Important precautions

    The desirability of discussing investigations for HIV infection with patients beforehand and of interpreting the results to them afterwards. When patients are tested for anti-HIV in a healthcare setting, permission to
collect a sample should always have been sought by the doctor and given by the patient. An exception to this is when serum residues, already irreversibly anonymised, are tested for anti-HIV as part of an epidemiological study. Such studies have become a basis for monitoring the epidemic and predicting
future trends and resource needs. They have shown, for instance, that in the UK approximately a third of the HIVinfected population (total about 30 000 in year 2000) are unaware of their infection or have not disclosed it at the time of the medical contact.
    Clotted blood for testing should be obtained by careful venepuncture without spillage or risk of inoculation accident. The needle and syringe should be disposed of safely and the blood placed in a leakproof container, properly identified, and sent by a secure route to the laboratory. PCR testing requires a fresh EDTA specimen such as commonly used for haematological investigations. Oral fluid can be collected from
the gum/tooth margin and anti-HIV detected in this fluid.

      Anti-HIV can also be detected in urine.

      The patient’s identity and the suspected diagnosis should not be exposed to public gaze, and use of numbers or codes rather than names may be preferred. However, the risk of misidentification may thereby be increased. Patient information should only be shared over the telephone between individuals who know each other, and written reports should be sent to named members of staff, under confidential cover. Positive results should be checked on a fresh newly-drawn specimen.
    The consequences of breaches of these well-tried procedures may be very serious for patients and damaging to the reputation of doctors. Because of the implications of positive laboratory findings for the health of the patient and his or her family and contacts, and for the patient’s social and professional life, a high
level of competence and sensitivity is to be expected from all who are concerned in instigating investigation for HIV infection. Testing patients without their informed consent is unacceptable.

    Laboratory tests for HIV have increased understanding of AIDS and greatly facilitated diagnosis, management, treatment and control measures. However, to derive most benefit from them and do least harm, tests must be used wisely, with proper regard to all the possible consequences for those who are being
tested. Any changes to what are now well-established procedures must be carefully considered, piloted, evaluated for costeffectiveness, and, if introduced, periodically audited to ensure that they are yielding the benefits promised.