CLINICAL LAB SCIENEC

CHAPTER 10: QUALITY ASSURANCE 247
Analyzing Quality Control Results
The list of rules described previously indicate how to determine if patient results
can be safely reported or if a problem exists. This section is a more in-depth
discussion of the rules and the corrective action to take when Westgard rules are
violated.
Most QC rules will detect both random and systematic error, but a preanalytical
error might not be uncovered unless a repeat specimen is drawn. Remember,
there are preanalytical factors, analytic, and postanalytical issues that may
adversely affect the results that are reported. It would be well to remember factors
involved with all three aspects of testing to be more effective as a professional.
Only a few control rules have adequate sensitivity for the detection of both
random and systematic errors. Effective QC procedures require sensitivity to
both types of error and should have an acceptable false rejection rate, which
should be a low value. Improved sensitivity to both random and systematic error
may be accomplished by combining QC rules. QC procedures using a combination
of rules are called “multirule control procedures” or are multirule procedures
such as the ones developed by Westgard. Multirule procedures combine
both the rules and the order in which the rules are applied to the control data.
According to CLIA 88 requirements, if control results fall outside an established
range of acceptable values, the technician or technologist must take action to
rectify the problem. It is also mandatory that any action taken to correct the
problem be documented. It is easier to correct a systematic problem or a random
error immediately following the discovery of the problem.
Remember that control results must fall within acceptable limits before any
patient results may be reported. Sometimes physicians will demand results even
before remedial action has been taken and the results repeated and verified, but
officially no results may be disseminated until QC results are acceptable. It is
important to repeat the original patient test results if it is determined by the
remedial action that the patient test results could be affected. Guidelines that are
readily available for the laboratory’s technical workers should be in place defining
the corrective action that should be taken as found in the following list.
Steps to Follow When Control Results Are Out of Range
It is essential to arrive at a point as quickly as possible where patient results can
be released. The following steps start with the simplest remedy first and progress
to more time-consuming procedures that tend to further delay the dissemination
of laboratory results that may affect a patient’s treatment. The steps should be
done in the order provided.
Remember, if the first step corrects the problem, no further action is required.
Fortunately, the first two steps will eliminate the errors in most cases. Controls
and sometimes standards must be reconstituted and allowed to stand for up to
30 minutes before they are ready for use. This delays the test results for quite a
period of time, so if step 1 corrects the problem, much time can be saved, thus
the reason for following the correct order for action.
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