Invasive Cytology of Internal Organs

Fine needle aspiration (FNA) cytology is an excellent adjunctive tool in small animal practice. It is often diagnostic, requires little specialized equipment, and can rapidly provide useful information. Superficial lumps and bumps are readily aspirated due to their accessibility. Familiarity with routine sample acquisition and examination is a prerequisite of using FNA cytology for more complex applications. Aspiration of internal body cavities, organs, and masses can be considered an invasive procedure because the area of interest is enclosed within the "black box" of the animal enhancing the risk of complications. Isolating the lesion, obtaining a quality sample, and monitoring the site for complications is more difficult. Despite the invasive nature of obtaining FNA cytologic specimens from thoracic and abdominal sites, the surgical alternative as a diagnostic tool often can be avoided by appropriate application of FNA cytology. As is true for any diagnostic test, understanding the limitations of FNA cytology is equally as important.