Susan J. Tornquist, DVM, PhD, DACVP

Lymph nodes are most often aspirated only if they're enlarged, but they may also be sampled to determine if there's metastasis of a tumor. Peripheral lymph nodes are one of the easier tissues to obtain a fine needle aspirate from as this can be done relatively painlessly.

Perform urinalysis within 30 minutes of collection or refrigerate. Allow urine to warm up to room temperature before analysis if it has been refrigerated.

The fluids most frequently sampled for cytology are peritoneal, pleural, synovial, cerebrospinal and pericardial fluids and washes of the respiratory tract. Some of these fluids are more easily obtained than others. All may potentially yield general, or sometimes more specific information about a disease process.

Inflammatory lesions may present as visible or palpable lumps, bumps, plaques, ulcers, accumulations of excessive fluid, or as abnormalities in organs that are visualized using imaging techniques. Cytologic examination of these types of lesions may be definitively diagnostic in many cases, or contribute to a diagnosis in other cases. When certain types of infectious agents are present, cytologic examination may be particularly rewarding.

A complete blood count (CBC) is a useful and very often-used method of screening and diagnosing patients who present for a wide variety of conditions. It may include both quantitative information about cell numbers, sizes, variability, etc. as well as descriptive information based on evaluation of a blood smear and description of any morphologic abnormalities or infectious agents present. A CBC is probably the most useful when both types of information are reviewed.

Cytology is a relatively easy, relatively non-invasive, fast and inexpensive diagnostic technique. Sometimes you actually get the diagnosis. Other times you don't get a specific diagnosis, but the cytologic findings can help you decide which diagnostic technique might be indicated as a next step. Also some potential diagnoses often can be ruled out.