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The medical history is an extremely important part of the selection of donors because it can reveal reasons why donation might not be wise for the donor or reasons why the donor’s blood might pose increased risk for the patient. Because most blood organizations now use the computerized self‐administered history, the interview usually takes less than 10 minutes. Many blood organizations provide the opportunity for the donor to do this online in advance. In addition to obtaining responses to these specific questions (Table 4.2), the interviewer attempts to assess whether the donor is in good general health, is not under the influence of drugs, and is able to give informed consent for the donation. The interview must occur in a setting that provides privacy for the donor. Although complete visual privacy is not always possible, visual distractions should be minimized, and the donor’s answers must not be audible to others. The interviewer reviews the response in the computer‐assisted donor history and then asks specific questions. The varied levels of computer‐assisted donor screening seem to be acceptable to donors and may decrease errors [14].

An interagency task force developed a standard donor history questionnaire (DHQ) that is approved by the FDA (https://www.fda.gov/vaccines‐blood‐biologics/guidance‐compliance‐regulatory‐information‐biologics/biologics‐guidances) and is used as a template by most blood banks. There is supplemental material for the DHQ regarding responses to each question, together with a flow chart defining need for and duration of deferral (http://www.aabb.org/tm/questionnaires/Documents/dhq/v2‐1/DHQ‐v2‐1‐Implementation‐Toolkit.pdf). The DHQ can be self‐administered by the donor or combined with direct questioning and is easily put in a computer‐assisted format. The questions designed to protect the safety of the donor include those regarding medications and whether the donor has a history of heart or lung disease, present or recent pregnancy, recent donation of blood or plasma, or bleeding condition. Questions pertaining to recipient safety include inquiry to the donor’s general health; the presence of a bleeding disorder, Chagas’ disease (although the question is not helpful) [15], or babesiosis; the injection of drugs; blood transfusion; tattoo or ear or body piercing; organ or tissue transplant; travel to areas endemic for malaria, Ebola, or Zika; recent immunizations; contact with persons with hepatitis or other transmissible diseases; ingestion of medications, especially aspirin; or previous notice of a positive test for human immunodeficiency virus/acquired immune deficiency virus (HIV/AIDS).

Individuals who have spent more than 3 months in the United Kingdom from 1980 to 1996 are deferred because of possible exposure to the causative agent of variant Creutzfeldt–Jakob disease, as are those who have spent 5 or more years in selected European countries. Based on studies in the United States and Canada, which have modified restrictions, 1–2% donor loss has been estimated because some form of this question has been included on the questionnaire [16–18].

Table 4.2 Complete list of medical history questions for blood donors.

Source: Fung MK, Eder AF, Spitalnik S, Westhoff CM, eds. Technical Manual, 19th edn. Arlington, VA: American Association of Blood Banks, 2017.

Are you

Feeling healthy and well today?

Currently taking an antibiotic?

Currently taking any other medication for an infection?

Please read the Medication Deferral List

Have you taken any medications on the Medication Deferral List in the time frames indicated? (Review the Medication Deferral List.)

Have you read the educational materials today?

In the past 48 hours,

Have you taken aspirin or anything that has aspirin in it?

Female donors: Have you been pregnant or are you pregnant now? (Males: check “I am male”)

In the past 8 weeks, have you

Donated blood, platelets, or plasma?

Had any vaccinations or other shots?

Had contact with someone who was vaccinated for smallpox in the past 8 weeks?

In the past 16 weeks, have you

Have you donated a double unit of red cells using an apheresis machine?

In the past 12 months, have you

Had a blood transfusion?

Had a transplant such as organ, tissue, or bone marrow?

Had a graft such as bone or skin?

Come into contact with someone else’s blood?

Had an accidental needle‐stick?

Had sexual contact with anyone who has HIV/AIDS or has had a positive test for the HIV/AIDS virus?

Had sexual contact with a prostitute or anyone else who takes money or drugs or other payment for sex?

Had sexual contact with anyone who has ever used needles to take drugs or steroids, or anything not prescribed by their doctor?

Male donors: Had sexual contact with another male?

Female donors: Had sexual contact with a male who had sexual contact with another male in the past 12 months?

Had sexual contact with a person who has hepatitis?

Lived with a person who has hepatitis?

Had a tattoo?

Had ear or body piercing?

Had or been treated for syphilis or gonorrhea?

Been in juvenile detention, lockup, jail, or prison for more than 72 consecutive hours?

In the past 3 years, have you

Been outside the United States or Canada?

From 1980 through 1996

Did you spend time that adds up to 3 months or more in the United Kingdom? (Review list of countries in the UK)

Were you a member of the U.S. military, a civilian military employee, or a dependent of a member of the U.S. military?

From 1980 to the present, did you

Spend time that adds up to 5 years or more in Europe? (Review list of countries in Europe.)

Receive a blood transfusion in the United Kingdom or France? (Review country lists.)

Have you ever

Female donors: Been pregnant or are you pregnant now?

Had a positive test for the HIV/AIDS virus?

Used needles to take drugs, steroids, or anything not prescribed by your doctor?

Received money, drugs, or other payment for sex?

Had malaria?

Had Chagas’ disease?

Had babesiosis?

Received a dura mater (or brain covering) graft or xenotransplantation product?

Had any type of cancer, including leukemia?

Had any problems with your heart or lungs?

Had a bleeding condition or a blood disease?

Have any of your relatives had Creutzfeldt–Jakob disease?

Potential donors who have resided in or traveled to malaria‐endemic areas are deferred for 12 months. However, most transfusion‐transmitted malaria is associated with lengthy residence in malaria‐endemic areas rather than routine or short‐term travel, especially when short‐term travel is concentrated in tourist areas that may have little or no risk [19].

Several questions related to AIDS risk behavior include whether the potential donor has had sex with anyone with AIDS risk factors, that is, given or received money or drugs for sex, had sex with another male (for males), or had sex with a male who has had sex with another male (for females). One area of inconsistency that has been eliminated involved whether males had sex with another male (MSM) at any time since 1977 (when HIV is thought to have entered humans). Previously, deferral had been indefinite, but this has been changed to 12 months to be consistent with other risk deferrals, and the reference to 1977 was eliminated. When the FDA changed this guidance regarding MSM in late 2015, it also committed to studying the effects of these changes on HIV risk in the blood supply through the Transfusion‐Transmissible Infections Monitoring System (TTIMS), a collaborative effort of the FDA, National Institutes of Health, and several major blood centers [20]. Although US data for the initial period since the changes have not yet been published, reports from Canada suggest that risk will not be greatly altered and that models used to estimate risk have been accurate [21–23]. In any case, when more data are available it may facilitate consideration of additional policy changes being tried in other countries, such as shorter (3 or 6 months) MSM deferral, or using other criteria to assess blood donor HIV risk that eliminates the MSM question.

Transfusion recipients can theoretically harbor unknown infectious agents and perpetrate the cycle of transmissible disease, and so deferral of previous transfusion recipients has been considered. In one very large study, a previous transfusion history was found in 4.2% of donors. However, transfused and nontransfused donors had a similar incidence of positive viral screening tests and other deferrable risks [24], and thus receipt of transfusions is not a deferral criterion.

The medical history is an extremely effective part of ensuring the safety of the blood supply. For instance, the implementation of questions about behavior that would put potential donors at risk for HIV infection decreased the HIV infectivity of blood in the San Francisco Bay area by 90% even before the use of the HIV screening test [25]. One concern that remains even today has been that people who have engaged in high‐risk behavior might seek to donate blood to obtain a test for HIV. In some situations, this seems to be true. Of 30 HIV‐positive blood donors in Paris, 47% had known risk behaviors and 50% admitted to having donated to obtain a test for HIV [26]. In a larger study of HIV‐seropositive blood donors, their reasons for donating in spite of having participated in behavior that placed them at risk for HIV infection included failure to read carefully or comprehend the deferral information, group pressure, a desire to be tested, and belief that the testing would identify any infected blood [27]. Despite concerns raised by this study, overall, blood donors have a lower rate of transmissible disease test results than the general population.

Occasionally, situations arise in which the donor’s physician believes that donation would be safe, but the blood bank does not accept the donor. For instance, some medications may make the individual unsuitable as a blood donor because of the condition requiring the medication, while other medications may be potentially harmful to the recipient. Many other conditions must be evaluated individually by the blood bank physician, whose assessment of conformance with FDA regulations, which consider blood a pharmaceutical, may not always coincide with another physician’s view of the health of the potential donor.