Getting the most from your veterinary diagnostic testing

Jim Fairles

Animal Health Laboratory, University of Guelph, Guelph, ON.

AHL Newsletter 2022;26(3):3.

The goal of ensuring that all diagnostic test results are meaningful and accurate is the responsibility of the veterinary practitioner, and ultimately, everyone involved in the diagnostic test process.  Referral laboratories such as AHL have an extensive quality system in place to ensure that transmitted results are in accordance with quality standards.  Quality programs should be considered for in-house diagnostic testing as well.

These are three main steps of the diagnostic test procedure that require consideration to eliminate errors and to ensure valid results:

Preanalytic phase

The preanalytic phase occurs before a diagnostic test is run.  Sources of error during this phase include the following:

  • mislabeling or not labeling a specimen tube
  • allowing blood to clot before running a complete blood count
  • accidentally introducing EDTA into a blood sample for chemistry analysis (by inserting a needle into an anticoagulant tube and then into a serum tube)
  • improper preparation of samples for specialized testing

Analytic phase

The analytic phase is the actual sample analysis.  Errors during this phase are associated with the diagnostic equipment or personnel performing manual tests, and can be caused by the following:

  • expired reagents
  • deteriorating equipment
  • extrapolation of tests from one species to another
  • presence of precipitate or contaminants in stains
  • improper microscope maintenance
  • human error (for example, incorrect interpretation of blood smears or fecal samples)
  • failure to perform proper maintenance and quality control of in-house analyzers
  • improper storage of urine dipsticks (allowing exposure to moisture or light)
  • improper handling of urine dipsticks (dipping them vertically into a sample rather than keeping them horizontal)
  • failure to account for factors like cleaning solutions that can influence results

Postanalytic phase

The postanalytic phase occurs after sample testing is completed.  These errors involve data handling:

  • incorrect data entry (transcription errors - entering the wrong numbers)
  • assigning results to the wrong patient
  • loss of data

Avoiding errors

Some recommendations to minimize errors include the following:

  • use checklists to help avoid preventable errors
  • use written procedures
  • document personnel training
  • ensure correct sample volumes and processing times
  • document all errors
  • perform and document instrument maintenance
  • use properly stored, in-date reagents
  • repeat tests when results are not compatible with a patient’s clinical presentation
  • back up all data

Quality results are everyone’s responsibility!   AHL

References

1. Thompson BS. On the journey for great diagnostics – Tips and tricks to let the magic happen. AABP, St. Louis, Sept. 2019.

2. Quality Control in Veterinary Diagnostic testing https://www.dvm360.com/view/quality-control-in-veterinary-diagnostic-testing

3. ASVCP Quality Assurance and Laboratory Standards Guidelines https://www.asvcp.org/page/QALS_Guidelines

4. Getting the most out of your diagnostic laboratory submissions. Jim Fairles. AHL Newsletter 2020;24(1):2 https://www.uoguelph.ca/ahl/getting-most-out-your-diagnostic-laboratory-submissions

5. Specimen Reception update – more on getting the most from your diagnostic laboratory. Jim Fairles. AHL Newsletter 2021;25(3):2 https://www.uoguelph.ca/ahl/specimen-reception-update-%E2%80%93-more-getting-most-your-diagnostic-laboratory

6. AHL Accreditation and Quality Program https://www.uoguelph.ca/ahl/about-us/accreditation

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