In-house diagnostic pathology and pathology referrals
Ratification Date: 15 Feb 2013
Veterinarians offering ‘in-house’ diagnostic pathology services should ensure that equipment and services are subject to regular quality control and quality assurance testing. Staff should be thoroughly trained in the correct use and routine maintenance of diagnostic equipment. When interpreting the results, staff should be aware of the limitations and interferences that may affect the test results.
Many veterinary practices use in-house clinical pathology, haematology and cytology equipment to offer a range of diagnostic and treatment monitoring services to clients.
When veterinarians are choosing pathology services or instrumentation, they need to be aware of the concepts of quality control (QC) and quality assurance (QA).
- The judgment of the attending veterinarian about the need for pathology testing and the particular pathology tests used in an investigation or work-up will vary with each clinical situation or circumstance.
- Validated test results should be used to make judgments on the disease status and prognosis of patients at all times.
- Results may be inaccurate or invalid if:
- the instruments used have not been validated for samples for the common animal species tested
- incorrect sample types or inappropriately stored and handled samples are tested.
- Precise, thorough and uniform training of staff on the correct use of diagnostic equipment is essential and must include maintenance, troubleshooting, QC and correct sample collection and handling. Ongoing competency to perform testing must also be assured.
- Qualified personnel must regularly maintain the equipment used.
Features of particular areas of diagnostic pathology
All practices using in-house biochemistry equipment should undertake regular QC testing, at intervals appropriate to the equipment being used. The QC test material should be appropriate, have reference values pertinent to the equipment being used and the species being tested, and cover the range of results likely to be encountered. QC data should be checked against the expected range and the results acted upon before any diagnostic samples are tested.
Reagents and QC material should be stored under appropriate conditions. Expired reagents must never be used for diagnostic purposes.
In-house haematology and biochemistry equipment should have QC run on a daily basis.
Blood films should be made, stained and examined by a veterinarian on all primary diagnostic cases.
Cytology and other microscopic examinations
The practitioner must be aware of the potential value and accuracy of techniques involving microscopic examination (fine needle aspirates, impression smears, tape preparations and skin scrapings). This includes the pitfalls and shortcomings associated with sample preparation and examination. Cytology staining solutions should be regularly replaced.
If possible, participation in an external QC programme is recommended and the results acted upon.
The incubation process, storage procedures, inoculation procedures and materials must be appropriate and valid.
Negative and positive controls should be run with all diagnostic serology testing.
The diagnostic requirement for a complete or partial urine analysis needs to be considered in each clinical situation.
A necropsy should be offered to a client if the information gained could aid in the diagnosis or treatment of a wider disease situation, or in the event of an unexpected or untimely death of an animal. A necropsy may also be appropriate where the client or veterinarian requires a definitive diagnosis as to the cause of death.
The owner should be given the option of deciding who will perform the necropsy: the attending veterinarian, a veterinary colleague or an independent veterinary pathology laboratory. Necropsy must not be performed without the owner’s consent.
Clients should be offered a complete necropsy to ensure that maximum diagnostic information can be gathered. Appropriate diagnostic specimens should be taken from all necropsies and stored for future reference.
There are three possible avenues for referral of veterinary clinical pathology and diagnostic tests:
- commercial, university and government veterinary pathology laboratories
- medical pathology laboratories, preferably with veterinary accreditation, or
- neighbouring practices with appropriate equipment.
All commercial and government veterinary pathology laboratories that perform referral testing should be accredited to ISO/IEC 17025: General requirements for the competence of testing and calibration laboratories. Accreditation provides independent assessment of technical competence to perform a range of testing activities. [Refer to NATA (nata.com.au) for a complete listing of accredited veterinary facilities.] If the practitioner has a choice of commercial pathology laboratories, an accredited laboratory should be used in preference to an unaccredited laboratory.
Referring veterinarians need to be aware that medical pathology laboratories may not be adequately set up for handling veterinary testing samples or have the appropriate expertise to understand the limitations and interpret the results obtained.
Practitioners who refer clinical pathology to neighbouring practices must be aware of and accept the QA and QC of the testing performed by that practice.
Practitioners who accept referral of clinical pathology from a neighbouring practice must accept responsibility for the results generated by their equipment.
Pathology samples for referral must be collected, stored and handled correctly to optimise the value of the test results. Samples must be packaged and transported to the referral laboratory in accordance with any current legislative or industry requirements.