Clinical Pathology FAQs 2017-09-20T15:52:10+00:00

Frequently Asked Questions

What is veterinary clinical pathology?

Veterinary clinical pathology is a medical specialty concerned with the diagnosis of disease based on the laboratory analysis of bodily fluids, such as blood, urine, and tissue samples using the tools of chemistry, microbiology, hematology, and molecular pathology. A veterinary clinical pathologist must complete veterinary school as well as three years of specialty residency training.

What is cytology (aka cytopathology)?

Cytopathology is a diagnostic technique that examines cells from various body sites to determine the cause or nature of the disease. A cytopathologist examines cells that have been exfoliated (shed), scraped from the body, or aspirated with a syringe needle. Cell specimens are processed as necessary and examined microscopically for the diagnosis of cancer, precancerous conditions, benign tumors, inflammation, and some infectious agents. The test results are communicated to the primary veterinarian for surgical or medical follow-up with the patient as necessary.

What services are offered by PEC’s clinical pathology service?

Test Description Sample Requirements Special Notes
Cytology Description, interpretation, comments, and representative image(s) Air-dried, unstained slides or previously stained slides

(FNAs, impression smears, swabs)

$5.00 – ALP staining in cases of suspected osteosarcomas
Fluid Analysis

(Cavity, BAL, TTW)

TNCC, protein concentration, PCV, cytologic evaluation EDTA fluid sample
Synovial Fluid Analysis TNCC, protein concentration, mucin clot test, cytologic evaluation EDTA and RTT synovial fluid samples* *RTT necessary for mucin clot test only
CSF Analysis TNCC, cytologic evaluation

(no protein concentration)

EDTA CSF sample** ** Call for instructions if sample will not be analyzed within 4 hours
Urinalysis or Urinary Sediment Cytologic evaluation RTT urine sample
Buffy Coat Review Hematologic evaluation of buffy coat prep slides EDTA whole blood
Bone Marrow Cytology Hematologic evaluation Air-dried slides +/- EDTA blood*** ***CBC performed within 24 hours recommended for the most accurate interpretation
Blood Smear Review Hematologic evaluation Unstained or previously stained blood smears
CBC with Path Review In-house automated CBC with manual diff and smear review EDTA whole blood +/- blood smears
STAT charge Add’l charge for immediate review of a sample upon receipt

How much do the various services cost?

Veterinarians are welcome to contact us directly (509-326-7289 or clinpathpec@gmail.com) for a full list of test fees.

What sample(s) should be submitted?

Please see services table above for sample details.

How can samples be submitted?

A courier is available upon request to pick up samples Monday through Friday. As soon as the sample is ready for submission, please call PEC at (509) 326-7289 so the courier can plan to visit your practice. Alternatively, samples can be delivered to PEC’s front desk or mailed to PEC (21 E. Mission Ave, Spokane, WA 99202).

How and when should my veterinarian receive results?

Samples picked up by PEC’s courier or dropped off before 3 pm will be reported on the same business day. Samples submitted after 3 pm may be reported the following business day, depending on the pathologist’s caseload. For an additional charge a STAT evaluation may be requested.  A STAT sample will be read immediately upon arrival, the referring veterinarian called with a verbal interpretation, and a report faxed promptly.  Diagnostic reports will be emailed and/or faxed to the referring veterinarian. Reports include colored images so email is preferred.

Can veterinarians call to consult on tests performed elsewhere?

Clinicians are welcome to call (509-326-7289) if they’d like to discuss the interpretation of prior testing or seek recommendations for further tests. Clients who call with questions regarding tests or testing will be directed to consult with their primary veterinarian.

What is the best way to collect samples for cytology?

The best cytology samples are those that have high numbers of intact, dispersed nucleated cells and very little blood contamination. The technique used (e.g., aspiration, swabbing) has a significant impact on how many cells are collected, how many of those cells are ruptured, and how much blood is inadvertently introduced.

Secondarily, the method used to transfer those cells collected to slides impacts the percentage of ruptured cells and whether they are evenly dispersed for ideal staining and review. Consequently, care should be taken with both steps.

For cutaneous masses, internal organs, lymph nodes, or any other lesion that can be collected by fine needle biopsy, the gentlest method to collect cells is the “tattoo method.”

Tattoo Method

This method of needle biopsy does not use any aspiration (negative pressure) thus it decreases the risk of cell rupture and sample hemodilution. Without the negative pressure generated by aspiration, however, few cells would be collected from more firm or fibrous lesions or connective tissue tumors (e.g., sarcoma).

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For the “tattoo method” of fine needle biopsy the needle can either be introduced into the lesion without a syringe attached, or the needle can have a syringe attached that contains 1-2 ml of air in the barrel. The addition of the syringe may make the needle easier to hold and manipulate.

Aspiration Technique
The “aspiration” technique of fine needle biopsy involves the generation of negative pressure while the needle is embedded in the lesion to help pull cells into the bore of the needle. Typically, a small needle (e.g., 22 ga. or 25 ga.) is preferred, with smaller needles causing less sample hemodilution and less discomfort for the patient.

The size of the syringe will dictate how much negative pressure can be generated during aspiration. A 3 cc syringe is typically adequate, but if a very fibrous lesion is being sampled a larger syringe (e.g., 6 or 12 cc) could be considered to help collected sufficient numbers of cells for review.

 

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Make sure to only aspirate when the needle is in the tissue of interest. If negative pressure is maintained while the needle is removed, inadvertent sampling of the superficial tissues will occur and complicate cytologic interpretation.

Swab Cytology
For swabs (e.g., ears, vaginal canals, draining tracts), moisten the swab if the lesion is dry to prevent cell rupture. If the lesion is already moist (e.g., draining tract) then this step is unnecessary. Impression smears from biopsy samples or cutaneous lesions tend to generate good cytology samples, but if the lesion/tissue is bloody or exudative then it should be gently cleaned prior to making the impressions. This will prevent collection of only secondary processes (e.g., hemorrhage, secondary inflammation and infection).

Cytology Slide Preparation

Once the sample has been collected, the cells need to be transferred to clean glass slides in such a way that they are evenly dispersed and intact. If the sample is watery (e.g., lymph node aspirate, cystic fluid, cavity effusion) slides can be prepared using the wedge technique. This method is typically employed to make blood smears, but it is a very gentle method to prepare cytology slides that will cause minimal cell rupture.

 

cytologyslidepreparation

When using the wedge technique, the angle of the top slide will dictate the length of the smear. A steeper angle (less acute) will make a shorter smear and is good for samples that are waterier or blood that is anemic. Lowering the top slide (more acute angle) will make a longer smear which is good for thicker samples or blood with a higher packed cell volume due to hemoconcentration.

For thicker samples or samples with “chunks” the squash prep method can be employed. This is a very versatile technique and successful provided it is performed properly. Once the sample is expelled on a slide, another clean and dry slide is gently placed perpendicularly on top to “squash” or spread the sample. The weight of this top slide is more than sufficient to spread the sample and any additional downward pressure will likely cause cell rupture. The two slides are then gently separated, generating two slides for review.

buffycoat

If the slides are placed parallel to one another an excess of surface tension will be generated between the glass and the sample. As a consequence, resistance to separating the slides will be felt and the resulting separation of the slides will cause cell rupture.

Questions?

The success of cytology as a diagnostic is a team effort, relying heavily on proper sample collection and slide preparation. As such, we are more than happy to answer specific questions about sampling and slide preparation (509-326-7289).