Blood Transfusions

Dr. Oller talks about Blood Transfusions.

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 maximize safety of blood donation for the donor and the recipient.

For people who are considering donating blood, a local blood center can describe the criteria for being a blood donor. The websites at the end of this topic also include information about eligibility criteria, which may vary slightly between different blood centers. People who have a pre-existing medical condition may wish to consult their own health care provider.


— Several 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 whether they can safely donate blood without experiencing any negative health effects [1].

Heart, lung, and blood disease – Potential donors are asked if they have ever had heart, lung, or blood diseases. People with heart disease, heart valve conditions, irregular heartbeat, disease of the blood vessels in the brain, heart failure, and certain lung conditions may be excluded from blood donation, or they may be allowed to donate blood provided this has been cleared with their health care provider and they have had no major symptoms in the prior six months. Certain blood diseases such as iron deficiency anemia or chronic leukemia may also lead to exclusion.

Other medical conditions – Potential donors are asked if they feel healthy and well on the day of donation. A prospective donor should mention other serious medical conditions to the donor health historian who will then evaluate eligibility to donate.

Seizures – People with a history of seizures can donate blood, provided they have had no seizures within a certain period of time (usually one to six months).

Recent surgery – People who have undergone recent surgery are permitted to donate blood when healing is complete and they have resumed full activity. However, 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 the pregnancy ends.

Age requirement – The minimum age for blood donation is 16 or 17 years, depending upon the state. When allowed, 16-year-olds must bring a signed permission form from a parent. In most cases, there is no upper age limit for donation, although approval from the donor’s physician is required in some cases.

Weight requirement – Individuals weighing less than 50 kg (110 pounds) are not permitted to donate blood. The less a donor weighs, the greater the likelihood of having a reaction such as dizziness and fainting following 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. Most blood centers perform an additional evaluation of donors aged 16 to 18 who are just over the weight limit, which takes into account the donor’s estimated blood volume, calculated from the donor’s height and weight. There is no upper weight limit for donating blood, although some centers have an upper weight limit based on the size/weight limit of the donor phlebotomy chair.

Questions are also asked that address the safety of the transfusion for the person receiving the blood, such as the possibility of getting an infection from the transfusion.

Medical evaluation — In addition to a medical history, donors undergo a brief physical examination 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 (generally higher than 180/100), very high or very low heart rate (with the exception of highly conditioned athletes and those on beta blocker medication), or an irregular heartbeat are temporarily not permitted to donate blood.

Blood test – A small blood sample is taken from a fingerstick and 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 after they donate. Individuals with hemoglobin levels that are too low are temporarily not permitted to donate blood. During the donation, the donor is seated comfortably in a chair, and a needle is put in the arm to remove the blood. This is done slowly enough so that possible symptoms such as lightheadedness are minimized. One unit of blood is removed (approximately 500 mL or about a pint). The person is monitored during the donation and given some juice or other liquids or snacks afterwards.

Time interval until next donation — According to US Food and Drug Administration (FDA) regulations, donors are eligible to donate no sooner than 56 days (eight weeks) after their previous donation. However, not all donors will be able to qualify at this minimum interval, as it depends upon how rapidly the person’s body is able to replenish its red blood cells. For example, women who have heavy 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.

Donating blood removes iron from the body, and this can result in temporary iron deficiency if the lost iron is not replaced before the next donation. The risk of iron deficiency is highest in teenage donors, premenopausal women, and individuals who donate frequently (such as men of any age and women over 50 who donate three or more times per year, or women under age 50 who donate two or more times per year). Because the strategy of eating iron-rich foods is not sufficient to replenish lost iron, many blood organizations recommend that people at increased risk for iron deficiency take a multivitamin with iron or an iron-only supplement for approximately 60 days to replace the iron lost through each blood donation.

APHERESIS DONATION — A technology called apheresis has made it possible to collect specific components of blood. Apheresis is used to selectively collect red blood cells, platelets (blood components that play an important role in clotting), plasma, and granulocytes (a type of infection-fighting white blood cell). The procedure is done in the blood center or at a blood drive and involves inserting a needle in a vein in each arm. Blood is withdrawn through one needle, passed through an apparatus that separates plasma from specific types of blood cells (platelets or red blood cells) and retains the desired component, and then the remainder of the blood is returned to the donor through the other needle. It takes from one to two hours.

Red blood cells – Donors can give red blood cells by apheresis once every 16 weeks. This is less frequent than whole blood donation because a greater number of red blood cells are collected during the apheresis procedure.

Platelets – Donors can give platelets up to 24 times per year. Approximately 1 percent of people have a mild reaction to one of the substances (citrate) that is 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 glucocorticoid medication called dexamethasone on the day before donation to increase the number of granulocytes in their blood. Glucocorticoids are usually not given to individuals who have diabetes, gastrointestinal ulcers, or glaucoma. 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.

Screening questionnaire and laboratory testing for possible infections – A variety of different measures, including self-reporting of infectious exposures and other infectious disease risk factors are used for this screening. A sample of the blood is tested in the laboratory for a variety of infections.

Elimination of payment for donation – Since the late 1970s, volunteer donors have been the source of all whole blood and blood components in the United States. Donors are sometimes paid for donating plasma that is used to manufacture other blood products. However, to protect the recipient, these products undergo additional treatment to kill any infectious agents that might be in the product.

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 HIV infection or risk factors for HIV, including questions about any signs or symptoms of HIV and behaviors that increase the risk of HIV. Such behaviors include using non-prescription intravenous (IV) drugs, having sex with a prostitute or in exchange for money or drugs, and for men, having sex with another man. Depending on your answers to these questions, you may not be allowed to donate blood, or you may need to wait for a period of time before you are eligible. In December 2015, the guidelines for men who have sex with men were changed; rather than being ineligible to donate blood indefinitely, the wait period is now at least one year from the last sexual contact with another man.

People who want to be tested for HIV or other sexually transmitted infections should not donate blood for this purpose. Even though donated blood is tested for HIV, the tests are not perfect and there is a small possibility that a person who might have been exposed to HIV could transmit the virus to a recipient if they donate blood. Free and anonymous HIV testing is available elsewhere (see

Hepatitis — Hepatitis is a viral infection that causes inflammation of the liver. Blood donors are routinely screened to determine whether they have been exposed to (or infected with) hepatitis B or C viruses.

People who have had sexual contact or have lived in the same dwelling (eg, house, dormitory) with someone who has hepatitis B or hepatitis C are disqualified for 12 months after their last exposure to that person, depending upon the particulars of the exposure. A similar deferral is applied in the case of exposure to people with viral hepatitis of unknown origin.

People who have ever had a confirmed positive test for hepatitis B surface antigen (a marker for hepatitis B virus infection) are permanently disqualified from donating blood. Hepatitis B vaccination may temporarily cause this test to become positive [2]. In order to avoid being disqualified as a blood donor, a person who has recently received the hepatitis B vaccine should wait 21 days before donating blood. At that time, this test should be negative. Donors with false positive or vaccine-induced positive hepatitis B surface antigen results can be requalified to donate if the blood center follows a stringent protocol and a sufficient amount of time has elapsed.

Donors are not asked if they have ever had viral hepatitis. However, if a person volunteers the information that they previously had hepatitis B or C, most blood centers will defer such donors, since a positive laboratory test would require the donated blood to be destroyed.

In the event that a community is experiencing an ongoing outbreak of hepatitis A, temporary deferral procedures for exposure to this agent could be put in place.

People who have received a blood transfusion are not permitted to donate blood for 12 months after the date of transfusion.

In some states, people who have received a tattoo are not permitted to donate blood for 12 months. In many other states, where the tattooing industry is carefully regulated by state law to ensure that the procedures are sterile, donation may be permitted without the need for any waiting period. With regard to ear or body piercing, donation is allowed if the procedure was performed with sterile or single-use equipment.

Zika virus — Zika virus causes a mild infection in most people, but if a pregnant woman is infected, the virus can cause miscarriage or serious brain abnormalities in the baby. Testing of blood for Zika virus has been done in the United States since the summer of 2017.

Parasitic diseases — Blood donors are routinely asked questions about possible exposure to several diseases caused by parasites that can be transmitted by blood transfusion.

Malaria – Transfusion-transmitted malaria is common in some parts of the world but is 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 occurs are not permitted to donate blood for one year after they leave the area, 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) by transfusion is rare in the United States. Blood donors are asked if they have ever had Chagas disease, and most donated blood is tested for Chagas disease.

Transmission of babesiosis (a malaria-like illness spread by ticks) by transfusion is uncommon. Blood donors are asked if they have ever had this disease. In areas where babesiosis is more common, blood may be tested for it.

Prion diseases — Creutzfeldt-Jakob disease (CJD) is a rare but fatal neurologic disease. Variant Creutzfeldt-Jakob disease (vCJD) is a related but pathophysiologically distinct disease that first appeared in the United Kingdom (UK) in 1996. Affected individuals may have no symptoms of CJD or vCJD for many years. The infectious agent of both these diseases is an abnormally folded protein called a prion.

To date, there have been no reported cases of transfusion-related transmission of CJD and only four reports of probable transmission of vCJD in the UK. Despite this 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 to 1996, or

Have spent ≥5 cumulative years in Europe from 1980 to 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 to 1990 or elsewhere in Europe from 1980 to 1996, or

Received a blood transfusion in the UK or France between 1980 to present, or

Injected bovine (from cows) insulin from the UK or other countries with a history of mad cow disease (bovine spongiform encephalopathy)

In December 2017, the US Food and Drug Administration (FDA) published a new draft guidance document, which, if implemented, would modify the second item above to: “Have spent ≥5 cumulative years in France or Ireland from 1980 to 2001.” This time- and country-limited criterion would be less restrictive than the deferral for travel to Europe.

Bacterial infection — Certain bacteria normally live on the skin and in the digestive tract. Bacteria can get into donated blood if a donor has a bacterial infection, if bacteria on the skin gets into the blood from the needle stick, or if there is a 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.

Other infections — Donated blood cannot be tested for every possible infection, and new types of infections are frequently emerging around the world. The pre-donation educational material given to donors, as well as the questionnaire, includes several general questions that are designed to identify individuals who either have infection symptoms or who have travelled to locations where these infections are more common. In addition, the blood center also informs donors that they should call the blood center if specific medical symptoms develop in the two weeks following donation; this is so the donated unit can be removed from the blood supply. However, questions in the pre-donation questionnaire are directed at general signs of infection, and individuals who might be at risk of transmitting an infection due to travel or behaviors are asked to “self-defer,” which means to avoid donating blood. The decision to self-defer can be made at the time of donation or after the donation has been completed (in which case the center will not use or distribute the donated blood).

Other medical conditions — In order to protect the recipient against non-infectious complications, the donor is evaluated for 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 or tissue (such as the lung, liver, breast) are permitted to donate if they have been symptom- and cancer-free for a period of time off of treatment as defined by the blood collection facility. This time period varies but is at least one year.

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 without any waiting period.

Hemochromatosis – Individuals with hereditary hemochromatosis (a condition in which frequent removal of blood is the standard treatment) can donate their blood for transfusion if they meet other criteria for being a donor and if the blood bank has met certain regulations from the FDA. The acceptance of blood donations from these individuals has not been uniformly implemented, perhaps due to the costs of meeting regulations and removing financial incentives to blood donation. The FDA maintains a list of collection centers that accept these donations [3].

There is no risk of transmitting hemochromatosis to the recipient.

Recent vaccinations — There are strict standards for when you can donate blood after you have received a vaccination. When you go to donate blood, you will be asked if you have had any recent vaccinations. If you have, you might have to postpone your blood donation.

For some live or attenuated (weakened) viral or bacterial vaccines (measles, mumps, oral polio, oral typhoid, yellow fever), you have to wait at least two weeks before donating your blood. For rubella or varicella zoster vaccines, you have to wait four weeks.

Medications — Most medications taken by donors do not pose a risk to recipients. However, a number of drugs are known to cause birth defects and are considered during donor screening:

Etretinate (brand name: Tegison), used for psoriasis

Acitretin (brand name: Soriatane), also used for psoriasis

Isotretinoin (brand names: Absorbica, Amnesteem, Claravis, Myorisan, Zenatane; formerly known as Accutane in the United States), used for acne

Finasteride (brand names: Propecia, Proscar), used for benign prostatic hypertrophy or hair loss

Dutasteride (brand name: Avodart), usually given for prostatic enlargement

Vismodegib (brand name: Erivedge), used for basal cell skin cancer

Donors who have taken isotretinoin and finasteride are asked to wait one month after the last dose before donating blood; donors who have taken dutasteride are asked to wait six months; donors who have taken vismodegib are asked to wait two years; and donors who have taken acitretin are asked to wait three years. Individuals who have taken etretinate are permanently disqualified from donating blood. People who took aspirin or aspirin-containing medications within the previous 48 hours are allowed to donate whole blood but are not allowed to donate platelets by apheresis. People who took anti-platelet drugs (eg, clopidogrel [sample brand name: Plavix] or ticagrelor [sample brand name: Brilinta]) must wait a variable period ranging from 2 to 14 days to donate platelets by apheresis. People who took anti-clotting medications (also called “blood thinners”) are generally not allowed to donate blood for a minimum of two or seven days (depending on the specific medication) after the last dose. Anti-clotting medicines include warfarin (sample brand name: Coumadin), dabigatran (brand name: Pradaxa), rivaroxaban (brand name: Xarelto), apixaban (brand name: Eliquis), edoxaban (brand names: Savaysa, Lixiana), and heparin (given by injection; sample brand name: Lovenox).

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), West Nile virus, Zika virus, syphilis, and Chagas disease.

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 or HIV infection. Theoretically, it is possible that an individual with one of these diseases could have a positive test result 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 and after donation. The reason for the deferral is not usually available to staff at the collection facility.

Telephone callbacks — After donating blood, donors are given a phone number so that they 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 to two weeks after donating (such as symptoms of upper respiratory tract infection, gastrointestinal illness, or infection with a virus transmitted by mosquitos). Such reports will be evaluated, and the unit of blood may be 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. The likelihood of getting one of these infections from a blood transfusion is lower than the likelihood of dying in a car crash or of being killed by a firearm. Recent estimates suggest the following risks of developing certain infections after receiving a unit of blood:

1 in 200,000 to 1 in 360,000 for hepatitis B

1 in 1 million to 1 in 2 million for hepatitis C

1 in 1.5 million to 1 in 2 million for human immunodeficiency virus (HIV)

1 in 2 million for human T-lymphotropic virus (HTLV)

OTHER RISKS FROM A TRANSFUSION — In addition to the risk of infection from transfusion, other risks include the following:

Shortness of breath due to immune/inflammatory reactions, known as transfusion-associated acute lung injury (TRALI)

Shortness of breath due to the large volume of fluid, known as transfusion associated circulatory overload (TACO)

Allergic reactions to proteins and/or cells in the transfusion

Immune attack of the recipient by the transfused cells, also called transfusion-associated graft-versus-host disease (ta-GVHD)

Blood incompatibility, leading to destruction of the transfused cells by the recipient’s immune system

Fever due to fever-causing hormones (cytokines) in the transfusion, also called febrile nonhemolytic transfusion reaction (FNHTR)

These risks occur infrequently and are well known to clinicians; measures are taken routinely in order to minimize them further.

AUTOLOGOUS BLOOD DONATION — Autologous blood donation is when a donor donates blood for her or himself several days to six weeks ahead of a scheduled surgery, when blood might be needed. Autologous blood donation reduces the risk of most, but not all, infectious complications of blood transfusion.

POTENTIAL COMPLICATIONS OF BLOOD DONATION — Most people who donate blood do not have any complications that require medical care. The most common complications include bruising or soreness at the needle site and fatigue.

A small percentage (2 to 5 percent) of people feel faint and/or pass out before, during, or after donating blood. This is more common the first time a person donates and in people who are younger. Drinking a 16-ounce (473 mL) bottle of water before donating may reduce this risk.
Dr. Carlo Oller Board Certified Emergency Physician Please visit my website, make sure you subscribe, comment, and share! That is the best way to show your support.

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