes called leukopheresis. Granulocytes can also be separated out of a unit of whole blood from the plasma and RBCs into a product called buffy coat, which can then be transfused. Granulocytes are mainly used when people have very low white blood cell counts and have serious infections. Since man-made versions of colony stimulating factors are now available, along with better antibiotics, granulocyte transfusions have become rare.

Why cancer patients might need blood product transfusions

Blood product transfusions are used to replace important components of the blood when there are not enough in the body, either because they have been lost through bleeding or are not being made. There are many possible reasons people might need blood product transfusions, such as major bleeding (due to trauma or surgery) or diseases and treatments that slow production of blood cells.

People with cancer might need blood transfusions because of the cancer itself. For example:

• Some cancers (especially digestive system cancers) can cause internal bleeding, which can lead to anemia (too few red blood cells).
• Cancers that start in the bone marrow (such as leukemias) or cancers that spread there from other places may crowd out the normal blood-making cells, leading to low blood counts.
• People who have had cancer for some time may develop what is known as anemia of chronic disease. This anemia results from certain long-term medical conditions that affect the production and lifespan of red blood cells.
• Cancer can also lower blood counts in other ways by affecting organs such as the kidneys and spleen, which are involved in keeping enough cells in the blood.

Cancer treatments may also lead to the need for blood transfusions:

• Surgery to treat cancer is often a major operation, and blood loss may lead to a need for red blood cell or platelet transfusions.
• Most chemotherapy drugs affect cells in the bone marrow. This commonly leads to low levels of white blood cells and platelets, which can sometimes put a person at risk for life-threatening infections or bleeding.
• When radiation is used to treat a large area of the bones, it can affect the bone marrow and lead to low blood cell counts.
• Bone marrow transplant (BMT) or peripheral blood stem cell transplant (PBSCT) patients get large doses of chemotherapy and/or radiation therapy. This destroys the blood-making cells in the bone marrow. These patients often have very low blood cell counts after the procedure and may need transfusions.

Red blood cell transfusions

People who have low red blood cell (RBC) counts are said to have anemia or to be anemic. People who have anemia for any of the reasons above may need RBC transfusions because they don't have enough RBCs to carry oxygen to all of the cells in the body. Signs and symptoms of severe anemia can include paleness of the mouth, skin, and nail beds; dizziness; and shortness of breath.

Doctors check for and learn the severity of anemia by using blood tests to measure the following:

• Hemoglobin (Hb), which is the substance inside RBCs that carries oxygen. A normal hemoglobin count is about 14 to 18 grams per deciliter (g/dL) in men and about 12 to 16 g/dL in women. (Some labs may use slightly different values for normal.)
• Hematocrit (Hct), which is the percentage of blood made up of cells (as opposed to plasma). This is normally about 40% to 54% in men and about 37% to 47% in women. Again, this may vary slightly between labs.
• Other tests may look at the number, size, or shape of the RBCs; iron levels; or B₁₂ levels to give doctors a better idea as to the possible causes of anemia.

Not all patients with anemia need blood transfusions. Whether you may need a transfusion depends on many factors, such as how long it took for the anemia to develop and how well your body is able to cope with it. Anemia due to a sudden loss of blood will probably need to be corrected right away. Anemia that develops slowly is less likely to cause problems, as the body has time to adjust to it to some extent. If your hemoglobin level is lower than normal but you are not dizzy, pale, or short of breath, you may not need a transfusion.

Patients who have certain heart or lung diseases may need transfusions even if their hemoglobin level is not very low because they are more sensitive to the effects of anemia. Other conditions that increase the need for oxygen may also require transfusions.

Even when cancer patients need treatment for anemia, not all of them will need transfusions. Erythropoietin is the chemical normally made by the kidneys that causes the bone marrow to make its own red blood cells. Man-made versions of this chemical, such as epoetin (Procrit^®, Epogen^®) and darbepoetin (Aranesp^®) can be given as shots (injections). These medicines do not pose some of the risks of a transfusion (see below), but they do have their own risks. One of these drugs may be used instead of a red blood cell transfusion in patients whose chemotherapy is not expected to cure them. These drugs are expensive. And they don't work very quickly, so they can only be used if the need to raise the red blood cell levels is not urgent. It can take several weeks before these drugs increase the red blood count.

Low iron or B₁₂ levels are less common causes of anemia in cancer patients. These problems can also be corrected, but it can take many weeks for these drugs to restore red blood cell counts.

RBC transfusions before and during surgery: Transfusions may be given during or after surgery to make up for blood loss. In the past, doctors sometimes gave them before surgery because they knew some blood would be lost during the operation, and they felt that keeping the blood counts normal might help the healing process. Usually a transfusion was considered if a patient's hemoglobin level was below 10 g/dL.

But some studies have suggested patients with certain cancers, like colorectal, prostate, lung, and breast cancer, had a slightly higher risk of their cancer coming back if many transfusions were given before or during surgery. Transfused blood is thought to affect the immune system in ways that may cause problems later. The information can be hard to make sense of because many of the studies only looked at people who had and hadn't been transfused, so the groups may have started with major differences. For instance, patients who need transfusions are often sicker to start with, and they may be treated in different ways afterward. These studies need to be confirmed by careful research. There are other reasons to think twice about transfusions before surgery, such as the risks of transfusion reactions (described below). Keep in mind too, that while it may be possible to reduce the number of transfusions, totally avoiding them can cause serious risks or even death in some people.

Most doctors now feel that transfusions before surgery should not be given just because of low lab values. The decision to transfuse should be made in the context of other factors as well, such as the patient's symptoms and overall health.

Plasma transfusions

Plasma is commonly given to patients who are bleeding because their blood is not clotting the way it should. Cancer patients might also be given fresh frozen plasma (FFP) if they have a problem called disseminated intravascular coagulation (DIC). This is a rare condition where all of the clotting factors are used up or broken down in the body. Signs and symptoms (such as excessive bleeding and bruising) and lab tests (such as measuring fibrin breakdown products) help the doctor identify DIC.

Platelet transfusions

Cancer patients may need transfusions of platelets if their bone marrow is not making enough. This happens when platelet-producing bone marrow cells are damaged by chemotherapy or radiation therapy or when they are crowded out of the bone marrow by cancer cells.

A normal platelet count is about 150,000 to 400,000 platelets per cubic millimeter (mm³). When platelet counts drop below a certain level (often 20,000/mm³), a patient is at risk for dangerous bleeding. Doctors may think about giving a platelet transfusion when the platelet count drops to this level, or even at higher levels if a patient needs surgery and may be at risk of bleeding.

If there are no signs of bleeding, a platelet transfusion may not be needed even if the platelet count is low.

Currently there is one drug, known as interleukin-11 (oprelvekin or Neumega^®), that doctors can give to help raise platelet counts without transfusion. Like other medicines to help blood counts, it takes time for this drug to raise the platelet counts, anywhere from 10 to 21 days.

Cryoprecipitate transfusions

Cryoprecipitate may be given to replace several blood clotting factors such as:

• Factor VIII (missing in patients with hemophilia A)
• Von Willebrand factor (needed to help platelets work)
• Fibrinogen (the major part of a clot)

People with hemophilia are now more likely to get pure factor VIII or factor IX, which can be separated from the rest of the plasma. Unless they are bleeding, people with cancer rarely need cryoprecipitate.

Granulocyte transfusions

Chemotherapy can damage cells in the bone marrow, and patients getting chemo often have white blood cell (WBC) counts lower than the normal range of 4,000 per cubic millimeter (mm³) to 10,000/mm³.

Granulocytes, especially certain kinds of granulocytes known as neutrophils, are very important in fighting infections. When patients have low WBC counts, doctors carefully watch the number of neutrophils. The blood count that is watched is called the absolute neutrophil count, or ANC. People with neutropenia (an ANC below 1,000/mm³) are at risk for serious infections, even more so if the count stays down for longer than a week.

At one time, granulocyte transfusions were commonly given to cancer patients who could not make enough of these cells on their own or whose granulocytes had been destroyed by disease or medicines. But for many reasons, such transfusions are now rare. First, it is not clear how well the transfusions help in reducing the risk of serious infections. Granulocyte transfusions can also cause a fever known as a febrile transfusion reaction. And they can sometimes transmit infectious diseases, such as cytomegalovirus (CMV), which can be dangerous for people who have weak immune systems.

Instead of transfusing granulocytes, doctors now commonly use medicines called colony-stimulating factors or growth factors to help the body make its own neutrophils. There are 2 types of growth factors that help the body make neutrophils:

• Granulocyte colony-stimulating factor (G-CSF), such as
• Filgrastim (Neupogen^®)
• Pegfilgrastim (Neulasta^®)
• Granulocyte-macrophage colony-stimulating factor (GM-CSF), such as
• Sargramostim (Leukine^®)

Blood component transfusion -- what it involves

A transfusion is the infusion of a blood component through tubing connected to a needle or fine tube (catheter) that is put into a vein, usually in the arm. The amount and type of blood component transfused depends on what the patient needs.

A doctor may prescribe a transfusion for a cancer patient if he or she is having symptoms that may be related to low blood cell levels. First, lab tests such as a complete blood count (CBC) are done to find out if the patient's symptoms are likely to be helped by a transfusion. These tests measure the levels of components within the blood such as red blood cells, white blood cells, and platelets. Coagulation (clotting) tests may also be done if abnormal bleeding is involved.

Blood types

Not all blood is the same. People have different blood "types," which are based on substances called antigens on a person's blood cells. The 2 most important groups of antigens in blood typing are called ABO and Rh. Each person has 1 of 4 possible ABO types -- A, B, AB, or O -- which means antigen A, antigen B, both antigens, or neither antigen is found on their blood cells. Each person also has 1 of 2 possible Rh types -- you are Rh-positive or Rh-negative (you either have it or you don't). These 2 factors can be combined into 8 possible blood types.

Blood types are important when it comes to transfusions. If you get a transfusion that is not compatible with your blood type, your body's immune system could mount a defense against the donated blood. This can cause a serious or even life-threatening transfusion reaction (described below in the section, "Possible risks of blood product transfusion").

To be sure no mistakes are made, donated blood is carefully "typed" (tested to find out what type it is) both when it is taken from the donor and again once it is received by the hospital lab. The blood bag is labeled with the type of blood it contains. When a person needs a blood transfusion, a blood sample is drawn from him or her and tested the same way.

ABO blood types: Two antigens on blood cells (A and B) determine a person's ABO blood type (A, B, AB, or O). In the United States, the most common blood type is O (about 45% of the population), followed closely by type A.

If you have type O blood, you have neither A nor B antigens on your red blood cells, and your plasma has antibodies (immune system proteins) against both A and B antigens. You can only get type O red blood cell transfusions. But your red blood cells could be given to people with type A, B, AB, or O blood, which is why you are sometimes called a "universal donor." It is only in extreme emergencies that universal donor blood is used in this way. For example, if a person is bleeding severely and nearing death, there may no time for testing. In everyday practice, people in the US are always given the exact same type of red blood cells that they have.

If you have type A blood, you have the A antigen on your red blood cells. Since you do not have B antigen on your cells, your body makes antibodies against the B antigen. These antibodies are in your plasma and prevent you from getting either type B or AB red blood cells.

If you have a B blood type, you have the B antigen on your red blood cells and have antibodies against the A antigen in your plasma. You cannot be transfused with type A or AB red blood cells.

If you are an AB blood type, you have both the A and B antigens on your red blood cells and do not have antibodies against either of these antigens in your plasma. You can get transfusions of A, B, or AB red blood cells.

Rh factor: Blood is either Rh-positive or Rh-negative, depending on whether the red blood cells have Rh antigens on their surface. A person that has type A, Rh-positive blood is called "A positive," whereas a person with type A, Rh-negative blood would be "A negative."

If you have Rh-positive blood, you can get Rh-positive or Rh-negative red blood cell transfusions. But people with Rh-negative blood should only get Rh-negative red blood cells except in emergencies. Rh-positive blood can cause a person with Rh negative blood to make antibodies against the Rh factor. If an Rh-negative woman makes antibodies like this, it can cause harm to any Rh-positive babies she may have in the future. Her anti-Rh antibodies can attack Rh-positive blood cells in the fetus.

Other antigens: There are other antigens on red blood cells that can lead to transfusion reactions. These are rare because people do not make antibodies against them unless they have had a transfusion before. Still, these antigens may become a factor in finding matching blood for a person who has had many transfusions in this past, as is the case for some people with cancer.

Plasma, platelets, and blood type

Plasma transfusions follow a different set of rules than red blood cells and whole blood (based on the antibodies in the plasma):

• People with type O blood can get any type of plasma.
• People with type A blood can get A or AB plasma.
• People with type B blood can get B or AB plasma.
• People with type AB blood can get only AB plasma.

Rh type is usually not a factor in plasma transfusions.

For platelet and cryoprecipitate transfusions, matching the blood type of the donor to the recipient is usually not critical, but, if possible, labs usually do try to match them. This may become important in patients who have already had many transfusions or who have had transfusion reactions in the past.

Antibodies and cross-matching

After blood is typed, a test called an antibody screen is done to learn whether a patient's plasma contains other antibodies in addition to ABO and Rh. If there are extra antibodies, the cross-matching step (below) may take longer. This is because some units of donor blood may not fully match the recipient's, even though they have the same ABO and Rh types.

Before a person can get a transfusion of packed red blood cells, one more lab test called a cross-match must be done to make sure that the donor blood is compatible with the recipient's. A unit of the proper ABO and Rh type is selected, and a drop of donor blood is mixed with a drop of plasma from the patient. The mixture is watched to see if the patient's plasma causes the donor blood cells to clump. This may happen if the patient has extra antibodies to a protein in the donor unit. If there are no problems, a cross-match takes about 30 minutes.

A cross-match is usually not needed for a platelet or plasma transfusion unless the platelets look like they contain some red blood cells.

Getting a transfusion

Most blood transfusions are given in the hospital or in outpatient clinics. Acetaminophen (Tylenol^®) and diphenhydramine (Benadryl^®) are often given before a transfusion to help reduce the symptoms of some transfusion reactions. Blood or blood products are infused through a vein, usually in the arm. Red blood cell transfusions are usually started at a slow rate while the patient is watched closely for the signs and symptoms of a transfusion reaction. Vital signs (such as temperature, heart rate, and blood pressure) are checked often. Each unit of blood or blood product is usually transfused over a couple of hours. But smaller volumes of platelets take much less time. Always let your nurse know right away if you notice any symptoms such as itching, shivering, headache, chest or back pain, nausea, dizziness, trouble breathing, or other problems.

Getting blood transfusions at home: A visiting nurse can give blood transfusions in the home if precautions are taken to be sure the patient is kept safe. Patients who get home blood transfusions often have severe chronic illnesses, are not able to travel to a health care facility, and need frequent transfusions for a long time.

The same standards that apply to hospital transfusions must be followed in the home. A doctor must be sure that a patient's heart and lung function are stable before they can be transfused at home. Emergency medical care must be available close by if needed. Also, care must be taken to make sure the blood is kept at the proper temperature while being taken to the home.

Possible risks of blood product transfusions

Although blood transfusions can be life-saving, they are not without risks. Infections were once the main risk, but have become extremely rare with careful testing and donor screening. Transfusion reactions and other non-infectious problems are now more common.

Transfusion reactions

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 get it. After that, both a nurse and blood bank lab technician look 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 like diphenhydramine (Benadryl). In rare cases these reactions can be more serious.

Febrile reaction: Febrile 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 other 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.)

Infections

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 quickly. This can affect about 1 in every 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 units that are found to be affected. These tests are still being refined, but today 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. A 2009 study on hepatitis B in donated blood suggests that the risk is about 1 in every 350,000 units or less. About 1 blood transfusion in about 2 million may transmit hepatitis C. Work continues to be done 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 1 in 2,000,000 or less. 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.

Alternatives to blood transfusion

Because blood transfusions carry risks and because the blood supply is limited, doctors try not to transfuse if they can avoid it. In some cases, options other than blood product transfusions may be available.

Volume expanders: When a patient has lost a lot of body fluids but does not need red blood cells or other blood cells, shock may be treated or prevented by giving solutions to keep the circulation going. The most common solutions are normal saline (sterile water with a precise amount of salt) and lactated Ringer's solution (saline plus other chemicals). Other such solutions (called volume expanders) include albumin, hydroxyethyl starch (HES), dextrans, and purified protein fractions. All of these increase volume, but do not change the number of blood cells.

Growth factors: As described in the section "Why cancer patients might need blood product transfusions," the body naturally makes hormone-like substances called hematopoietic growth factors that cause the bone marrow to make more blood cells. Scientists have learned how to make some of these growth factors in the lab to help people with low blood cell counts. Growth factors can be used to boost red blood cell, white blood cell, or platelet counts.

Growth factors may help patients who would otherwise need transfusions. But they have some drawbacks that may limit their use in some cases:

• Unlike transfusions, growth factors often take many days or even weeks to raise blood counts, so they may not be useful in people who need blood cell levels raised quickly, such as those with active bleeding.
• People who have severe bone marrow disease may not respond to the growth factors because they do not have enough blood-producing cells in their bone marrow.
• Some growth factors might cause certain types of cancer cells (such as lymphocytic leukemia, multiple myeloma, head and neck cancer, breast cancer, cervical cancer, and some kinds of lung cancer cells) to grow more quickly.
• Growth factors generally cost a lot more than transfusions.

Because of these drawbacks, certain growth factors are not used in people whose treatment is expected to cure their cancer. And when they are used, they are given for as short a time as possible.

Intra-operative or post-operative blood salvage: Patients getting surgery sometimes need transfusions to replace the blood lost during or after the operation. In some cases this lost blood can be "salvaged" or saved by collecting it with a special machine and giving it back into the patient. Giving a person back his or her own (autologous) blood cuts down on the need for transfusions from other donors. But some studies have found tumor cells in blood salvaged during cancer operations, so this is not something that can be done for all patients. (Another type of autologous transfusion is described in the "Blood donation" section below.)

Blood substitutes: So far, there is no real substitute for human blood. But researchers are working to develop a liquid that can carry oxygen and replace blood, at least for a short time, in certain situations. Products that are being tested include hemoglobin-based oxygen carriers and perfluorochemical compounds. They can do some of the work of red blood cells, such as carrying oxygen to tissues, but cannot replace the many functions that human blood does. Of the oxygen-carrying compounds that are being tested in US clinical trials, none has been approved by the FDA as of 2010.

Most blood substitutes are experimental and are rarely used. They may be used as a short-term measure in patients whose religious beliefs do not allow them to have blood product transfusions. They may also help patients with rare blood types and those whose immune systems would destroy donated blood. The substitutes may be used until matching donated blood can be found, which in some cases might take several days.

Blood donation

Despite all our medical advances, there is still no good man-made substitute for human blood, which is why blood donations are so important. People donate blood for different reasons -- some do it for friends, family members, or even themselves. Others volunteer so that they can help people they don't even know.

Blood is usually donated at special collection centers. Some centers use vans (often called bloodmobiles) that travel to different areas to collect blood donations. Some larger hospitals have their own centers to collect and process donated blood. After blood is tested for safety and processed into components, it is sent to blood banks, where it is stored until needed.

Keeping the blood supply safe

In the United States, all blood centers follow careful procedures to keep the blood supply safe. Everyone who comes in to donate is asked many questions and has a chance to say whether their blood may be unsafe for any reason. Also, previous donation records and lists of ineligible donors are checked. Lab tests are done to look for blood that might transmit diseases (described in "Possible risks of blood product transfusions," above). People are not allowed to donate blood if their lab tests or questionnaires show that they may be at high risk for certain diseases.

In response to learning that TRALI is linked to certain donor antibodies, blood banks are now screening donors to avoid transfusing plasma from people who are likely to have these antibodies. Other parts of the blood are used as usual, but the donors' plasma is not given to patients -- it may be used to make medicines.

The US Food and Drug Administration (FDA) considers blood a "biologic" (much like a drug) and closely regulates it to ensure the safety of the blood supply. The American Association of Blood Banks also publishes guidelines for safe transfusions, which its members must follow.

Donating blood is safe

Rules on who can donate help protect the donor as well as the recipient.

Aside from protecting those who receive donated blood, rules are also in place to protect people who want to donate. Although guidelines can vary slightly by state and facility, for the most part donors must:

• Be healthy
• Be at least 17 years old
• Weigh at least 110 pounds
• Not have donated blood within the past 8 weeks (this can be shorter for most apheresis donations)
• Not be taking antibiotics

People who are taking "blood thinners" or certain drugs that are used to treat acne, baldness, or an enlarged prostate may not be able to donate unless they've stopped the drug for a few days or weeks. People who have taken certain drugs for psoriasis or taken products made from human plasma or tissues may be kept from donating blood even longer. There are other health and travel questions that are reviewed with each donor in detail. (See "The donation process" below.)

Other safety details

Only sterile equipment is used to collect blood. The needle used to draw blood from your vein has never been used before, and it is thrown away right after it is used. Donors cannot get hepatitis, HIV, or other infections or diseases from giving blood. Reactions from donating are rare and are almost always minor when they do happen. If you are healthy, you can donate a unit (about a pint) of blood without harm because one unit is a small part of your total blood volume. Your body will replace the lost fluid within a day, and your bone marrow will replace all of the blood cells, usually within a couple of weeks.

If you are interested in donating blood, contact the American Association of Blood Banks (AABB) for a list of member institutions, or visit their online blood bank locator. Or you can contact America's Blood Centers or the American Red Cross for donation centers near you. (See the "Additional resources" section for contact info.)

The donation process

Before giving blood, get a good night's sleep, eat a well-balanced meal, and drink extra fluids that are caffeine-free. Some donor centers ask that you bring in a list of all the medicines you are taking.

FDA guidelines require that before giving blood, you must register, have your vital signs checked, answer health questions, and get a blood test (usually by sticking the finger for a few drops of blood). The center will have you fill out a questionnaire, asking about certain behaviors or travel that might put you at increased risk for certain diseases. You must also be informed about donation before you decide to donate and actually give the blood.

You will be asked to sit in a reclining chair or lie on a table. An area on your arm will be cleaned, and a sterile needle put into a vein (usually where your elbow bends). Removing a unit of whole blood usually takes only about 10 to 15 minutes. Apheresis donation (described below in the section, "Types of donation") may take 2 hours or longer.

Once your blood is taken, you will be asked to stay for a short time to make sure you are feeling well. During this time you are encouraged to drink fluids (such as fruit juice) and eat a light snack before leaving. The whole process, from registration to snack, takes about an hour. Although you can take part in normal activities soon after giving blood, some centers recommend that you have someone else drive home after you donate. You may feel tired, but this will usually only last a few hours.

Types of donations

There are several types of blood product donations.

Volunteer whole blood donation: Most blood donations come as units of whole blood from volunteers who have no connection to the person who will receive it. Once donated, the units are usually separated into component parts.

Apheresis donation: Apheresis allows volunteers to donate just one blood component. Blood is drawn out through a vein in the arm, and a machine separates out the needed component (usually platelets, although red blood cells, white blood cells, and plasma can also be collected this way). The rest of the blood is then returned to the donor, usually through a vein in the other arm. This procedure usually takes 2 or more hours.

The advantage of this type of donation is that, since most of the blood is returned, a large amount of a needed component can be collected. Patients who need many platelet transfusions, such as some cancer patients, are exposed to fewer donors in this way than they would be from pooled platelets coming from many donors. This cuts down on the risk of both transfusion reactions and infections.

As with whole blood donation, apheresis donors should:

• Get a good night's sleep.
• Eat a well-balanced meal.

Drink extra caffeine-free fluids before donating.

Since aspirin makes platelets less useful to a transfusion recipient, donors are usually asked not take aspirin within 36 hours before donation. The same FDA guidelines as those for whole blood donation must be followed. Unlike whole blood donors, those who give platelets or plasma via apheresis usually can give again in a couple of weeks. Different blood centers may have different rules about this.

During the apheresis procedure, donors may feel cold, or they may feel a slight tingling sensation around the lips and nose, but this goes away once the procedure is completed. (It is caused by the drug that is used to keep the blood from clotting in the machine.) Other side effects, such as feeling tired, are much like those from whole blood donation.

Autologous blood donation: Donating your own blood for later use is called autologous (meaning "from the self") donation. Autologous donation is most often done in the weeks before you have a scheduled surgery that will likely require blood transfusion. The blood can then be used during or after the operation to replace any blood you may have lost. This is generally thought to be the safest form of blood transfusion because you're getting your own blood back. But it is not totally without risk. There is always the very small chance that bacterial contamination or clerical errors can happen. People who aren't able to donate blood for others may still be able to donate blood for themselves.

There is a processing fee for collecting, testing, storing, and delivering each unit of autologous blood. Be aware that your health insurance may not fully reimburse you for this cost. There is also a need to plan ahead so that you have enough time before surgery to have your blood cell counts go back to normal levels after blood has been collected.

Directed donation: Donating blood for a family member, friend, or other specified patient is called directed donation. This can be done at any blood donation center. The donor must meet the same requirements as for regular blood donation, and the donor's blood must be compatible with (match the blood type of) the recipient.

Blood from directed donors is not usually any safer than blood from other volunteer donors and in some cases may actually be more likely to cause problems. (See "Graft-versus-host disease" under "Transfusion reactions.") The same types of testing are still done on blood from directed donors. As with autologous donation, there is a processing fee for collecting, testing, and delivering each unit of directed donor blood. This fee may not be fully reimbursed by health insurance.

Paid donation: Blood from paid donors cannot be used in the United States for transfusion purposes. Plasma is the only component for which donors are sometimes paid, and it is taken by the apheresis method. Plasma can be treated for safety in ways that blood cells cannot. Plasma taken from paid donors is generally treated and processed by pharmaceutical companies into drugs. It cannot be transfused in the form of cryoprecipitate or fresh frozen plasma.

Donation by cancer survivors

Many cancer survivors are keenly aware of the value of good health and want to help others by donating their blood or body organs. But for the safety of blood or organ recipients, centers may restrict donations from people diagnosed or with a history of certain cancers.

Blood donation

Some people who have had cancer are not allowed to donate blood for a certain length of time after treatment. This is done partly to protect the donor, but it may also add an extra margin of safety for the person who receives the blood. If you aren't sure if you are well enough to give blood, talk with your doctor before you try to donate.

While cancer has very rarely been transmitted through transplants of solid organs such as kidneys, cancer transmission by blood transfusion has not been reported in the medical literature. To check this, a group of researchers looked at back in time at people who had received blood from donors who had developed cancer within 5 years of giving the blood. They found no increased cancer risk in those who got blood from those who were found to have cancer soon after donating. This would suggest that the chance of getting cancer from a blood donor with cancer is extremely small, if it exists at all. Even if cancer cells were present in donated blood, the immune system of the person getting the blood would destroy the cells. A possible exception might be in transfusion recipients with weakened immune systems, who might not be able to fend off the cancer cells. Because of this slight possibility, people whose cancer is thought to be growing or spreading are not allowed to donate blood for other people.

Different blood collection centers may have slightly different standards for allowing cancer survivors to donate. For example, the American Red Cross allows most people who have had cancer to donate if the cancer was treated at least 1 to 5 years ago and the cancer has not come back. (The time can vary at different blood centers.) Potential donors whose cancers had not spread and required no further treatment besides surgery to remove the cancer have little chance of cancer cells getting into the bloodstream. These low-risk donors may need to wait only until they've healed from their surgery and feel well again to donate blood.

You cannot donate blood if:

• You are being treated for cancer
• Your cancer is spreading or has come back
• You have had leukemia or lymphoma as an adult
• You have ever had Kaposi's sarcoma

People who had leukemia or lymphoma as children are often allowed to donate after 10 years of being cancer-free.

Different blood donation centers may have different requirements. The final decision about whether a person is allowed to donate is up to the doctor in charge of the donor center. If you have questions about whether you can donate, please contact the blood collecting center in your community.

Some cancer survivors may find these precautions frustrating. They may be eager to donate blood to help others with cancer, just as they were helped by transfusions during their treatment. Everyone should remember, though, that the most important goal in blood banking is to ensure the safety of the blood supply and to protect those who get the transfusions.

Organ donation

Many cancer survivors also wish to help people by becoming organ donors. There is always a pressing need for organ donation. According to the United Network for Organ Sharing (UNOS), the organization that facilitates every organ transplant in the United States, more than 100,000 people are waiting for organs. Some organ donations, such as kidney donation, may be done when a person is still living. Others are possible only if a person wishing to donate passes away under certain circumstances.

The risk of passing on cancer to the person who gets an organ is very small, but there have been some rare reports in the medical literature of this happening. The risk is higher for organ transplants than blood transfusions, in part because organ recipients are given drugs to suppress their immune systems to help prevent rejection of the transplant.

According to a study by UNOS, under certain circumstances there may be an acceptable risk in using organs from donors who have had certain types of cancer. This is particularly true if there is a long cancer-free interval before the organ donation. At present, UNOS does not recommend accepting organs from people with "actively spreading cancer (except for primary brain tumors that have not spread beyond the brain stem)." Acceptance of organs for donation is up to each organ procurement agency and the recipient. If you have questions about whether you may be able to donate your organs, please contact UNOS (see the "Additional resources" section below) or the organ procurement center in your community.

For many people, donating the corneas from their eyes is another way to offer help to others after they pass away. Almost all people with cancer (except those with certain blood or eye cancers) can donate their corneas. Corneal donation does not delay the funeral and the body is not disfigured.

Additional resources

National organizations and Web sites*

AABB (American Association of Blood Banks)
Telephone: 301-215-6526)
Web site: www.aabb.org

America's Blood Centers
Toll-free number: 1-888-US-BLOOD (1-888-872-5663)
Web site: www.americasblood.org

American Red Cross
Toll-free number: 1-800-733-2767
Web site: www.redcross.org

United Network for Organ Sharing (UNOS)
Toll-free number: 1-888-TXINFO1 (1-888-894-6361)
Web site: www.unos.org

No matter who you are, we can help. Contact us anytime, day or night, for information and support. Call us at 1-800-227-2345 or visit www.cancer.org.

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