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In the US, the collection, storage, and transport of blood and its components are standardized and regulated by the FDA, the 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.
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Table 1
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| Some Reasons for Blood Donation Deferral or Denial |
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Reason
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Donation Outcome
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Comment
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AIDS or participation in high-risk activity, homosexuality in males
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Denial
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High-risk activity such as IV drug use and sexual intercourse with a person with HIV
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Anemia
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Deferral
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Donation permitted after anemia resolves
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Bovine insulin use
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Denial
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People who have used bovine insulin since 1980: Ineligible to donate
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Cancer
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Denial
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Some people with mild, treatable forms (eg, small skin cancers): Possibly able to donate
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Certain drugs
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Deferral
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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
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Certain vaccinations
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Deferral
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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
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Congenital bleeding disorder
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Denial
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Exposure to hepatitis
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Deferral
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Wait 12 mo after possible exposure
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Hepatitis
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Denial
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Ineligible to donate if ever diagnosed with viral hepatitis
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Hypertension
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Deferral
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Defer donation until BP is controlled
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Malaria or exposure to malaria
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Deferral
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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
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Military personnel residing on US bases in Europe
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Denial
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UK, Germany, Belgium, Netherlands: ≥ 6 mo between 1980 and 1990
Elsewhere in Europe: ≥ 6 mo between 1980 and 1996
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Pregnancy
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Deferral
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Wait 6 wk after giving birth
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Severe asthma
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Denial
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Severe heart disease
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Denial
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Stay in UK or Europe
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Denial
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UK: Cumulative stay of > 3 mo between 1980 and 1996
Europe: Cumulative stay of ≥ 5 yr since 1980
France: Cumulative stay of > 5 yr since 1980
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Tattoo
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Deferral
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Wait 12 mo
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Transfusion
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Deferral
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Wait 12 mo
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Denial
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Recipients of any blood product between 1980 and the present in the UK
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*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.
†Other live-attenuated viral or bacterial vaccines may be deferred 2 or 4 wk, depending on the vaccine.
UK = United Kingdom.
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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 the preferred method of transfusion when conditions permit. In the 2 to 3 wk preceding elective surgery, up to 3 or 4 units of whole blood or packed RBCs are collected, and the patient is given iron supplements. 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).
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Table 2
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| Infectious Disease Transmission Testing |
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Infectious Agent
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Type of Testing
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Hepatitis B core
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Antibody testing
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Hepatitis B surface
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Antigen testing
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Hepatitis C virus
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Nucleic acid testing and antibody testing*
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HIV
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Nucleic acid testing
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HIV-1 and HIV-2*
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Antibody testing
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Human T-cell lymphotropic viruses 1 and 2
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Antibody testing
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Syphilis
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Antigen testing
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West Nile virus
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Nucleic acid testing
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*If antibody is positive, infection is confirmed by Western blot or recombinant immunoblotting assay.
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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.
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 Du, 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 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 serum 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%. 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 serum, 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 November 2006 by Ravindra Sarode, MD
Content last modified April 2010
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