Blood donation: What to expect

Blood donation helps save lives. Find out if you're eligible to donate blood and what to expect if you decide to donate.

Millions of people need blood transfusions each year. Some may need blood during surgery. Others depend on it after an accident or because they have a disease that requires blood components. Though the demand for blood is high and half of all Americans are eligible to donate, only about 5 percent of those eligible to give blood do so.

If you're in good health, you can probably donate. Find out about blood donation and what to expect if you decide to give.

Who can donate blood?

You can donate blood if you:

Are in good health
Are at least 17 years old (Some states allow teens to donate starting at 16. There's no upper age limit to donate blood.)
Weigh at least 110 pounds
Pass the physical and health history assessments

Blood donation centers carefully screen potential donors. The screening guidelines are necessary to ensure that blood donation is safe for you and that it's safe for the person who receives your blood.

During the screening process, you fill out a confidential medical history that includes direct questions about behaviors known to carry a higher risk of blood-borne infections — infections that are transmitted through the blood. These behaviors include prostitution, male homosexual activity and intravenous drug use. A trained staff member asks you about your health history and conducts a physical examination, which includes checking your blood pressure, pulse and temperature. Most common medical conditions, such as high blood pressure, and common medications, such as blood pressure pills, won't prevent you from becoming a blood donor. All of the information from this evaluation is kept strictly confidential.

Because of the threat of variant Creutzfeldt-Jakob disease (vCJD), also called mad cow disease, there are some guidelines potential blood donors should follow. VCJD is thought to be obtained by eating beef infected with mad cow disease. Those who should not donate blood include:

Anyone in the United States who has spent three months or more in the United Kingdom from 1980 through 1996
Anyone who has spent five years or more in Europe from 1980 to the present

During your blood donation procedure, a small sample of blood taken from a finger prick is used to check your hemoglobin level, the oxygen-carrying component of your blood. If your hemoglobin concentration is normal and you've met all the other screening requirements, you can donate blood.

What can you expect during the blood donation?

You lie or sit in a reclining chair with your arm extended on an armrest. A blood pressure cuff or tourniquet is placed around your upper arm to fill your veins with more blood. This makes the veins easier to see and easier to insert the needle into, and also helps fill the blood bag more quickly. Then the skin on the inside of your elbow is cleaned.

A new, sterile needle is inserted into a vein in your arm. This needle is attached to a thin, plastic tube and a blood bag. Once the needle is in place, you tighten your fist several times to help the blood flow from the vein into the bag. Blood initially is collected into tubes for testing. When these have been collected, blood is allowed to fill the bag, about one pint.

When complete, the needle is removed, a small bandage is placed on the needle site and a dressing is wrapped around your arm. The needle is in place about 10 to 20 minutes.

The collected unit of blood is processed into "components," which means the blood is separated into parts, such as:

Platelets. These cells help stop bleeding.
Red blood cells. These cells carry oxygen.
Plasma. This is the liquid part of your blood, which carries nutrients and helps stop bleeding.

Each of these can then be given to people who need different blood components. Your blood donation can help up to three people.

A type of blood donation that is becoming more common is known as apheresis. During this blood donation process, blood is removed from your body much like in other blood donation procedures but it is pumped into a machine. In the apheresis machine, the blood is separated into its parts and a specific component, such as platelets, is removed from the donated blood with the apheresis machine returning the other parts back into your body. Doing this allows more of that component to be collected, compared with a regular blood donation, and allows the blood collection center to take only what's needed. Apheresis takes longer than a standard blood donation procedure; typically about one to two hours.

What types of tests are done on the blood?

After donation, your blood is tested to determine your blood type — classified as A, B, AB and O — and your Rh factor. The Rh factor refers to the presence or absence of a specific antigen, a substance capable of stimulating an immune response, in the blood. So you're either Rh positive or Rh negative, meaning you carry the antigen or you don't. This information is important to know because your blood type and Rh factor must be compatible with the blood type and Rh factor of the person receiving your blood.

Breakdown of blood types in the United States
O positive	38 %
O negative	7 %
A positive	34 %
A negative	6 %
B positive	9 %
B negative	2 %
AB positive	3 %
AB negative	1 %

Source: American Red Cross, 2007

Certain infectious diseases can pass from the donor to the person receiving the blood. To prevent this, each unit of blood is tested for diseases such as West Nile virus, Chagas' disease, syphilis, hepatitis and human immunodeficiency virus (HIV), the virus that causes AIDS. If all tests are negative — showing no presence of these diseases — the blood is distributed for use in hospitals and clinics. If any test shows positive results, the blood bank notifies you, and your blood is discarded and not used.

What can you expect after blood donation?

After donating you sit in an observation area, where you rest and eat a light snack. After 15 minutes, you can leave. Wait at least four hours before removing the bandage from your arm.

For 24 hours after your blood donation:

Drink extra fluids
Avoid lifting with the arm used during your donation
Avoid strenuous exercise
Avoid taking aspirin or ibuprofen (Advil, Motrin, others)

You may experience an upset stomach or feel lightheaded or dizzy after donating blood. These symptoms usually go away after eating a meal and drinking fluids.

You might notice a bruise at the needle-stick site. You may also feel some pain, which usually lessens if you take an over-the-counter pain medication, such as acetaminophen. Contact the blood donor center or your doctor if you:

Continue to feel nauseated, lightheaded or dizzy after resting, eating and drinking.
Notice a raised bump, continued bleeding or pain at the needle-stick site when you remove the bandage.
Feel pain or tingling down your arm, into your fingers.
Become ill with signs and symptoms of a cold or flu, such as fever, headache or sore throat, within four days after your blood donation. Bacterial infections can be transmitted by your blood to a potential donor via transfusion, so it's important to let the blood donor center know if you become ill so that your blood won't be used.

What are the risks?

Blood donation is safe. New, sterile disposable equipment is used for each donor, so there's no risk of contracting a blood-borne infection by donating blood. Also, blood donor centers strictly enforce screening guidelines and eligibility requirements to make sure that donating will not harm the donor.

If you're a healthy adult, you can usually donate a pint of blood without it endangering your health. Within 24 hours of a blood donation, your body replaces the lost fluids. And after several weeks, your body replaces the lost red blood cells.