Evaluation of Histogel- and Gelfoam-embedded bronchoalveolar lavage and transtracheal wash fluids compared with cytocentrifuged and sediment smear preparations.

This research investigated the impact of different methods of preparing bronchoalveolar lavage fluid samples for analysis, finding that the traditional method of cytocentrifugation provides better results in terms of cellularity and morphology compared to the newer methods of Histogel and Gelfoam preparation.

Objective and Methodology

• The aim of this study was to examine whether bronchoalveolar lavage and transtracheal wash samples fixed with formalin after being embedded in Histogel or Gelfoam could provide comparable results to the traditional methods of preparing these samples which involve cytocentrifugation or sediment smear preparations.
• Eleven bronchoalveolar lavage and 3 transtracheal wash samples were available for the study. These included 8 from dogs, 1 from a cat, and 5 from horses. Part of these samples were prepared using the traditional cytocentrifugation and sediment smear methods for routine analysis, while the remainder was reserved for Histogel and Gelfoam preparations.
• The samples were evaluated by a single, board-certified pathologist who scored them for both cellularity (on a scale of 1-3) and morphology (on a scale of 1-4). The total nucleated cell counts (TNCCs) were also determined using a hemocytometer.

Results

• The analysis found that both cellularity and morphology were significantly worse in the samples that were prepared using sediment smear, Histogel, and Gelfoam methods compared to the cytocentrifuged preparations.
• Gelfoam preparations resulted in significantly worse cellularity scores than all other methods.
• The study also found a significant correlation between cellularity scores for sediment smears and Histogel preparations with TNCCs, indicating that these preparation methods could affect the number of cells detected in the samples.

Conclusions

• The traditional method of cytocentrifugation yielded the best results in terms of cellularity and morphology, and so is recommended for use whenever possible.
• The newer techniques of Histogel and Gelfoam preparation did not provide any advantages over sediment smear preparations, and in fact performed poorly when compared to cytocentrifuged preparations.
• Therefore, the researchers do not recommend the use of Histogel and Gelfoam methods for preparing bronchoalveolar lavage fluid samples for analysis.