Laboratory Testing
For many people, laboratory testing is an unfamiliar environment.
All laboratory test methods must meet scientifically rigorous criteria before they can be used.
Indicators of Test Reliability
The accuracy and precision of each test method are established and are frequently monitored by the professional laboratory personnel. Although each test has its own performance measures and appropriate uses, laboratory tests are designed to be as precise, accurate, specific, and sensitive as possible.
Accuracy and Precision
Statistical measurements of accuracy and precision reveal a lab test’s basic reliability. These terms, which describe sources of variability, are not interchangeable. A test method can be precise (reliable reproducibility) without being accurate (measuring what it is supposed to measure and its true value) or vice versa.
Accuracy (Trueness)
A test method is said to be accurate when the test value approaches the absolute “true” value of the substance (analyte) being measured. Results from every test performed are compared to known “control specimens” that have undergone multiple evaluations and compared to the “gold” standard for that assay, thus analyzed to the best testing standards available.
Precision (Repeatability)
A test method is said to be precise when repeated analyses on the same sample give similar results. When a test method is precise, the amount of random variation is small. The test method can be trusted because results are reliably reproduced time after time.
Although a test that is 100% accurate and 100% precise is ideal, in practice, test methodology, instrumentation, and laboratory operations all contribute to small but measurable variations in results. The small amount of variability that typically occurs does not usually detract from the test’s value and statistically is insignificant. The level of precision and accuracy that can be obtained is specific to each test method but is constantly monitored for reliability through comprehensive quality control and quality assurance procedures.
Quality Control Laboratory testing is subject to many factors that potentially could adversely affect the integrity of the sample and prevent the timely reporting of an accurate test result. Typically these are grouped into three areas that track the sample from beginning to end of the process.
From the time a test is ordered, a chain of events is set into motion. All these steps must be done the right way to ensure that an acceptable sample arrives at the lab. The following are some of the areas where errors can occur, even though standard procedures are in place to prevent such error.
Test ordering process – the provider must order the correct test using the correct test name or code.
Analytic Activities
Many test methods use automated analyzers, thus minimizing opportunities for human error. In the past decade or so, integrated computer technology has greatly enhanced the ability to accurately and consistently manage proper specimen identification, process of specimen testing, and test result reporting. In addition, these complex instruments can incorporate surveillance systems to detect malfunctions or other discrepancies and bring them to the attention of the laboratory staff.
Once the specimen is received in the laboratory, quality assurance procedures guide and monitor all related activities and include the following:
Post-Analytic Activities
After the test is completed, the result must be delivered in a timely fashion.
For many people, laboratory testing is an unfamiliar environment.
All laboratory test methods must meet scientifically rigorous criteria before they can be used.
Indicators of Test Reliability
The accuracy and precision of each test method are established and are frequently monitored by the professional laboratory personnel. Although each test has its own performance measures and appropriate uses, laboratory tests are designed to be as precise, accurate, specific, and sensitive as possible.
Accuracy and Precision
Statistical measurements of accuracy and precision reveal a lab test’s basic reliability. These terms, which describe sources of variability, are not interchangeable. A test method can be precise (reliable reproducibility) without being accurate (measuring what it is supposed to measure and its true value) or vice versa.
Accuracy (Trueness)
A test method is said to be accurate when the test value approaches the absolute “true” value of the substance (analyte) being measured. Results from every test performed are compared to known “control specimens” that have undergone multiple evaluations and compared to the “gold” standard for that assay, thus analyzed to the best testing standards available.
Precision (Repeatability)
A test method is said to be precise when repeated analyses on the same sample give similar results. When a test method is precise, the amount of random variation is small. The test method can be trusted because results are reliably reproduced time after time.
Although a test that is 100% accurate and 100% precise is ideal, in practice, test methodology, instrumentation, and laboratory operations all contribute to small but measurable variations in results. The small amount of variability that typically occurs does not usually detract from the test’s value and statistically is insignificant. The level of precision and accuracy that can be obtained is specific to each test method but is constantly monitored for reliability through comprehensive quality control and quality assurance procedures.
Quality Control Laboratory testing is subject to many factors that potentially could adversely affect the integrity of the sample and prevent the timely reporting of an accurate test result. Typically these are grouped into three areas that track the sample from beginning to end of the process.
- Pre-Analytical is the term used to describe things that happen from the time the test is ordered to the time the sample arrives in the lab.
- Analytical is the term used to describe the things that happen during the handling and analysis of the sample in the laboratory.
- Post-Analytical is the term used to describe what happens after a result is obtained and includes how and when it is reported.
From the time a test is ordered, a chain of events is set into motion. All these steps must be done the right way to ensure that an acceptable sample arrives at the lab. The following are some of the areas where errors can occur, even though standard procedures are in place to prevent such error.
Test ordering process – the provider must order the correct test using the correct test name or code.
- Pet preparation for the test – the owner of the pet should have received appropriate instructions about diet, fasting, medications, etc. to ensure that the sample will not contain substances that interfere with the test.
- Pet identification – the person collecting the sample needs to confirm that the pet is indeed the pet on whom the test was ordered. Confirming proper identification of the pet. When you are asked to give your pet name and some other identifying information, it is to ensure that you and your sample are correctly matched. If this isn’t done when a sample is taken, make sure you check to see that your sample is identified correctly.
- Completeness of pet information – the sample must be carefully labeled with date of birth to ensure that the sample is associated with the correct pet. A hard copy requisition or electronic version must accompany the specimen and includes the tests ordered, pet name or collar tag or colour of the collar, date of birth, sex of the animal, microchip number if available.
- Specimen collection procedures – the sample must be collected in the correct type of container.
- Transport to the lab - careful handling and prompt transportation are important components to sample integrity. In addition, ambient temperatures during transport, with extremely hot or cold weather, may also have an impact on specimen integrity and must be addressed accordingly.
Analytic Activities
Many test methods use automated analyzers, thus minimizing opportunities for human error. In the past decade or so, integrated computer technology has greatly enhanced the ability to accurately and consistently manage proper specimen identification, process of specimen testing, and test result reporting. In addition, these complex instruments can incorporate surveillance systems to detect malfunctions or other discrepancies and bring them to the attention of the laboratory staff.
Once the specimen is received in the laboratory, quality assurance procedures guide and monitor all related activities and include the following:
- Instrument operations – all instruments are calibrated and tested regularly according to standard protocols that address quality control, maintenance, and operation.
- Valid test reagents – all test materials have an expiration date. The lab has routine procedures to make sure that test materials are good and have not gone past their expiration date.
- Testing personnel – laboratory personnel who perform the testing must meet certain educational and training criteria.
Post-Analytic Activities
After the test is completed, the result must be delivered in a timely fashion.
- Report sent to appropriate party – the report needs to be sent to the provider who ordered the test.
- Timely reporting of data – for most laboratory tests, an expected turn-around-time (TAT) is established and is often monitored as part of the quality assurance program.