Nonconformities in Veterinary Cytopathological Examinations: A Retrospective Study of Unsuitable Samples for Analysis

The aim of this study was to evaluate the main nonconformities that result in cytopathological samples inappropriate for diagnosis in veterinary medicine. All cytopathological samples, obtained from different canine and feline tissues/lesions, included in the study were received and classified as inconclusive by a single public laboratory of veterinary pathology, located in Pernambuco State, Brazil, between 2012 and 2016. Nonconformities regarding the smear quality, cellularity, presence or absence of hemorrhage, cellular overlapping, desiccation, and presence or absence of necrotic debris and/or artifacts were evaluated. Data were tabulated using Microsoft Excel 2007; absolute and relative frequencies were calculated using EPIINFO 3.5.2. From the 3268 cases received between 2012 and 2016, 190 cases were selected and comprised 514 inconclusive slides. The most frequent nonconformities detected were insufficient/absence of cellularity in 100% (514/514), inadequate submacroscopic presentation in 87% (446/514), and hemorrhage in 69% (356/514) of samples. Other features identified were cellular overlapping in 34% (175/514), inadequate staining in 31% (175/514), artifacts in 30% (154/514), desiccation in 28% (145/514), and necrotic debris in 26% (133/514) of samples. The implementation of laboratory standard operational procedures aimed at maintaining quality is essential. It is necessary to initially identify the main errors occurring in the processing stages as a way to guide and design strategies to avoid them.