Management of Epithelial Cell Contamination in Wet Prep Specimens

Understanding the Significance of Epithelial Cells

The presence of squamous epithelial cells on wet preparation suggests that the specimen is contaminated with upper airway secretions, which compromises the diagnostic accuracy of the sample, according to the American Thoracic Society 1, 2
Large numbers of bronchial epithelial cells indicate that the sample may not have adequately collected material from the distal airspaces, which is critical for accurate diagnosis, as stated by the American College of Chest Physicians 2
An adequate specimen should contain minimal epithelial cells to ensure proper evaluation of other cellular components, as recommended by the Infectious Diseases Society of America 3, 2

A specimen is considered inadequate or unsatisfactory when it contains more than 1% epithelial cells or more than 10 epithelial cells per low-power field (100x magnification), according to the Clinical and Laboratory Standards Institute 3
Specimens reported as unsatisfactory for evaluation should be obtained again to ensure accurate diagnosis, as advised by the Infectious Diseases Society of America 4
The presence of large numbers of epithelial cells interferes with the interpretation of other cellular components such as white blood cells, bacteria, and other microorganisms, as noted by the American Gastroenterological Association 2, 5

When numerous epithelial cells are identified, the specimen should be recollected to obtain an adequate sample, as recommended by the Infectious Diseases Society of America 4, 3
Ensure proper sampling technique to minimize contamination with epithelial cells, as suggested by the American Thoracic Society 2
For vaginal specimens, proper collection technique involves avoiding contact with the vaginal walls when targeting cervical sampling, as advised by the Centers for Disease Control and Prevention 4

Process the specimen within 1 hour if in nutrient-poor media (e.g., saline) or within 2-3 hours if in nutrient-supplemented media, as recommended by the American College of Chest Physicians 2
Use appropriate staining techniques (Wright-Giemsa, May-Grunwald-Giemsa, or Papanicolaou) to enhance visualization of cellular components, as suggested by the College of American Pathologists 2, 6

Assess the new specimen for adequacy before proceeding with diagnostic interpretation, as advised by the Infectious Diseases Society of America 4, 2
Perform differential cell counts on adequate specimens, noting the presence and relative numbers of white blood cells, bacteria, and other microorganisms, as recommended by the American Thoracic Society 2

Do not interpret results from specimens with excessive epithelial cells, as this leads to inaccurate diagnosis, as warned by the Clinical and Laboratory Standards Institute 3, 2