Early and accurate diagnosis through biopsies can significantly improve treatment outcomes and the pet's overall prognosis. However, veterinarians must keep in mind the best practices and protocols for biopsies to avoid common mistakes and ensure safety when handling samples.

Factors Constituting a Successful Biopsy

Successful biopsies in veterinary medicine hinge on several key factors, such as:

• Accompanying information. A detailed submission form must accompany the sample. This should include the patient's signalment, relevant history, clinical signs, physical examination findings, radiographic or ultrasonographic summary, prior relevant laboratory results, therapies instituted, specific questions you would like answered, and clinical differential diagnoses. This context helps guide the pathologist's evaluation and interpretation, increasing the likelihood of an accurate diagnosis.
• Sample quality. The sample quality is crucial for accurate diagnosis. The tissue sample should represent the lesion or abnormality. The pathologist always wants more rather than less tissue, but we all understand this can be heavily impacted by the difficulty of safely obtaining the sample or other clinical factors.
• Handling and preservation. The collected sample must be properly handled to avoid contamination, physical damage, or degeneration. Tissue samples should be immediately preserved in formalin so maintain cellular integrity and allows for more accurate histopathological evaluation. 
• Proper labeling. Each sample must be clearly labeled with details, such as the patient's name, the anatomic site sampled, appropriate test code, and gross lesion descriptions, including the size, shape, color, consistency, symmetry, location, and border demarcation (i.e., well-demarcated versus invasive). Proper identification ensures the pathologist can evaluate the biopsy in the correct anatomical and clinical context.

7 Common Biopsy Collection Mistakes

Collection mistakes can compromise the sample quality, leading to diagnostic inaccuracies or delays. Here are some common errors and their solutions.

1. Inadequate Sample Size

A sample that's too small can limit the pathologist's ability to assess the tissue properly, especially if the sample does not include affected and healthy tissue.

Solution: Ensure the sample is large enough to represent the lesion or abnormality and includes a margin of healthy tissue. When in doubt, consult the lab about minimum size requirements before collection.

2. Incorrect Labeling

Mislabeling or failing to label the sample can cause confusion or mix-ups, particularly if multiple samples are taken from different locations.

Solution: Clearly label each sample with the patient's details and the specific anatomic location of the biopsy. If multiple sites are biopsied, use individual containers for each and accurately document their origin.

3. Poor Handling and Preservation

Mishandling, such as crushing or tearing the tissue during sample collection or transport, or preserving the sample improperly, can degrade the sample's quality.

Solution: Handle the sample gently and use the appropriate tools (e.g., forceps and scalpel) to avoid trauma. Immediately place the sample in 10% formalin at a 10:1 formalin-to-tissue ratio to ensure proper preservation.

4. Failing to Include Clinical Information

A sample with no detailed clinical information or history limits the pathologist's ability to interpret findings in the proper context.

Solution: Provide comprehensive clinical data on the submission form, including the patient's history, lesion description, duration, treatments, and the suspected diagnosis to guide the pathologist's evaluation.

5. Inappropriate Margin Expectations or Communication

In suspected neoplasia cases, communicate to the laboratory if you are aiming to remove a mass with wide margins for curative intent; anticipating minimal margins of healthy neighboring tissue; or are obtaining an incisional sample only with no applicable margins. If microscopically normal tissue margins are present, the pathologist provides the thickness measurement of the thinnest margin.

Solution: Consider your therapeutic goals and intent of the surgery.  If needed, discuss the case with an oncologist to understand the relevance of margins when you stage the disease. 

6. Inadequate Margins

In suspected neoplasia cases, a sample that does not include the tumor margins can hinder assessment of invasiveness.

Solution: Ensure the sample includes clear margins, especially for suspected tumors, to allow pathologists to evaluate the full extent of the lesion and its borders.

7. Delayed Sample Submission

Delaying sample submission can lead to tissue degradation, especially if the sample isn't preserved correctly.

Solution: Submit the sample to the lab as quickly as possible. If immediate submission is not feasible, ensure proper storage and preservation to maintain tissue integrity.

Practice Formalin Safety When Packaging Samples

Shipping formalin is regulated by the International Air Transport Association (IATA). Recommendations to meet IATA requirements and prevent processing delays include:

• Clearly label the formalin concentration on the jar. Concentrations of >10% buffered formalin cannot be shipped.
• The formalin-to-specimen ratio should be 10 parts 10% buffered formalin to one part tissue.
• The formalin should completely cover the specimen but not exceed 50% of the overall jar volume.
• Samples should be submitted only in adequately sized formalin-approved jars.
• Needles or sharps are prohibited in specimen submissions.
• When submitting a tiny specimen, place the sample in a microcassette first and then in the formalin jar.
• Do not submit specimens in glass tubes, which can break during transit.
• When submitting large specimens, consult the laboratory about their packaging protocols.

Veterinarians who focus on quality collection, proper handling, accurate labeling, and detailed accompanying information can increase the chances of obtaining a meaningful, accurate diagnosis, which is essential for developing an effective treatment plan.

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