Testing Categories

Diagnostic testing that is not performed within a traditional laboratory is called waived testing by The Joint Commission (TJC, formerly known as the Joint Commission on Accreditation of Healthcare Organizations [JCAHO]). The Clinical Laboratory Improvement Acts of 1988 (CLIA ’88) subjects all clinical laboratory testing to federal regulation and inspection. According to CLIA ’88, test procedures are grouped into one of four following categories:

Test complexity is determined by criteria that assess knowledge, training, reagent and material preparation, operational technique, QC-QA characteristics, maintenance and troubleshooting, and interpretation and judgment. Any over-the-counter test approved by the U.S. Food and Drug Administration (FDA) is automatically placed into the “waived” category. POCT falls within the “waived” or “moderately complex” category.

Quality Control Standards

All laboratory testing must meet the same quality standards regardless of where it is performed. State and city governments may enact mandatory regulations, including qualifications of personnel performing the test, which may be more (but not less) stringent than federal regulations. Voluntary participation in QA programs is also available.

The Centers for Disease Control and Prevention (CDC; www.cdc.gov) has invited providers to participate in a new performance evaluation program (HIV Rapid Testing MPEP) that offers the external evaluation of rapid tests for human immunodeficiency virus (e.g., OraQuick Rapid HIV-1 Antibody Test) and other licensed tests (e.g., MedMira Reveal Rapid HIV-1 Test).

Ultimate responsibility and control of POCT reside within the CLIA-certified laboratory and require a minimum of one laboratory staff member to be responsible for each POCT program. Written policies and procedures must be available to all laboratory personnel for patient preparation, specimen collection and preservation, instrument calibration, policies for QC and remedial actions, equipment performance evaluations, procedures for test performance, result report, and recording. The greatest source of error is preanalytic error, such as patient identification and specimen collection.

Non–Instrument-Based Testing

In immunology and serology testing, most POCT testing is done by manual rapid test methods, such as pregnancy testing. More rapid tests are being developed for the identification of infectious organisms, such as group A streptococci and HIV, in emergency rooms, in hospital settings, and even at home. Numerous POCT tests are referenced throughout this book in various chapters. The card pregnancy test is presented as an example in this chapter.

The OSOM Card Pregnancy Test (Fig. 9-1) is a solid-phase, sandwich-format, immunochromatographic assay for the qualitative detection of human chorionic gonadotropin (hCG).

Urine is added to the sample well and the sample migrates through reaction pads, where hCG, if present in the sample, binds to a monoclonal anti-hCG dye conjugate. The sample then migrates across a membrane toward the “results window,” where the labeled hCG complex is captured at a test line region containing immobilized rabbit anti-hCG. Excess conjugate will flow past the test line region and will be captured at a control line region containing an immobilized antibody directed against the anti-hCG dye conjugate (with or without hCG complexed to it).

The appearance of two black bands in the results window, one at T (test) and the other at C (control), indicates the presence of hCG in the sample. If a detectable level of hCG is not present, only the control band will appear in the results window.

See website for the procedural protocol.

Chapter Highlights