In the US, the collection, storage, and transport of blood and its components are standardized and regulated by the FDA, the American Association of Blood Banks (AABB), and sometimes state or local health authorities. Donor screening includes an extensive questionnaire and health interview; measurement of temperature, heart rate, and BP; and Hb determination. Some potential donors are deferred either temporarily or permanently (see Table 1: Transfusion Medicine: Some Reasons for Blood Donation Deferral or Denial). Criteria for deferral protect prospective donors from possible ill effects of donation and recipients from disease. Donations are limited to once every 56 days. With rare exceptions, blood donors are unpaid. (See also the American Red Cross for information regarding donor eligibility.)

Table 1
PrintOpen table in new window
Some Reasons for Blood Donation Deferral or Denial Reason Donation Outcome Comment AIDS or participation in high-risk activity, homosexuality in males Denial High-risk activity such as IV drug use and sexual intercourse with a person with HIV Anemia Deferral Donation permitted after anemia resolves Bovine insulin use Denial People who have used bovine insulin since 1980: Ineligible to donate Cancer Denial Some people with mild, treatable forms (eg, small skin cancers): Possibly able to donate Congenital bleeding disorder Denial — Drugs (selected) Deferral Waiting period depends on drug: Finasteride: Defer for 1 mo after last dose Isotretinoin: Defer for 1 mo after last dose Dutasteride: Defer for 6 mo after last dose Acitretin: Defer for 3 yr after last dose Etretinate: Defer indefinitely Exposure to hepatitis Deferral Wait 12 mo after possible exposure Hepatitis Denial Ineligible to donate if ever diagnosed with viral hepatitis Hypertension Deferral Defer donation until BP is controlled Malaria or exposure to malaria Deferral Wait 3 yr after treatment for malaria or living in an area in which malaria is endemic; wait 12 mo after visit to an area in which malaria is endemic Military personnel residing on US bases in Europe Denial UK, Germany, Belgium, Netherlands: ≥ 6 mo between 1980 and 1990 Elsewhere in Europe: ≥ 6 mo between 1980 and 1996 Pregnancy Deferral Wait 6 wk after giving birth Severe asthma Denial — Severe heart disease Denial — Stay in UK or Europe Denial UK: Cumulative stay of > 3 mo between 1980 and 1996 Europe (except France): Cumulative stay of ≥ 5 yr since 1980 France: Cumulative stay of > 5 yr since 1980 Tattoo Deferral Wait 12 mo Transfusion Deferral Wait 12 mo Denial Recipients of any blood product between 1980 and the present in the UK Vaccinations (selected) Deferral Waiting period depends on vaccination: Toxoids or synthetic or killed viral, bacterial, or rickettsial vaccines* in symptom-free and afebrile donors: No deferral Measles, mumps, polio (Sabin), or typhoid (oral) vaccines†: Defer for 2 wk Rubella or varicella vaccines†: Defer for 4 wk *These vaccines include anthrax, cholera, diphtheria, hepatitis A, hepatitis B, influenza, Lyme disease, paratyphoid, pertussis, plague, pneumococcal polysaccharide, polio (Salk), Rocky Mountain spotted fever, tetanus, and typhoid injection. †Recipients of other live-attenuated viral or bacterial vaccines may be deferred 2 or 4 wk, depending on the vaccine. UK = United Kingdom. Some Reasons for Blood Donation Deferral or Denial Reason Donation Outcome Comment AIDS or participation in high-risk activity, homosexuality in males Denial High-risk activity such as IV drug use and sexual intercourse with a person with HIV Anemia Deferral Donation permitted after anemia resolves Bovine insulin use Denial People who have used bovine insulin since 1980: Ineligible to donate Cancer Denial Some people with mild, treatable forms (eg, small skin cancers): Possibly able to donate Congenital bleeding disorder Denial — Drugs (selected) Deferral Waiting period depends on drug: Finasteride: Defer for 1 mo after last dose Isotretinoin: Defer for 1 mo after last dose Dutasteride: Defer for 6 mo after last dose Acitretin: Defer for 3 yr after last dose Etretinate: Defer indefinitely Exposure to hepatitis Deferral Wait 12 mo after possible exposure Hepatitis Denial Ineligible to donate if ever diagnosed with viral hepatitis Hypertension Deferral Defer donation until BP is controlled Malaria or exposure to malaria Deferral Wait 3 yr after treatment for malaria or living in an area in which malaria is endemic; wait 12 mo after visit to an area in which malaria is endemic Military personnel residing on US bases in Europe Denial UK, Germany, Belgium, Netherlands: ≥ 6 mo between 1980 and 1990 Elsewhere in Europe: ≥ 6 mo between 1980 and 1996 Pregnancy Deferral Wait 6 wk after giving birth Severe asthma Denial — Severe heart disease Denial — Stay in UK or Europe Denial UK: Cumulative stay of > 3 mo between 1980 and 1996 Europe (except France): Cumulative stay of ≥ 5 yr since 1980 France: Cumulative stay of > 5 yr since 1980 Tattoo Deferral Wait 12 mo Transfusion Deferral Wait 12 mo Denial Recipients of any blood product between 1980 and the present in the UK Vaccinations (selected) Deferral Waiting period depends on vaccination: Toxoids or synthetic or killed viral, bacterial, or rickettsial vaccines* in symptom-free and afebrile donors: No deferral Measles, mumps, polio (Sabin), or typhoid (oral) vaccines†: Defer for 2 wk Rubella or varicella vaccines†: Defer for 4 wk *These vaccines include anthrax, cholera, diphtheria, hepatitis A, hepatitis B, influenza, Lyme disease, paratyphoid, pertussis, plague, pneumococcal polysaccharide, polio (Salk), Rocky Mountain spotted fever, tetanus, and typhoid injection. †Recipients of other live-attenuated viral or bacterial vaccines may be deferred 2 or 4 wk, depending on the vaccine. UK = United Kingdom.

In standard blood donation, about 450 mL of whole blood is collected in a plastic bag containing an anticoagulant preservative. Whole blood or packed RBCs preserved with citrate-phosphate-dextrose-adenine may be stored for 35 days. Packed RBCs may be stored for 42 days if an adenine-dextrose-saline solution is added.

Autologous donation, which is use of the patient's own blood, is less preferred as a method of transfusion. When done before elective surgery, up to 3 or 4 units of whole blood or packed RBCs are collected in the 2 to 3 wk preceding surgery. The patient is then given iron supplements. Such elective autologous donation may be considered when matched blood is difficult to obtain because the patient has made antibodies to red cell antigens or has a rare blood type . Special blood salvage procedures are also available for collecting and autotransfusing blood shed after trauma and during surgery.

Pretransfusion Testing

Donor blood testing includes ABO and Rh₀(D) antigen typing, antibody screening, and testing for infectious disease markers (see Table 2: Transfusion Medicine: Infectious Disease Transmission Testing).

Table 2
PrintOpen table
Infectious Disease Transmission Testing Infectious Agent Type of Testing Hepatitis B core Antibody testing Hepatitis B surface Antigen testing Hepatitis C virus Nucleic acid testing and antibody testing* HIV Nucleic acid testing HIV-1 and HIV-2* Antibody testing Human T-cell lymphotropic viruses 1 and 2 Antibody testing Treponema pallidum (syphilis) Antigen testing West Nile virus Nucleic acid testing *If antibody test is positive, infection is confirmed by Western blot or recombinant immunoblotting assay.

Compatibility testing tests the recipient's RBCs for antigens A, B, and Rh₀(D); screens the recipient's plasma for antibodies against other RBC antigens; and includes a cross-match to ensure that the recipient's plasma is compatible with antigens on donor RBCs. Compatibility testing is done before a transfusion; however, in an emergency, testing is done after releasing blood from the blood bank. It can also help in diagnosing transfusion reactions.

ABO typing of donor and recipient blood is done to prevent transfusion of incompatible RBCs (see Fig. 1: Transfusion Medicine: Compatible RBC types.). As a rule, blood for transfusion should be of the same ABO type as that of the recipient. In urgent situations or when the correct ABO type is in doubt or unknown, type O Rh-negative packed RBCs (not whole blood—see Transfusion Medicine: Acute hemolytic transfusion reaction (AHTR) for Acute Hemolytic Transfusion Reaction), which contains neither A nor B antigens, may be used for patients of any ABO type.

Fig. 1
Compatible RBC types.

Rh typing determines whether the Rh factor Rh₀(D) is present on (Rh-positive) or absent from (Rh-negative) the RBCs. Rh-negative patients should always receive Rh-negative blood except in life-threatening emergencies when Rh-negative blood is unavailable. Rh-positive patients may receive Rh-positive or Rh-negative blood. Occasionally, RBCs from some Rh-positive people react weakly on standard Rh typing (weak D, or D^u, positive), but these people are still considered Rh-positive.

Antibody screening for unexpected anti-RBC antibodies is routinely done on blood from prospective recipients and prenatally on maternal specimens. Unexpected anti-RBC antibodies are specific for RBC blood group antigens other than A and B [eg, Rh₀(D), Kell (K), Duffy (Fy)]. Early detection is important because such antibodies can cause serious hemolytic transfusion reactions or hemolytic disease of the newborn (see Perinatal Hematologic Disorders: Hemolysis), and they may greatly complicate compatibility testing and delay procurement of compatible blood.

Indirect antiglobulin testing (the indirect Coombs' test) is used to screen for unexpected anti-RBC antibodies. This test may be positive in the presence of an unexpected blood group antibody or when free (non-RBC–attached) antibody is present in autoimmune hemolytic anemias (see Anemias Caused by Hemolysis: Autoimmune Hemolytic Anemia). Reagent RBCs are mixed with the patient's plasma or serum, incubated, washed, tested with antihuman globulin, and observed for agglutination. Once an antibody is detected, its specificity is determined. Knowing the specificity of the antibody is helpful for assessing its clinical significance, selecting compatible blood, and managing hemolytic disease of the newborn.

Direct antiglobulin testing (the direct Coombs' test) detects antibodies that have coated the patient's RBCs in vivo. It is used when immune-mediated hemolysis is suspected. Patients' RBCs are directly tested with antihuman globulin and observed for agglutination. A positive result, if correlated with clinical findings, suggests autoimmune hemolytic anemia, drug-induced hemolysis, a transfusion reaction, or hemolytic disease of the newborn.

Antibody titration is done when a clinically significant, unexpected anti-RBC antibody is identified in the plasma of a pregnant woman or in a patient with cold autoimmune hemolytic anemia (see Anemias Caused by Hemolysis: Autoimmune Hemolytic Anemia). The maternal antibody titer correlates fairly well with the severity of hemolytic disease in the incompatible fetus and is often used to guide treatment in hemolytic disease of the newborn along with ultrasonography and amniotic fluid study.

The addition of a cross-match to ABO/Rh typing and antibody screening increases detection of incompatibility by only 0.01%. Therefore, many hospitals are doing computerized electronic cross-matches rather than physical cross-matches in patients who have negative antibody screening. If the recipient has a clinically significant anti-RBC antibody, donor blood is restricted to RBC units negative for the corresponding antigen; further testing for compatibility is done by combining recipient plasma , donor RBCs, and antihuman globulin. In recipients without clinically significant anti-RBC antibodies, an immediate spin cross-match, which omits the antiglobulin phase, confirms ABO compatibility.

Emergency transfusion is done when not enough time (generally < 60 min) is available for thorough compatibility testing because the patient is in hemorrhagic shock. When time permits (about 10 min is needed), ABO/Rh type-specific blood may be given. In more urgent circumstances, type O RBCs are transfused if the ABO type is uncertain, and Rh-negative blood is given if the Rh type is uncertain.

“Type and screen” may be requested in circumstances not likely to require transfusion, as in elective surgery. The patient's blood is typed for ABO/Rh antigens and screened for antibodies. If antibodies are absent and the patient needs blood, ABO/Rh type specific or compatible RBCs may be released without the antiglobulin phase of the cross-match. If an unexpected antibody is present, full testing is required.

Last full review/revision July 2012 by Ravindra Sarode, MD