Effect of cytological fixative and environmental conditions on nuclear morphometric characteristics of squamous epithelial cells in sputum

Abstract

Sputum samples for lung cancer screening trials are typically collected at home into specimen containers prefilled with cytologic fixative. Collection, transit, and storage expose samples to environmental conditions that may introduce artifacts that could confound evaluation. We examined whether the type of cytological fixative and exposure to different environmental conditions introduces artifacts that affect cytological analysis. Sputum fixed in Saccomanno fluid (SAC), containing methyl, ethyl, and propyl alcohols and polyethylene glycol, or CytoRich Red solution (CRR), containing methyl and isopropyl alcohols and ethylene glycol, plus formaldehyde, was aliquoted and exposed for 8 h to the following conditions: (a) -20 degrees C freezer, (b) 60 degrees C oven, (3) direct sunlight, and (4) room temperature. Cell morphometry was evaluated using computer-assisted image analysis (CAIA). The values obtained for CAIA analysis of sputum were affected by the type of fixative used. Temperature extremes and sunlight dramatically altered nuclear morphometry of SAC-fixed cells. Artifacts were not observed in CRR-fixed cells. The effects of environmental exposures were minimized if sputum was placed in a formalin-containing fixative such as CRR. If an alcohol-based fixative such as SAC is used, sample handling, transport, and storage must be monitored to prevent the introduction of artifacts.