The Importance Of Validating Examination Results [continued]

from the May 2006 issue

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METHODS OF CORRELATION

Whenever possible, correlation of extracranial and intracranial cerebrovascular, peripheral arterial and visceral vascular exam findings should be made to angiographic findings produced by digital subtraction arteriography, contrast-enhanced computed tomography, or magnetic resonance angiography. As well, these exams should be correlated to surgical findings.

Because venous duplex has become widely accepted as the "gold standard" in the detection and diagnosis of venous thrombosis, the ICAVL Board of Directors realized that requiring correlation to venograms would prove difficult due to its very limited use in recent years. Consequently, additional methods of assessing examination and interpretation consistency, quality and effect on patient care were added to the Standards. The suggested methods of correlation for venous duplex include repeat duplex by a second sonographer at the same visit, overreading of exam results by a second physician, clinical outcome, and surgical findings.

Radiographic Comparison
When correlating the results of the noninvasive examination findings to the results of other diagnostic studies, the correlation must be reported using the categories present in the diagnostic criteria used in the laboratory.

Surgical Comparison
Patients who undergo surgical repair based upon noninvasive exam findings alone should be reviewed for discrepancies noted at the time of surgery and recorded in a log or worksheet. When applicable and available, the comparison should be made to location and extent of disease, as well as any surgical findings not noted in the noninvasive exam (i.e. additional stenosis, dissection, vessel anomaly). Any discrepancies should then be reviewed and discussed at the QA meeting.

DOCUMENTATION OF QUALITY ASSURANCE STATISTICS

Methods of tracking quality assurance vary and can be altered to best meet the needs of the laboratory; however, if not maintained routinely the task can become arduous. Some simple steps can be taken to assist in organizing the necessary data:

1. Keep an ongoing list of those patients with positive test results that might require further follow-up and/or intervention

2. Develop a log or data sheets that include dates, patient identification, noninvasive exam findings and correlation outcome. It is most effective to have separate data sheets or for each type of testing performed (table 1, table 2).

3. Develop methods to obtain follow-up information from providers such as radiologists, surgeons, and referring physicians.

4. Routinely enter data into the log sheets and correlate the comparison data, noting positive and negative outcome.

5. At intervals defined by the policy, findings can be entered into a QA matrix to calculate the overall accuracy.

UTILIZING THE QA DATA

After documenting the QA data, the results should be reviewed and discussed at the laboratory quality assurance meetings. Discrepancies in data, low accuracy and poor correlative results should be investigated and used to make the necessary adjustments in improving the technical and/or interpretive quality of the examinations and reports generated in the laboratory. In some cases, further evaluation can indicate that the negative correlation results are due to incongruity of the comparison exams or interpretations and can be further discussed with those practitioners.

ENHANCING THE LABORATORY'S QUALITY ASSURANCE PROGRAM
AND QUALITY CONTROL

DEVELOPING ALTERNATIVE METHODS OF QA

It is often expressed by laboratory personnel that there is increased difficulty in meeting the correlation requirements due to a decreased use of the historically typical "gold standard" comparison tests such as a digital subtraction angiography and venograms. If efforts to correlate exam findings to comparison exams are limited, the ICAVL Board of Directors will consider alternative methods of quality assurance.

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