Information about Blood Donation

Blood donation is a process by which a blood donor voluntarily has blood drawn for storage in a blood bank, generally for subsequent use in a blood transfusion.



Blood donations may be scheduled at local centres, or at times a "blood drive" will occur. These are events where a blood bank or other blood collecting organization will set up in a convenient location—such as a shopping centre, large employer, university, high school, or a local church—for people to stop in without appointment during their daily routine to donate blood. Sometimes a bloodmobile is used to run a blood drive. Usually a modified recreational vehicle, it is an easy place to run a blood drive because it is already set up for the process of blood donation.

Process

The process of giving blood involves screening the donor, the actual donation, and a brief recovery period. This applies to both whole blood donations and plasmapheresis, or donating only one's plasma (see "Donation" below).

Preparation

In the days prior to donating blood, it is important that donors prepare themselves for a process that can temporarily weaken the body. Donors should check their local blood bank's guidelines, as requirements and recommendations vary. Many blood banks recommend that potential donors drink extra water and fluids before donating.^[1][2][3] It may be advisable to avoid caffeinated beverages before donation.<ref name="usarctips" /> Eating well is also important, and can reduce the risk of reactions to donation.<ref name="australiatips" /><ref name="canadatips" /> Eating foods high in iron (which has many dietary sources) is also a good idea; low hemoglobin levels may make a donor temporarily ineligible.<ref name="australiatips" /><ref name="canadatips" /><ref name="usarctips" /> This is especially true for women who have menstruated recently, because of iron loss in the menses.^[4] Some countries require donors to observe a limited or full fast before donation because of specific screening methods; in particular, some countries will discard blood taken too soon after a fatty meal. High levels of lipemia (essentially fat in the blood) can interfere with infectious disease testing.

Screening

Western countries typically impose screening for blood donor candidates. In the past, it was the practice in America and other countries to separate blood donations on the basis of race, ethnicity, or religion, or to exclude certain groups from the donor pool on those bases. Currently, in the United States, these practices have been eliminated, and donor attributes are considered only in terms of their likelihood to affect the probability of transmission of disease. All blood products in the U.S. are labeled as coming from either "paid" or "volunteer" donors, with paid units being more likely to transmit infection. (Several other countries avoid paid donations altogether for this reason.) Other donor characteristics are also taken into account: starting in 1985, the American Red Cross and Food and Drug Administration policies prohibit accepting blood donations from gay/bisexual men, specifically from any "male who has had sex with another male since 1977, even once,"^[5] or from IV drug users or recent immigrants from certain nations with high rates of HIV infection. The inclusion of men who have sex with men on the prohibited list has created some degree of controversy [1]; the FDA & Red Cross cite the public policy need to protect the blood supply from HIV & similar diseases as justification for the ban, while others believe the ban to be discriminatory, since sexually active heterosexuals are not categorically banned and all donated blood is screened. Policies vary in other countries; for instance, Australia formerly had a similar ban, but now only prohibits donating blood within one year after male-male sex (longer than the typical window period for HIV blood screening tests performed on donated blood).

Similarly important donor eligibility requirement in the US is related to concerns about variant Creutzfeldt-Jakob Disease (vCJD): persons who have spent long periods of time in countries where "mad cow disease" is found^[6] are not eligible to donate. As part of the screening interview, blood donors are questioned about past residency in countries on the exclusion list, tracing back as far as 1980. The list of countries of residence that may disqualify a potential donor includes most of Western Europe (with stronger restrictions on those with past residence in the United Kingdom), Turkey, and all of Eastern Europe except Russia, Ukraine, Belarus, and the Baltic countries (those formerly part of the Soviet Union). From 1980 through 1996, if a person visited or resided in country on the exclusion list for a time that adds up to five years or more, the person is not eligible to donate; if a person spent time that adds up to three months or more in the United Kingdom, they are indefinitely deferred. This set of rules affects members of the US Armed Forces and others, who lived at least six months in certain European countries or 3 months in the United Kingdom from 1980 to 1996, who are therefore prohibited from donating blood.^[7] A similar policy with regard to vCJD applies in France, Quebec and in the rest of Canada.^[8]

When a donor arrives at a donation site, he or she typically fills out a consent form as well as answer an extensive questionnaire to help determine their eligibility. Questions include the donors' age, weight, most recent donation, current health, and various risk factors such as tattooing, illicit use of intravenous drugs (recreational or performance enhancing), residency abroad, recent international travel, and sexual history. In some countries, answers are associated with the donor's blood, but not name, to provide anonymity; in others such as the United States, names are kept to create deferral lists.

Often the blood hemoglobin concentration will be checked next, typically performed by a phlebotomist. While various tests exist, the most common ones are:

• hematocrit: done in some places. requires a centrifuge. A measurement of no less than 38% allows donation to continue.
• colorimetric hemoglobin test using a hemoglobin photometer: a machine-read result from a chemical reaction on a testing strip.
• copper sulfate screening test (aka "float test"): measures the specific gravity of the donor's blood by placing a drop into a copper sulfate solution. The solution is calibrated so that a hemoglobin concentration of in >12.5 g/dl (the cut-off in the U.S. for donation) sinks.

All blood is later tested for diseases, including STDs. If the test is positive, the donor will be notified and their blood discarded. The tests used are high-sensitivity screening tests and no actual diagnosis is made. Some of the test results are later found to be false positives using more specific testing. Individuals are discouraged from using blood donation for the purpose of anonymous STD screening because a false negative could mean the disease would be passed to someone else. Blood may also be tested for additional infectious diseases such as West Nile Virus, when and where these diseases are prevalent.^[9]

Donated blood is tested by many methods, and a typical screening panel includes most of the tests below:

• Antibody to Hepatitis B core "anti-HBc"
• Hepatitis B Surface Antigen "HBsAg"
• Nucleic acid testing by Transcription Mediated Amplification (TMA) or Polymerase Chain Reaction (PCR) for Hepatitis B "HBV-NAT"
• Antibody to Hepatitis C "anti-HCV"
• Nucleic acid testing for HCV "HCV-NAT"
• Alanine Transaminase "ALT" (this test is used to check for liver problems which may be a sign of hepatitis and has been phased out as tests for hepatitis have improved)
• Antibody to HIV types 1 and 2 "Anti-HIV1/2"
• Nucleic acid for HIV "HIV-NAT"
• Antibody to HIV p24 antigen (this test has been mostly replaced by HIV NAT)
• Antibody to Human T-Lymphotrophic Virus I/II "anti-HTLV"
• Nucleic acid testing for West Nile Virus "WNV-NAT"
• Antibody to Chagas Disease
• Serologic test for syphilis "RPR" or "STS"
• Antibody to Cytomegalovirus "anti-CMV"
• Atypical red cell antigen screening
• Blood typing

Donation

The blood donation itself happens next. The donor lies supine on a cushioned bench and extends an arm. The inner elbow is disinfected, and a cannula is inserted into the medial antecubital vein. A large bore needle is used to prevent hemolysis. The donor often has a tourniquet wrapped around his or her arm, or may be prompted to squeeze a ball repeatedly, to help speed the process. Blood flows from the vein, through the needle and a tube, and into a special collection bag which is placed on a small scale to measure the amount of blood withdrawn. After the bag is sufficiently filled, several test tubes are drawn from the same needle to be used for disease detection. Typically, around 450 millilitres, about a U.S. pint, is drawn during the blood donation process. The blood is stored in a blood bag which contains acid citrate dextrose, an anticoagulant which prevents blood clotting and preserves the blood for long periods of time.

Apheresis

Rather than donating whole blood, a donor sometimes has the option to donate only some blood components while retaining others. This process is known as apheresis, and is more involved, time consuming, and requires more specialized equipment. The benefit is that more of the desired components can be concentrated and removed, and the donor is usually able to donate significantly more frequently than if whole blood had been removed. In some cases, the usefulness of the removed components is not as sensitive to blood type considerations. Additionally, donors with high platelet counts can be divided in what is referred to as a "split" and a single donation can be used for two future transfusions.

The typical method of apheresis is to draw whole blood from the donor, then centrifuge the blood to separate its components (see apheresis for more information). The desired components (e.g. platelets, plasma) are removed and then the remaining components are returned to the donor.

"Double red"

A recent innovation in apheresis is the "double red" donation, which extracts two units of red blood cells instead of the single unit of an ordinary whole-blood donation. This provides several benefits to both the donor and the blood bank. The donor can make the same red-cell contribution with half the visits, and the return of plasma to the body leaves the donator better hydrated. The process takes somewhat longer than a standard donation (about 35-45 minutes), but is much shorter than a regular apheresis visit. The blood bank receives twice the usual red-cell donation in each visit. Because more red cells are removed from the circulatory system, donors must meet some additional health requirements for a double-red donation.^[10][11][12]

Recovery

Once the donation is complete, the donor is given a bandage or gauze to stop further blood flow and is normally allowed to leave. Beverages and snacks may be provided to restore blood volume and blood sugar, and to settle the stomach. Often donors are encouraged to sit down for a few minutes to return to normality, as lightheadedness and faintness may occur. In some countries, stickers are worn by donors to show the donor's pride and to encourage others to give. The entire process, from screening through recovery has a variable time, it can take from some fifteen minutes to about one hour. The actual blood donation takes between four and fifteen minutes for whole blood donation. Donors are discouraged from heavy exercise or lifting for several hours.^[13] Plasma volumes will return to normal in around 24 hours, while red blood cells are replaced by bone marrow into the circulatory system within about 3-5 weeks, and lost iron replaced over 6-8 weeks. This recovery process can be accelerated by eating foods high in complex carbohydrates, iron, and other trace minerals. Due to the timeframe required for iron replacement, donors are eligible to donate whole blood approximately eight to twelve weeks after the previous donation, the exact period varying by country. In the USA, Whole Blood donations can be taken every 56 days, the waiting period for the "double red" apheresis donors is 112 days.^[11][12] Donors can donate far more frequently if taking iron supplements but this is generally only done under medical supervision.

Storage

Cryopreservation of red blood cells is done to store special, rare red blood cells for up to 10 years. The ten year outdate is not based on any specific research, it was chosen arbitrarily, and some blood banks maintain truly rare red blood cells past the ten years because there are no alternative sources. The cells are first incubated in a 40% glycerol solution which acts as a cryoprotectant ("antifreeze") within the cells. The units are then placed in special sterile containers in a deep freezer at less than -60 °C.

Donors for babies

A tiny percentage of adults may donate blood to small children in emergency rooms, newborn babies, and fetuses. To ensure the safety of blood transfusion to pediatric patients, including those in whom the immune systems are not fully developed, hospitals are taking every precaution to avoid infection and prefer to use specially tested pediatric blood units that are guaranteed negative for cytomegalovirus (CMV),^[14] because the consequences of CMV infection for newborns or low weight infants may be severe or even fatal. Additionally, for pediatric patients with certain disorders or in emergency, when there is no time to perform crossmatching, only O/Rh negative blood can be used for neonatal transfusion.^[15] Due to these specific restrictions, to be recognized as a baby donor an adult must test negative for cytomegalovirus. Since only 7% of US adults are O-negative and as few as 15% of adults do not carry CMV, only 1% of adults may qualify as baby donors. Other restrictions (body weight, HIV status, vCJD, etc. ) reduce the fraction of potential baby donors to less than 1 in 200. If an adult was not exposed to measles, mumps, rubella, or chicken pox, that amplifies the person's status as a baby donor.

Newborn babies that require multiple surgeries often need up to 20 units of blood in their first few weeks.

Complications

The finger prick and needle insertion typically cause only minor discomfort. Phlebotomists may, however, experience difficulties in obtaining enough blood from some donors.

During or shortly after the donation, hypovolemia may occasionally lead to a drop in blood pressure, with some donors experiencing light-headedness, nausea, or fainting. In some cases this may necessitate cancelling the donation, restoring blood volume with an intravenous infusion, or placing the donor in a Trendelenburg position (on a stretcher tilted "legs up"). Beverages may be given to replenish blood volume further, and the donor may have to remain in a horizontal position for a while under monitoring. Most blood banks encourage donors to rest for several minutes after donation (often while eating and drinking) to let them adjust to the loss of blood and reduce the risk of these problems.

In less than 1% of cases, improperly inserting the needle is followed by bruising of the arm in the weeks afterwards.^[16]

Negative medical reactions to blood donation are rare, and blood bank staff are trained to handle them.

Benefits

Donating blood may reduce the risk of heart disease for men^[17] and stimulate the generation of red blood cells.

In patients prone to iron overload (e.g. due to hemochromatosis), blood donation prevents the accumulation of iron. However, at this time the American Red Cross does not accept people with hemochromatosis to donate blood for other people.^[18] On the other hand, the Australian Red Cross Blood Service does accept blood from hemochromatosis as they recognise that it is a genetic disorder that does not affect the safety of the blood. In the US, a blood bank must allow patients with hereditary hemochromatosis to receive therapeutic phlebotomies (i.e. a blood donation) for free regardless of whether or not the blood can be used for transfusion. This is done to remove any financial incentive for therapeutic donors to lie about their health in order to be eligible, since normally they would pay for the phlebotomy.^[19]

Anecdotally, elderly people in good health have reported feeling invigorated by giving blood on a regular basis.

Other incentives are sometimes added by employers, usually time off for the purposes of donating. Blood centers will also sometimes add incentives such as assurances that donors would have priority during shortages or other programs. Other incentives may include prize drawings for donors and rewards for organizers of successful drives, especially during the summer months when blood is often in short supply. Very few blood donors (other than plasmapheresis donors) are paid for donating, as this again leads to concerns about donors being less than truthful about their health in order to receive a financial benefit.

The majority of blood donors, however, donate as an act of charity and do not expect to receive any direct benefit from the donation.

Autologous donation

A person who anticipates the need for a blood transfusion at a later date (usually because of scheduled surgery) may make an autologous donation, in which their blood is stored and later transfused back into its original donor. Besides ensuring the availability of compatible blood (especially important for patients with rare blood types), this procedure also eliminates the risk of disease transmission from infected donors. Autologous donation is sometimes done by the hospital instead of a community blood bank. Eligibility requirements are relaxed for autologous donors, as the blood is not used for anyone else. Generally, any patient who is eligible for elective surgery is eligible for autologous donations, though there are some exceptions, particularly history of heart disease.

See also

• List of blood donation agencies
• Blood transfusion
• Plateletpheresis
• Bloodletting

References

External links

• US Blood Donation Campaign - home of the Red Defender
• LifeSource - Blood Donation Centers in Illinois
• Blood Donation and Processing
• FAQs and donor information from the American Red Cross
• USA Directory of Blood Donation Centers
• National Blood Service (England and North Wales)
• The Welsh Blood Service Gwasanaeth Gwaed Cymru (South Wales)
• Scottish National Blood Transfusion Service
• Australian Red Cross Blood Service
• Breakthrough makes all blood types universal - Joyce Howard Price, The Washington Times - April 4, 2007
• Indian Blood donors information and Blood Donation Facts
• Slovenian donors information and Blood Donation
• JMH Blood Services, Abingdon, Va. Blood bank serving Southwestern Virginia

•  • [ e] Transfusion medicine
General concepts	Apheresis  (Plasmapheresis, Plateletpheresis, Leukapheresis) - Blood transfusion - Coombs test - Cross-matching - Exchange transfusion - International Society of Blood Transfusion - Intraoperative blood salvage - ISBT 128 - Transfusion reactions
Human blood group systems  - Blood type	ABO - Chido-Rodgers - Colton - Cromer - Diego - Dombrock - Duffy - Gerbich - GIL - Hh - Ii - Indian - JMH - Kell (Xk) - Kidd - Knops - Landsteiner-Weiner - Lewis - Lutheran - MNS - OK - P - Raph - Rh - Scianna - T-Tn - Xg - Yt
Blood products	Blood donation - Blood substitutes - Cryoprecipitate - Platelets - Plasma - Red blood cells