Chapter 13:
Clinical laboratory testing is an important part of a medical office. Laboratory tests are often used to provide vital information regarding the body’s functions and its ability to maintain homeostasis. When the human body is unable to maintain homeostasis, certain biological changes can alter the chemical content of blood and urine. These changes can trigger the production of antibodies or influence the size, shape, and counts of specific cells in the body. These changes are measured and compared to normal ranges or reference numbers for that particular patient. The physician utilizes specific laboratory tests, a health history, and a thorough physical examination to help make an accurate diagnosis or manage a patient’s existing condition.
The Clinical Laboratory Improvement Amendments (CLIA) were passed by Congress in 1988 and were developed to improve the quality of laboratory testing. Laboratories that are not CLIA-compliant cannot receive Medicare and Medicaid reimbursement. The amendments established quality assurance standards for all laboratories providing patient testing regardless of their location within the United States. Quality assurance requirements include written policies, employee training, documented maintenance of instruments, documented procedures, and quality control. Laboratories also must participate in proficiency testing. The Food and Drug Administration (FDA) is responsible for regulating each laboratory under CLIA guidelines the guidelines are centered on three specific categories of tests, which are based on the potential risk to the public’s health: waived, moderate complexity and provider performed microscopy tests, and high-complexity tests.
Personnel and quality assurance requirements do not apply to waived tests. Waived tests include tests approved by the FDA that a patient can perform at home, procedures with a low or insignificant risk of errors if performed incorrectly, or tests that pose little risk of harm to the patient if performed incorrectly. The following are waived tests: dipstick or tablet reagent urinalysis, fecal occult blood, ovulation testing, urine pregnancy test, blood glucose, erythrocyte sedimentation rate (ESR), hemoglobin (HGB), hematocrit (Hct), and CLIA-approved strep A tests.
Moderate-complexity tests account for approximately 75 percent of all lab tests performed today. Most of the testing takes place in physician’s office laboratories (POL). These tests include hematology and blood chemistry performed with an automated analyzer, pinworm preparation, Gram’s staining, and microscopic analysis of urine sediment. High-complexity tests are usually not performed in a POL. These tests include pap smears, blood typing, blood cross matching, and cytology testing.
Quality control measures ensure accuracy in test results through careful monitoring of testing procedures. To comply with quality control standards, the POL must follow certain procedures including calibration, control samples, reagent control, maintenance, and documentation.
Calibration of the testing equipment must be performed according to manufacturers’ guidelines. Each calibration should be recorded in a quality control log. Calibration procedures require that the equipment generate the correct results for the standards (a specimen with a known value) supplied.
Control samples are specimens with known values used prior to processing a patient sample that checks for the accuracy of the test. If the control is not within the prescribed range, the patient sample is not analyzed. Control samples can show normal and abnormal results and can generate qualitative test response (substances being tested are present or absent) or quantitative response (the concentration of a test substance is given).
Reagents are chemicals used in test procedures that will react in specific ways when exposed to certain substances. To ensure the quality of reagents, the medical assistant should keep a reagent control log.
Maintenance of the testing equipment and instruments is an important part of the laboratory and must be documented. It is best to use manufacturers’ guidelines and keep a complete record of all work performed.
Documentation of quality control depends on adherence to the procedures designed to identify problems with equipment calibration, errors in designed procedures, and defective testing supplies. Documentation of all procedures includes a log of all mentioned quality control measures and a daily workload log and reference laboratory log (specimen sent to an outside lab for testing).