Validation of a novel alcohol-free preservative solution in comparison with conventional prefixation on quality of serous body fluid smears

Background

We describe a novel alcohol-free preservative composed of glucose, mannitol, disodium hydrogen orthophosphate, thymol, and distilled water (glucose-mannitol–disodium dihydrogen orhtophosphate-thymol [GMDT] preservative) in appropriate proportion as an alternative to alcohol prefixation (APF) of body fluids.

Objectives

To assess the cytomorphologic preservation and staining quality of serous body fluid smears generated by GMDT preservative and compare it with smears processed by standard 50% APF.

Methodology

The study comprised 151 effusion samples. Each sample was equally divided into four tubes. Equal volumes of APF and GMDT preservatives were added to the first two tubes and left at room temperature for 24 h. Similarly, the corresponding preservatives were added to the third and fourth tubes and stored for 48 h. Two smears were prepared from the centrifuged sediments of each tube (all four tubes) and stained with May-Grünwald Giemsa and Papanicolaou (Pap) stains. Using a three-tiered scoring system, the smear examination was blinded to assess the extent of cellular preservation and the staining quality by two cytotechnologists and two cytopathologists. Statistical analysis was performed by STATA 16.0.

Results

Samples processed with the GMDT preservative at 24 h showed better cytoplasmic preservation and smear background, while nuclear features and staining quality showed no difference between the two preservatives. Mild cytoplasmic and nuclear degenerative changes were noted with the GMDT at 48 h, while all four parameters remained similar with APF at 24 and 48 h.

Conclusions

The newly developed alcohol-free, GMDT preservative, could be a feasible and cost-effective alternative to 50% APF, preferably when samples are processed within 24 h.