More than 38,000 blood donations are needed every day, according to the American Red Cross. Many of these donations are given as blood transfusions to people with cancer who are undergoing chemotherapy or recovering from surgery. Blood transfusion is a procedure in which blood or a blood component is transferred from one individual (donor) to another (recipient). A person may choose to donate whole blood (the most common type of blood donation) or specific parts of the blood, such as red blood cells or platelets.

Why blood is needed

Blood carries oxygen and nutrients to every part of the body and takes away waste products. Blood cells are produced in the bone marrow, the spongy, inner mass of bone. Unlike some other products, blood cannot be artificially manufactured; it must come from a donor. The parts of the blood that are most commonly transfused are red blood cells, platelets, plasma, and cryoprecipitate.

Red blood cells contain hemoglobin, the protein that carries oxygen to the body. They are used to treat people who have anemia (a low number of red blood cells) from cancer and/or cancer treatment, or those who have lost blood through injury, surgery, or organ transplantation.

• Platelets are critical for clotting and helping to control bleeding. Platelet transfusions are given to people undergoing chemotherapy or bone marrow transplantation or to reduce the risk of bleeding.
  
  
• Plasma is the clear, straw-colored liquid portion of the blood that contains clotting properties that help control bleeding and antibodies that help fight infection. Plasma also helps maintain blood pressure and balances levels of sodium and potassium.
  
  
• Cryoprecipate is the part of the plasma that separates from the rest of the plasma when frozen and provides a higher concentration of clotting properties than regular plasma does.

Most donors give whole blood, which is then separated into the various components.

Who can donate

Donating blood is safe and simple. The American Red Cross requires donors to be healthy, weigh at least 110 lbs., and be age 17 or older. (Some states allow 16 year olds with the consent of a parent.) Healthy donors can donate blood every eight weeks. Before collection, all blood donors undergo a brief examination, which includes taking their temperature, pulse, and blood pressure, and testing their hemoglobin levels. In addition, donors must complete a confidential questionnaire to determine their eligibility to give blood.

Factors that may affect a donor’s eligibility include:

• Medications: Most do not pose a problem for potential blood donors. However, people taking certain medications must complete a waiting period after the last dose before they are eligible to donate blood. Talk with a nurse or doctor to find out if any of your medications fall into this category.
  
  
• A history of cancer: Most cancer survivors can donate blood if they have been cancer-free for 12 months. (People who have had a skin cancer removed do not need to wait 12 months.) People with a history of a blood cancer, such as leukemia or lymphoma, cannot donate blood.
  
  
• A history of other diseases or conditions, especially HIV/AIDS and hepatitis
  
  
• Recent travel to areas where malaria is common
  
  
• Pregnancy

The American Red Cross provides a complete list of eligibility criteria.

Donating blood

Before giving blood, donors should drink plenty of liquids, eat foods rich in iron (iron supplements are not necessary, except for strict vegans), and avoid fatty foods. Upon arrival at the donation center, donors should be prepared to provide identification and a short medical history, including current medications, and undergo a brief medical examination. All of the information a donor provides to the blood donation center is private and confidential.

It takes about 10 minutes to draw one pint of blood. The body will replace the plasma in a few hours and the cells within a few weeks. Immediately afterwards, donors receive a beverage and a snack to help restore fluids and nutrients to the body. For the rest of the day, donors are advised to drink more fluids and limit exercise.

After blood has been drawn, it is tested for ABO group (blood type, such as A, B, AB, or O) and Rh type (a type of protein on red blood cells; a person is either Rh-positive or Rh-negative), as well as for any unexpected red blood cell antibodies that may cause problems in a recipient. The blood is also screened for diseases, such as hepatitis and HIV, that can be spread to recipients.

Donating platelets

Platelet donation happens in a process called apheresis. This process is also used for donors who give other blood components, such as plasma or red blood cells. Apheresis takes up to two hours. During the donation, a machine draws blood from one arm through sterile tubing into a centrifuge, a machine that separates the cells. The centrifuge is programmed to separate platelets from the rest of the blood and return the remaining blood to the donor in a continuous process. This requires the donor to have two intravenous (IV) lines—one that draws the blood and another that returns it. The process is carefully monitored. Although apheresis is painless, some donors experience some mild side effects—such as tingling sensations, especially around the face and mouth, and feeling chilled—which the donation center staff can help manage.

For donors wishing to give platelets, recommendations include:

• Avoid aspirin in the 48 hours before a donation.
  
  
• Consume extra calcium and fluids before donating.
  
  
• Note that platelet donations may be given every three days but that most centers limit donations to 24 times per year.

More Information

Donating Umbilical Cord Blood

Donating Bone Marrow

Additional Resources

American Red Cross: Blood Facts

America’s Blood Centers: Blood Donation

Last Updated: May 24, 2010