Blood safety


Overview: Blood safety refers to the procedures used to collect and store human blood products for the purpose of injecting them into another human being for medical reasons.

In vertebrates, blood is made of cells (erythrocytes and leukocytes) suspended in a fluid called plasma. Plasma is composed of 90% water and contains minerals, hormones, glucose, proteins, carbon dioxide, platelets, and blood cells.

Erythrocytes, also known as red blood cells or RBCs, are the largest and most prevalent blood cells. Hemoglobin, an iron-containing protein, gives RBCs their red color and helps transport oxygen throughout the body.

Leukocytes, called white blood cells or WBCs, are part of the body's immune system and help fight against infections. Leukocytosis, an indicator of disease, is a state in which there is an increase of leukocytes in the blood, usually signifying the presence of an infection.

There are two different groups of leukocytes: granulocytes and agranulocytes. Granulocytes have granules in their cells. There are three types of granulocytes: neutrophils, basophils, and eosinophils. Agranulocytes include monocytes, macrophages (monocytes found in the body's tissues), and lymphocytes. Some granules contain heparin, chondroitin sulfate or histamines, while others contain proteins and enzymes, which are toxic to bacteria and parasites. All leukocytes have a specific role in protecting the body.

Dendritic cells, similar to macrophages, activate T-lymphocytes and are important in cellular immunity.

During a blood transfusion, blood products are transferred from one person to another. The first successful human blood transfusion was performed in 1818 by Dr. James Blundell, a British obstetrician. Dr. Blundell was seeking a solution to the fatal hemorrhaging that frequently occurred in women after childbirth. For his first attempt at transfusion, the obstetrician removed four ounces of blood from the husband of one of his patients and injected the blood into his own wife.

Blood types: Blood is categorized as type A, type B, type AB, or type O, depending on the inherited antigens found on the surface of the red blood cells. O is the most common blood type. The Rh (Rhesus) factor is an inherited characteristic of blood; it refers to a type of protein that is either found on the surface of red blood cells (i.e., the Rh factor is "positive") or not found (i.e., "negative"). The Rh factor is expressed as either negative or positive in conjunction with a person's blood type.

Agglutination: Agglutination, or blood clumping, occurs when different blood types are mixed together. Agglutination-related reactions may range from a slight fever and mild breathing difficulties to more severe effects, such as high fevers, back pain, blood in the urine, and kidney failure. Agglutination is not the same process as clotting: When blood clots, it accumulates in a mass in order to plug tears or holes in damaged blood vessels.

Laboratory technicians test blood for agglutination during cross-matching. This procedure helps to determine if a quantity of blood is suitable for a particular recipient.

Other reactions: If a blood transfusion recipient is given an incompatible type of blood, a severe, sometimes-fatal reaction (called an acute hemolytic reaction) may occur.

A simple allergic reaction, with itching and rash, occurs in about 1 out of 333 blood transfusion recipients. A more severe reaction is also possible, resulting in fever, chills, low back pain, low blood pressure, shock, and kidney failure. Fatal severe reactions occur in about 1 out of 250,000 transfusion recipients, while nonfatal severe reactions occur in 1 out of every 6,000 transfusions.

Storing blood: In the early 1900s, researchers discovered that blood could be kept for several days if it was treated with anticoagulants (substances that prevent blood from clotting) and then refrigerated. With this discovery, blood banks became possible. The first blood bank was created in 1937 at Cook County Hospital in Chicago; the term "blood bank" was coined at that time by Dr. Bernard Fantus.

In the 1930s and 1940s, researchers conducted laboratory studies to learn more about the composition and preservation of blood and blood products. During this time frame, it was discovered that blood cells could be separated from plasma. Dr. Charles Drew helped create new techniques to produce large-scale quantities of plasma.

Contamination is less likely when blood components are stored separately; as a result, these components could now be kept for longer periods of time. This separation and subsequent refrigeration of blood products allows blood to be stored for 35 days without deterioration.

In 1950, Carl Walter and W.P. Murphy, Jr. introduced the use of plastic bags for blood collection, replacing fragile glass collection bottles. Durable plastic bags made it easier to develop a system of collection and preparation of multiple blood products from a single unit of whole blood.

When one "unit" (equal to a pint, or about two cups) of whole blood is taken from a blood donor, the red cells, plasma, and platelets are separated into different containers and stored according to a recipient's (or recipients') specific needs. Temperature plays an important role in blood product storage: Plasma must be frozen as soon as possible, at - -25 degrees Celsius or colder or colder, while red cells should be refrigerated between 2 and 6 degrees Celsius. Ca Platelets are kept in continuous shaking platforms at room temperature, between 20 and 24 degrees Celsius.


General: Each year Americans donate about 12 million units of blood, which are then processed into 20 million units of blood products (such as plasma, immune globulin and albumin). About 3.6 million Americans per year receive blood transfusions.

Donor requirements: In the United States, eligible blood donors must be at least 17 years old, weigh at least 110 pounds, and be in generally good health. In order to screen out unsuitable candidates, potential donors are asked several questions about their drug use and sexual habits.

Sometimes a person may be temporarily unable to donate blood: possible reasons include pregnancy; recent travel to countries that have a high incidence of specific contagious diseases; low levels of iron in the blood (iron levels fluctuate daily); recent immunizations; particular health conditions; and the taking of certain medications. In the United States, a person may donate blood every 56 days.

Regulating blood products: The U.S. Food and Drug Administration's (FDA) Center for Biologics Evaluation and Research (CBER) regulates and aims to increase the nation's blood supply. The World Health Organization (WHO) coordinates blood transfusion safety issues through six international offices and a network of volunteers.

The U.S. President's Emergency Plan for AIDS Relief (PEPFAR), a program begun by President George Bush, coordinates the activities of seven U.S. government departments in assisting developing nations to reduce the threat of transfusion-transmitted infections. In 2008, PEPFAR provided about $92.4 million for medical transmission prevention activities in 14 countries. For example, PEPFAR has funded antiretrovirals (medications that combat retroviruses like HIV) for people who could otherwise not afford to take them. This funding has included direct support for 5,287 blood-safety programs, as well as support for blood safety training or retraining for 9,838 people.

The World Health Organization (WHO) supports an increase in safeguards for blood donors, the use of blood banking, the detection of unsuitable blood donors, and efforts to screen blood donations for HIV. Despite the provision of trained personnel, sterile supplies, and testing materials, however, it was estimated that one-quarter of the 2.3 million units of blood donated in sub-Saharan Africa in 1995 was positive for HIV.

Transfusion transmitted infections: Strict safety precautions are taken to prevent transfusion-transmitted infections (TTIs), such as the human immune deficiency virus (HIV), hepatitis B and C viruses, cytomegalovirus, malaria, syphilis, human T-lymphotropic virus, and the West Nile virus.

The FDA has developed a rigorous screening program for potential blood donors, identifying high-risk behaviors that may indicate the potential for infection. The FDA estimates that direct questioning before blood donation eliminates about 90% of unsuitable donors. Donors may be asked about their sexual activities (specifically unprotected sexual activity between males, with prostitutes, or with drug users), and the donors' drug use (specifically, the sharing of needles for intravenous drug use).

Since March 1985, all blood products have been tested for antibodies to HIV-1 (the most common type of HIV). Since June 1992, all blood products have also been tested for antibodies to HIV-2 (a less common type of HIV that is predominantly found in Africa). In 1996, the FDA recommended that all donated whole blood or its components (red blood cells, plasma, and platelets) be screened for the HIV virus itself. The virus may be detected about one week before the actual detection of antibodies.

All blood products that test positive for HIV or HIV antibodies are safely discarded. Currently, the risk of contracting HIV after a blood transfusion in the United States is extremely low. According to the World Health Organization (WHO), the U.S. blood supply is among the safest in the world. Nearly all of the HIV infections that were acquired through blood transfusions occurred prior to 1985, before donated blood was tested for the virus.

In 1995, the risk of acquiring HIV-1 infection through a blood transfusion was estimated to be between 1 in 450,000-660,000 units of blood. By 2003, this estimated risk decreased to between 1 in 1.4-1.8 million units of blood. According to the National Heart, Lung and Blood Institute, only about 1 in 2 million donations possibly carries HIV and transmits the virus to a blood recipient. Blood donations that test positive for HIV antibodies are discarded.

The risk of having a donation that carries hepatitis B is about 1 in 205,000. The risk for hepatitis C is 1 in 2 million.

Variant Creutzfeldt-Jakob disease (vCJD) is the human version of Mad Cow Disease, a rare, yet fatal brain disorder. The possibility of getting vCJD from a blood transfusion is very low. People who may have been exposed to vCJD cannot be blood donors.


According to the World Health Organization (WHO), countries with higher per capita incomes generally have high blood donation rates, more available blood, more voluntary donors, and more efficient blood collection systems.

People who live in developing countries, especially sub-Saharan Africa, are more likely than industrialized nations like the United States to receive blood that is contaminated with infectious diseases, such as HIV, hepatitis, malaria and syphilis. Developing countries often have a higher incidence of infectious diseases, inadequate screening for antibodies (in some countries), and a higher risk of HIV contamination in blood supplies despite antibody screening.

Some countries are unable to test blood because they cannot afford the necessary reagents and test kits. In sub-Saharan Africa, about 22% of countries report that they do not have an adequate system to store blood. These countries have neither the necessary storage facilities nor a consistent supply of electricity to refrigerate blood and blood products; refrigeration is necessary to prevent the growth of bacteria in blood products. In addition, about 51% of countries in sub-Saharan Africa report that they have experienced interruptions in shipments of blood products. This problem is especially common in areas that are faced with political instability and armed conflict. In general, poor countries lack funding to employ and train healthcare workers to safely handle blood and blood products.

Many countries are dependent on emergency blood donations from paid donors or family members. In 2008, the WHO reported that 92% of blood donations in developed countries were from voluntary unpaid donors compared to77% in developing countries. A few developing countries have made substantial efforts to encourage voluntary blood donations. However, some reviews suggest that blood collected from paid donors or family members may have higher risks of containing blood-borne pathogens. Also, in areas that have high HIV prevalence rates, it may be difficult to identify low-risk volunteer blood donors.

Five different hepatitis viruses have been identified worldwide: Hepatitis types A, B, and C are common in the United States, while hepatitis types D and E are more common in other parts of the world. Hepatitis types A and E are spread through fecal matter from an infected person. Hepatitis types B, C and D are transmitted through infected blood, semen, or other body fluids. Hepatitis D is relatively common in the Middle East, in sub-Saharan Africa, in the Mediterranean countries, and in the northern countries of South-America. Hepatitis E is more prevalent in Southeast Asia, Africa, India, and Central America and is spread through fecal-contaminated water and food.

The American Red Cross estimates that 1 in 205,000 blood transfusions transmits hepatitis B to recipients, and 1 in 2 million transfusions transmits hepatitis C to blood recipients. Potential blood donors are asked questions regarding their sexual history and drug use, during a screening procedure that is designed to reduce the collection of contaminated blood. In addition to hepatitis, donated blood in the U.S. is also tested for syphilis, West Nile virus, and the viruses that cause T-cell leukemia and lymphoma. Other diseases, such as malaria and Chagas disease, may still be transmitted by blood transfusion; however, these diseases are rarely found in the U.S. blood supply due to the donation screening process.


Regulating blood products: The U.S. Food and Drug Administration's (FDA) Center for Biologics Evaluation and Research (CBER) regulates and aims to increase the nation's blood supply.

The World Health Organization (WHO) coordinates blood transfusion safety issues through six international offices and a network of volunteers. The WHO supports efforts to screen blood donations for HIV, to detect unsuitable donors, to increase safeguards for blood donors, and to establish blood banks. Despite efforts to provide trained personnel and sterile supplies and testing materials, in 1995 it was estimated that one-quarter of the 2.3 million units of blood donated in sub-Saharan Africa was positive for HIV.

Women and children (worldwide): In developing countries, women of childbearing age and children who are 1-3 years old require the most blood transfusions. Women usually require transfusion as a result of pregnancy-related complications, while children may need transfusions as a result of malnutrition, malaria, and/or severe anemia. According to the World Health Organization (WHO), more than half a million women worldwide die each year from complications related to pregnancy and childbirth. Most of these deaths occur in developing countries.

Children who have severe anemia as a result of malaria receive almost 70% of all blood transfusions in Africa. In the southern African region, up to 20% of maternal deaths and 15% of child deaths are due to severe malaria-related anemia. More than 536,000 women die each year during pregnancy or childbirth, with 99% of these deaths occurring in developing countries. Hemorrhage leading to blood loss is the main cause of maternal deaths worldwide, accounting for up to 44% of maternal deaths in some areas of sub-Saharan Africa.

HIV and other transfusion-transmitted infections: The most common infections that may be transmitted through blood transfusions are HIV-1, HIV-2, human T-lymphotropic virus (HTLV-1 and HTLV-2), hepatitis C virus, hepatitis B virus, West Nile virus (all donated blood in the U.S. is screened for this virus), treponema pallidum (the bacterium that causes syphilis), malaria, Chagas disease (rare outside of South America), variant Creutzfeldt-Jakob Disease or "Mad Cow Disease," and cytomegalovirus (CMV, which is a major problem for newborns and for patients with compromised immune systems).

The risk of contracting HIV after a blood transfusion in the United States is extremely low. According to the WHO, the U.S. blood supply is among the safest in the world. Nearly all of the HIV infections that were acquired through blood transfusions occurred prior to 1985, before donated blood was tested for the virus.

In countries with a high incidence of HIV among blood donors, the risk of transmitting the disease is especially elevated. However, several studies suggest that blood transfusions are not the major cause of HIV transmission in most countries. Instead, unprotected sexual contact and shared needles for illicit drug injections are the main causes of HIV transmission.

Of the 193 WHO Member States, only 43% test donors' blood for HIV, hepatitis C, and hepatitis B viruses. Researchers estimate that transfusion-transmitted HIV infection accounts for 80,000-160,000 infections annually, contributing 2-4% of all cases of HIV transmission. In 2000, the WHO estimated that 25% of the blood transfused in Africa was not tested for HIV. Consequently, about 5-10% of HIV infections in Africa in 2000 were transmitted by blood transfusions.

Blood donation safety: Apheresis is the process by which blood components are separated at the time of donation, with one or more components (most often red blood cells) being reinjected into the donor. Sodium citrate is used as an anticoagulant, or blood thinner, during this process. Although uncommon, a donor may have a reaction to sodium citrate. Most often, though, sodium citrate binds to calcium in the blood, causing hypocalcemia (low blood calcium levels). Symptoms of hypocalcemia include a tingling sensation on the lips, in addition to heart rhythm irregularities. Sometimes a donor is given a calcium-rich food or drink during the donation process so that reactions will not occur.

Blood transfusion safety: According to the WHO Blood Transfusion Safety team, there are seven important points for all WHO Member States to integrate into their national blood safety policies and procedures: establishment of a nationwide coordinated blood transfusion service; collection of blood from well-screened volunteer donors; rigorous testing of all donated blood; production of blood components with appropriate storage; appropriate clinical use; safe transfusion; and the development of a comprehensive quality assurance program that monitors the entire process.


General: In developed countries, blood transfusions are most commonly used to treat traumatic injuries and to support invasive medical procedures and surgeries, such as open-heart surgery and organ transplants. In developing nations it is used more often in pregnancy-related complications and to treat severe childhood anemia.

Ethical and health issues surrounding blood transfusions may eventually require the regulation of procedures such as xenotransplantation, which is the interspecies exchange of tissue, organs or fluids. Each day in the United States, 10 people die waiting for life-saving organ transplants.

Education and research: The American Association of Blood Banks is an international organization that provides up-to-date information about transfusion and cellular therapies and technologies. The organization's membership includes physicians, nurses, scientists, blood bank administrators, blood donor recruiters, medical technologists, and public relations practitioners. The U.S. Food and Drug Administration (FDA) maintains the Center for Biologics Evaluation and Research, whose mission it is to regulate the use of biologics for human use.

International blood donation: The WHO supports efforts to screen blood donations for HIV; it also supports the detection of unsuitable blood donors, an increase in safeguards for blood donors, and the establishment of blood banks. Despite efforts to provide trained personnel and sterile supplies and testing materials, in 1995 it was estimated that one-quarter of the 2.3 million units of blood donated in sub-Saharan Africa was positive for HIV. While there is still a deficit in supplies and educated personnel needed for efficient blood donation and blood banking, there has been a lot of progress in the past 10 years. In China, voluntary blood donation went from 45% of donations in 2000 to 91.3% in 2004. Malaysia, China and India reached 100% screening of donated blood for HIV by the year 2000. Data collected from 178 WHO Member States showed that the number of tests not being performed for the four main markers of infection (HIV, hepatitis B virus, hepatitis C virus, and syphilis) decreased from 13 million in 1998-1999 to 6 million in 2000-2001.

National blood donations: The WHO has proposed a goal for countries to collect 100% of their blood donations from volunteer donors. As of 2004, 51 of the member countries in the World Health Organization have been able to reach this goal. In the United States, monetary reimbursement for blood donation is only given to patients who undergo plasmaphoresis.

The main program used in the United States to increase blood donations is blood drives. The United States also has certain days or periods of time dedicated to donating blood, such as National Blood Donor Month in January (supported by the American Red Cross, the American Association of Blood Banks, and America's Blood Centers). Valentine's Day (February 14th) is also National Donor Day; it is supported by Saturn car retailers and by America's Blood Centers. June 14th is Worldwide Donor Day in honor of Nobel Prize winner Karl Landsteiner, who is credited with discovering the ABO system of blood classification.

Public opinion and beliefs often encourage Americans to donate blood. Donors are also persuaded to participate at blood drives through the offering of non-monetary incentives, such as paid time off from work, health screenings, and complementary T-shirts.


This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

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