Why didn’t I get the results I expected?
Tim Pasma
Animal Health Laboratory, University of Guelph, Guelph, ON.
AHL Newsletter 2024;28(1):4.
The process for obtaining laboratory test results can be divided into 3 phases: preanalytic, analytic and postanalytic.
The preanalytic phase includes activities occurring before the analysis of the test, such as preparation of the patient, history, physical exam and sample collection, handling and transport. This is the phase with the largest number of influences on the sample and its test result. Studies have shown that preanalytic errors make up the largest proportion of total errors with laboratory results. Proper handling of the sample in this stage is critical, as sample type and quality can adversely affect test results. Preanalytic errors can be avoided through the use of standardized procedures and training programs for clinic staff.
The analytic phase is the actual testing of the sample. The AHL has a comprehensive quality assurance (QA) program in place to prevent errors in the analytic phase. Quality control checks and tests are used to ensure instruments in the lab are providing accurate results. Other QA activities include annual proficiency testing programs for technicians performing accredited tests, participation in a quarterly proficiency testing service with other laboratories, and peer-review of anatomic and clinical pathology cases at weekly rounds sessions.
However, situations sometimes arise where diagnostic test results are inconclusive or unexpected based on the history and clinical presentation of an animal. In these cases, it is important to contact the laboratory as staff can help troubleshoot issues with the specimen or test interpretation. It may also indicate a problem with a test that warrants further investigation by the lab.
The postanalytic phase includes processes that occur after the sample is tested. Errors in this category include transcription errors, assigning results to the wrong patient medical record, using an incorrect reference interval, or incorrect assessment of results. Postanalytic errors can be avoided by using validation steps such as second-person verification to ensure that results are reported correctly. AHL
References
1. Camus MS. Quality control for the in-clinic veterinary laboratory and pre-analytic considerations for specialized diagnostic testing. Vet J 2016;215:3-9.
2. Frye E, Goodrich E. How to work with a veterinary diagnostic laboratory. Bovine Veterinarian; April 2023. https://www.bovinevetonline.com/news/veterinary-education/how-work-veterinary-diagnostic-laboratory
3. Walsh DJ. The non-pathologic, non-collection, and non-sample preanalytical small “stuff” that influences reliable laboratory results. Today’s Veterinary Technician 2016; September/October: 44-51.