Screening

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," or from IV drug users or recent immigrants from certain nations with high rates of HIV infection. While the inclusion of homosexual/bisexual men on the prohibited list has created some controversy, the FDA & Red Cross cite the public policy need to protect the blood supply from HIV & similar diseases as justification for the ban. 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 Creutzfeld-Jacob Disease (vCJD): persons who have spent long periods of time in countries where "mad cow disease" is found , 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, such person is not eligible to donate; if a person spent time that adds up to three months or more in any country within the United Kingdom, they are indefinitely deferred.

When a donor arrives at a donation site, they typically fill 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, drug use (recreational or performance enhancing), residency abroad, recent international travel, and sexual history. Answers are associated with the donor's blood, but not name, to provide anonymity.

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.

Additionally, the donor may indicate to not use their blood but still go through the blood drawing process, again to protect the individual's medical privacy. All blood is later tested for diseases including STDs. If a disease is found, the donor will be notified and their blood discarded. It is discouraged for individuals to use blood donation for the purpose of anonymous STD screening.

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 a vein. 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. Typically, around 500 millilitres, about a pint, is drawn during the blood donation process.

Apheresis

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.

Recovery

Storage

Baby Donors

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

Complications

During or shortly after the donation, hypovolemia may occasionally lead to a drop in blood pressure with some donors experiencing light-headedness 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 further replenish blood volume, 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 Blood_donation_bruise.jpg in the weeks afterwards.

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

Benefits

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

Autologous donation

See also

• List of blood donation agencies
• Blood transfusion
• Plateletpheresis

References