Viral cultures either are not available or can be disproportionately expensive in relation to the potential benefit, because effective antiviral treatment is not available for most organisms. For these reasons, viral antibody tests are used to determine exposure to and existing infections with certain viruses that are difficult to culture, or they are used to screen donors before blood donation or organ transplantation (Table 3-13).

Because many types of tests can be performed, requests for viral antibody tests must be specific and include enough clinical information to permit selection of the appropriate study. A request for "viral studies" is meaningless. Antibody assays for detection of some specific disease entities, although included in Table 3-13, are outlined and discussed in the next section. They include infectious mononucleosis, hepatitis, and AIDS tests.

• Infectious Mononucleosis Tests
• Hepatitis Tests
• Acquired Immunodeficiency Syndrome Tests

• In general, lack of exposure to the virus yields a negative test result. Reference values vary with the type of viral antibody test. The laboratory performing the test should be consulted.

• Suspected AIDS or exposure to human immunodeficiency virus (HIV)
• Retrospective confirmation of viral infection
• Determination of immunity to rubella in women of childbearing age
• Confirmation of exposure to rubella in early pregnancy
• Suspected herpes encephalitis
• Determination of immunity to chickenpox in children with leukemia, because this infection may be fatal in such children
• Identification of asymptomatic carriers of cytomegalovirus (CMV)
• Monitoring of the course of prolonged viral disease
• Monitoring of mothers and neonates for exposure to viral infections that may cause congenital disease in the newborn infant (usually done by the toxoplasmosis, other infections, rubella, CMV infection, and herpes simplex [TORCH] test; see Table 3-13)

Nursing Care Before the Procedure

Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I).

A venipuncture is performed and the sample collected in a red-topped tube. The sample must be handled gently to avoid hemolysis and transported promptly to the laboratory.

Nursing Care After the Procedure

Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample.

• Women of childbearing age with low rubella titers should be appropriately immunized.
• Abnormal test results, complications, and precautions: Response is dependent on the type of viral antibody test and the specific infectious process identified in Table 3-13. See the specific tests that follow for nursing implications related to aftercare and observations.