Rehydration before wet fixation in conventional body fluid cytology – An 18‐year experience

• Published in: Cytopathology (Oxford) Vol. 29; no. 2; pp. 179 - 183
• Main Authors: Hsu, C.‐Y., Chen, T.‐C., Chang, C.‐B., Liu, Y.‐C., Lin, T.‐R.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.04.2018
• Subjects: Ascites; Ascites - pathology; body fluid cytology; Body Fluids; Cellular biology; conventional cytology; Cytology; cytopreparatory technique; Erythrocytes; Humans; normal saline; Pleural effusion; Pleural Effusion, Malignant - pathology; Preservation; Rehydration; rehydration method; Specimen Handling - methods; Staining and Labeling - methods; Tumors; conventional cytology; normal saline; cytopreparatory technique; body fluid cytology; rehydration method
• ISSN: 0956-5507; 1365-2303
• DOI: 10.1111/cyt.12524

Purpose In conventional cytology, preparation of a specimen by wet fixation for Papanicolaou stain is potentially subject to dry effect or cell loss which may make cytologic interpretation difficult or even impossible. We have been routinely making an additional smear for rehydration with normal saline (rehydration method) before wet fixation to overcome the above shortcomings. Methods We reviewed malignant pleural effusion and ascites 15 cases each in our cytology laboratory over the past 1 year. Four slides of each specimen were made. Two were air‐dried for Liu's stain (a Romanowsky stain) and the other two were wet‐fixed for Papanicolaou stain. The air‐dried smears were also served as retained cellularity control. One of the two wet‐fixed smears was processed as a control of preservation of nuclear detail whereas the other one stayed air‐dried for 10 minutes and then covered with normal saline (rehydration method) for 80 seconds before wet fixation. Results There was minor cell loss (P = .032). The cells appeared larger with good preservation of nuclear detail (P < .0001 by two‐sided Wilcoxon rank sum test) but no red blood cells retained on the slide after rehydration. Conclusion The rehydration method can effectively minimise cell loss, enlarge and preserve the cytological features of malignant cells with haemolysis. This method is simple, practical and good for cytological screening for tumour cells and interpretation especially in a bloody smear. We recommend that the rehydration method be part of traditional cytopreparatory work of wet fixation for Papanicolaou stain in conventional body fluid cytology. In conventional body fluid cytology, air‐dried smears covered with normal saline (rehydration method) before wet fixation is simple, practical and effective to minimize the cell loss, enlarge and preserve cytologic features of malignant cells with negligible extra load and cost during cytopreparation. We recommend rehydration method be part of, or even replace, traditional routine laboratory cytopreparation for wet fixation in conventional body fluid cytology.