There are formal processes that pathology laboratories undertake to ensure that the results of testing patient samples always give the same answers no matter which laboratory or how many times the sample is tested. There are two kinds of these processes: Internal Quality Control (IQC) which is how a laboratory ensures that they always get the same result on a sample and External Quality Assessment (EQA) which ensures that all laboratories testing the same sample will give the same result.
The term Quality Assurance comprises everything that the laboratory does to assure a high quality service to its users including IQC and EQA. Each day laboratories analyse IQC materials which are very similar to a patient sample with known concentrations of specific substances such as cholesterol and glucose to ensure that they are producing reliable results. If testing these samples does not produce the expected result then there is a problem with the testing process and no patient samples measured at the same time can be released until the problem is resolved.
EQA schemes are similar but a sample is sent to many different laboratories which all analyse this sample. All laboratories should obtain the same result on this same sample. If they do not then there is a need to investigate the testing process. This ensures that it doesn’t matter where a patient sample is analysed it will always have the same result as if it was tested in any other laboratory. EQA schemes are managed by independent non-commercial organisations and provide objective data on individual laboratory and test method performance and can help laboratories identify problems by comparing their performance with others using the same or different testing methods.
Laboratories have comprehensive quality assurance programmes to ensure that every step of the process of producing results – requesting, sampling, analysing and reporting – is monitored to ensure the correct tests are performed, that reliable results are produced, and that these are communicated to the appropriate doctor in a timely manner.
While not infallible, each laboratory’s QA programme rigorously defines requirements for staff competence, equipment maintenance and monitoring, and other standards of operations. In addition to following their own in-house guidelines, laboratories are monitored by professional accrediting organisations [See Laboratory accreditation - the basis for confidence].