INTRODUCTION — Blood is essential for transporting oxygen, nutrients, and other substances to tissues throughout the body. Donated blood can be lifesaving for individuals who have lost blood because of accidents or surgery, as well as for people who have become severely anemic or have dangerously low platelet counts because of certain medical conditions and/or treatments.
Screening measures help to ensure that blood donation is safe for the donor and that transfusion is safe for the recipient. These measures are very effective, and complications of blood donation and transfusion are rare.
For people who are considering donating blood, a local blood bank can describe the criteria for being a blood donor. The web sites at the end of this topic also include information about eligibility criteria (see "Where to get more information" below). People who have a preexisting medical condition may wish to consult their own healthcare provider.
SCREENING MEASURES TO PROTECT THE DONOR — Several screening measures are used to ensure that blood donation is safe for the donor and is unlikely to have any negative health effects.
Medical history interview — All blood donors are asked questions about their medical history to help determine if they can safely donate blood without experiencing any negative health effects
. During the donation, one unit of blood (approximately 450 mL or 15 fluid ounces) is removed.
- Heart and lung disease — Potential donors are asked if they have ever had heart, lung, or blood diseases. In general, people with heart disease, heart valve conditions, irregular heartbeat, disease of the blood vessels in the brain, congestive heart failure, and certain lung conditions are not allowed to donate blood.
- Other medical conditions - Potential donors are asked if they feel healthy and well on the day of donation. If the donor provides information about medical conditions when answering this question, their eligibility to donate will be evaluated by the blood collection staff.
- Seizures — People with a history of seizures can donate blood provided they have had no seizures within the past 12 months, with or without medications.
- Recent surgery — People who have undergone recent surgery are not permitted to donate blood until healing is complete and they have resumed full activity. If a transfusion was given at the time of surgery, donation is not allowed for one year.
- Pregnancy — Women who are pregnant are not permitted to donate blood during pregnancy and for six weeks after delivery.
- Age requirement — The minimum age for blood donation is 16 or 17 years, depending upon the state. Donors who are 16 years of age need written consent from a parent or guardian. In most cases, there is no upper age limit for donation.
- Weight requirement — Individuals weighing less than 50 kg (110 pounds) are usually not permitted to donate blood. The less a donor weighs, the greater the likelihood of a reaction to blood donation. Although reactions to blood donation are rare, individuals weighing between 50 and 54 kg (110 and 119 pounds) are most likely to experience reactions such as dizziness and fainting following donation.
Medical evaluation — Donors undergo brief medical testing before donation to check for any obvious signs of illness or conditions that would disqualify them from blood donation.
- Vital signs — The pulse, blood pressure, and temperature of a donor are checked before donation. Individuals with a fever, high blood pressure, very high or very low pulse rate (with the exception of highly conditioned athletes), or an irregular heart beat are not permitted to donate blood.
- Blood test — A small blood sample, usually taken from a fingerstick, is tested to check for the number of red cells or the amount of hemoglobin in the blood. This is done to ensure that the donor is not anemic or likely to become anemic or iron deficient after they donate. Individuals with hemoglobin levels that are too low are temporarily not permitted to donate blood.
Time interval until next donation — Donors are eligible to donate another unit of blood 56 days after their previous donation (five times per year). However, the frequency of donation depends upon how rapidly each individual's body replenishes the donated blood and blood components. Some donors, especially women who have menstrual periods, will not be able to donate every 56 days because their iron stores are not sufficient to replenish the lost red blood cells.
APHERESIS DONATION — A technology called apheresis has made it possible to collect specific components of blood during the donation procedure. Apheresis is used to selectively collect red blood cells, platelets (blood components that play an important role in clotting), and granulocytes (a type of infection-fighting white blood cell).
- Red blood cells — Donors can give red blood cells by apheresis once every 16 weeks. This is less frequently than whole blood donation because a greater amount of red blood cells are collected during the apheresis procedure.
- Platelets — Donors can give platelets up to 24 times per year. About 1 percent of people have a reaction to citrate, one of the substances mixed with the blood during platelet donation; the reaction can include feelings of numbness and tingling, muscle cramping, and nausea. The reaction can be treated or prevented by taking a calcium supplement before or during the donation.
- Granulocytes — Donors of granulocytes may be given granulocyte colony stimulating factor (G-CSF) and/or a steroid called dexamethasone on the day before donation to increase the number of granulocytes in their blood. Steroids are usually not given to individuals who have high blood pressure, diabetes, gastrointestinal ulcers, glaucoma, tuberculosis, or fungal infections. The side effects of G-CSF and dexamethasone may include headache, joint pain, fatigue, insomnia, allergic reactions, and fever.
SCREENING MEASURES TO PROTECT THE RECIPIENT — Screening of blood donors helps to ensure that the donated blood is safe for transfusion into a recipient. A variety of different measures are used for this screening.
- Careful selection of donation sites — Organizations that collect blood choose donation sites carefully. Blood is not collected in areas and facilities where infectious diseases are known to be more common.
- Elimination of payment for donation — Most organizations have stopped paying donors for their blood. Since the late 1970s, volunteer donors have been the source of almost all whole blood and blood components (red blood cells, platelets, fresh frozen plasma, and cryoprecipitate) collected and transfused in the United States. Donors are sometimes paid for other blood products (albumin, immunoglobulins, and factors VIII and IX). However, these products undergo additional testing to protect the recipient.
Screening for infections
Human immunodeficiency virus (HIV) — The human immunodeficiency virus (HIV) is the virus that causes AIDS. A variety of measures are used to screen donors for potential or actual HIV infection:
Donors are told about the risk factors for HIV and the potential for transmitting HIV through donated blood. Donors are also told that early in HIV infection, an individual may be infected and capable of transmitting HIV despite a negative HIV test. Donors are also given information about obtaining HIV testing at another location.
Donors are told that all donated units of blood are tested for the presence of HIV and that if the results are positive, the donor will be notified, and his/her name will be placed in a donor deferral registry (a list of individuals who are not permitted to donate blood).
Donors are told not to donate if they have symptoms of HIV infection or AIDS. These symptoms include persistent fever, night sweats, unexplained weight loss, persistent cough or shortness of breath, persistent diarrhea, swollen lymph nodes for more than one month, whitish lesions in the mouth, or bluish-purple spots on the skin or in the mouth. (See "Patient information: Symptoms of HIV infection").
Donors are also asked questions about behaviors that are known to increase the risk for HIV infection.
Finally, donors must sign an informed consent form stating that they understand that they should not donate blood if they are at risk for HIV infection.
Donors will be permanently disqualified from donating if they answer "yes" to any of the following questions:
- Have you ever had clinical or laboratory evidence of AIDS or HIV infection?
- For men: have you had sex with another man, even once, since 1977?
- Have you ever injected intravenous drugs?
- Have you engaged in sex in exchange for money or drugs since 1977?
- Have you ever received clotting factor concentrates for hemophilia or other clotting disorders?
Donors are also asked questions about their behaviors during the previous 12 months. Donors answering "yes" to any part of the following question will be temporarily disqualified from donating blood. This disqualification is removed 12 months after the last potential exposure:
Have you had sex in the past 12 months with:
- A person who has HIV infection or AIDS?
- A person that exchanged money for sex?
- A person who currently or previously used intravenous drugs?
- For women: a man who has sex with another man?
- A person receiving clotting factor concentrates?
Donors will also be asked the following questions pertaining to the past 12 months:
- Have you had syphilis or gonorrhea?
- Have you received a blood transfusion?
- Have you had an accidental needle stick injury or a blood splash to mucous membranes (tissues lining the eyes, nose, or mouth) or broken skin?
Donors will be asked if they have spent at least 72 hours in a prison in the past 12 months. Individuals answering "yes" may not be permitted to donate blood for at least 12 months from the last day of imprisonment.
Donors will also be asked if they were born in Cameroon or the surrounding West African countries, if they have received a blood transfusion or medical treatment in these countries, and if they have had sexual contact with anyone who was born in or lived in these countries since 1977.
Hepatitis — Hepatitis is an infection that causes inflammation of the liver. Blood donors are routinely screened to determine if they have or have been exposed to hepatitis.
- People who have had hepatitis (A, B, or C) after age 10 are permanently disqualified from donating blood.
- People who have ever had a positive test for hepatitis B surface antigen (a marker for hepatitis B) are permanently disqualified from donating blood.
- People who have had sexual contact or have lived in the same dwelling (eg, house, dormitory) with someone who has hepatitis (A, B, or C) are disqualified for 12 months after their last exposure to that person.
- People who have received a blood transfusion are not permitted to donate blood for 12 months after the date of transfusion.
- In most states, people who have received a tattoo or a body piercing are not permitted to donate blood for 12 months. In some states, where these industries are carefully regulated by state law to ensure that the procedures are sterile, earlier donation may be permitted.
West Nile virus infection — Initial blood donor screening for the presence of non-specific complaints (eg, fever) may help to identify donors at risk of transmitting West Nile Virus (WNV) infection. However, because most WNV-infected donors do not have symptoms, blood banks in the United States perform laboratory testing for WNV as part of their routine screening procedure. (See "Patient information: West Nile virus infection").
Parasitic diseases — Blood donors are routinely asked questions about possible exposure to several parasitic diseases that can be transmitted by blood transfusion.
- Malaria — Transfusion transmitted malaria is common in some parts of the world but extremely rare in the United States.Donors who have had malaria are not permitted to donate for three years after they become free of symptoms. Travelers to regions where malaria is common are not permitted to donate blood for one year after their return to the United States, provided they have not had symptoms of malaria. Immigrants from or residents of countries where malaria is common are not permitted to donate for three years after their departure from that country. (Residency is usually defined as living in the country for at least five years.)
- Chagas' disease and babesiosis — Transmission of Chagas' disease (American trypanosomiasis) and babesiosis (a malaria-like illness spread by ticks) by transfusion is rare. Blood donors are simply asked if they have ever had either of these diseases.
- Creutzfeldt-Jakob disease (CJD) and variant CJD — Creutzfeldt-Jakob disease (CJD) is a rare but fatal neurologic disease. Variant Creutzfeldt-Jakob disease (vCJD) is a somewhat similar disease that first appeared in the United Kingdom (UK) in 1996. Affected individuals may have no symptoms of CJD or vCJD for many years.
To date, there have been no reported cases of transfusion-related transmission of CJD and only three reports of probable transmission of vCJD in the UK. Despite this theoretical (CJD) or extremely small (vCJD) risk, donors who meet one or more of the following criteria are not allowed to donate:
- Have spent ≥3 cumulative months in the UK from 1980-1996, or
- Have spent ≥5 cumulative years in Europe from 1980-present, or
- As current or former US military personnel, civilian military employees and their dependents, have lived for ≥6 months at US military bases in Northern Europe from 1980-1990 or elsewhere in Europe from 1980-1996, or
- Received a blood transfusion in the UK between 1980-present, or
- Injected bovine (from cows) insulin sourced from the UK or other countries with a history of mad cow disease (bovine spongiform encephalopathy)
Bacterial infection — Bacteria can get into donated blood if a donor has a bacterial infection, if bacteria on the skin gets into the blood, or if there is an skin infection near the location where the blood is drawn. To reduce the likelihood of bacterial contamination of blood, the skin around the site is carefully examined and cleaned before the needle is inserted.
Donors who have a fever, who do not feel well, or who are taking oral antibiotics (except for acne) are not permitted to donate blood. These restrictions also apply to individuals who are banking blood for their own use (autologous transfusion).
Other medical conditions — In order to protect the recipient against non-infectious complications, the donor is evaluated for the presence of certain medical conditions before blood donation.
- Cancer — There have been no reported cases of the transmission of cancer by blood transfusion. However, because such transmission is theoretically possible, donors are screened for a history of cancer.
Donors who have had cancer of a solid organ (such as the lung or liver) are permitted to donate only if they have been symptom-free and cancer-free for a prolonged period of time, usually five years.
Donors who have had blood cancers (such as leukemia or lymphoma) are permanently disqualified from donating.
Donors who have had a superficial cancer that has been completely removed by surgery (such as basal cell cancer of the skin or early cervical cancer) can donate blood.
- Hemochromatosis — Individuals with hereditary hemochromatosis, a condition in which frequent donation of blood is the standard treatment, can donate this blood if they meet other criteria for being a donor and if the blood bank has met certain regulations from the Food and Drug Administration (FDA). There is no risk of transmitting this condition to the recipient.
Medications — Most medications taken by donors do not pose a risk to recipients. However, five drugs are known to cause birth defects and are considered during donor screening:
- Etretinate (Tegison®), used for severe psoriasis
Acitretin (Soriatane®), also used for severe psoriasis
Isotretinoin (Accutane®), used for severe acne
Finasteride (Propecia®, Proscar®) used for benign prostatic hypertrophy and hair loss.
Dutasteride (Avodart®) usually given for prostatic enlargement
Donors who have taken isotretinoin and finasteride are asked to wait one month after last taking the drug before donating blood, donors who have taken dutasteride are asked to wait six months, and donors who have taken acitretin are asked to wait three years after last taking the drug. Individuals who have taken etretinate are permanently disqualified from donating blood.
Laboratory testing of donated blood — After a unit of blood has been donated, the blood is tested in a laboratory for infectious diseases that can be transmitted by blood transfusion. These include tests for HIV, hepatitis B, hepatitis C, human T-lymphotropic virus (HTLV), and West Nile virus. In addition, when platelets are collected by apheresis or made from a unit of whole blood, most blood banks test the platelets for the presence of bacteria.
Confidential unit exclusion (CUE) — The confidential unit exclusion (CUE) process allows someone who has donated blood to confidentially indicate that his or her blood should not be given to others. This process protects individuals who feel pressured to donate at the workplace or during community blood drives. Donors are asked to make this indication after the interview, but before donation, usually by placing computerized bar code stickers on donation forms. This procedure is used by some, but not all, US blood banks.
Registry of deferred donors — A registry of deferred donors contains names of individuals who have been disqualified from blood donation in the past. Some donors in the registry have infectious diseases such as hepatitis B and HIV infection; individuals with these diseases may have positive test results at one time but negative test results at a later time. Other donors in the registry have provided information in the past that disqualified them from blood donation. A donor's name is usually checked against this registry before or after donation.
Telephone callbacks — After donating blood, donors can call the donation center to report any factors that may affect the use of their blood or to report symptoms of infections in the first days after donating (such as symptoms of upper respiratory tract infection or gastrointestinal illness). Such reports will be evaluated and the unit of blood given by the donor may be removed from inventory and destroyed.
RISK OF INFECTION FROM A TRANSFUSION — Safety measures, such as improved screening tests, have dramatically reduced the risk of acquiring a viral infection from a blood transfusion. Recent estimates suggest the following risks of developing certain infections after receiving a unit of blood:
- One in 250,000 for hepatitis B
- One in 1.9 million for hepatitis C
- One in 2.1 million for human immunodeficiency virus (HIV)
- One in 2 million for human T-cell lymphoma/leukemia virus (HTLV)
AUTOLOGOUS BLOOD DONATION — Autologous blood donation is when a person donates blood several days to six weeks ahead of a surgery, when blood might be needed. Autologous blood donation reduces the risk of most but not all infectious complications of blood transfusion.
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.uptodate.com/patients). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
Some of the most pertinent include:
Professional Level Information:
Laboratory testing of donated blood
Procedures used for blood donor screening: Protection of potential blood donors and recipients
Blood donor medical history
Controversial areas in preoperative autologous blood donation
Directed (designated) blood donation programs
Preoperative autologous blood donation
Indications for red cell transfusion in the adult
Massive blood transfusion
Transfusion of plasma components
Use of red blood cells for transfusion
General principles of home blood transfusion
Immunologic blood transfusion reactions
Intraoperative and postoperative blood salvage
Leukoreduction to prevent complications of blood transfusion
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable.
- National Library of Medicine
- National Heart, Lung, and Blood Institute
- American Association of Blood Banks