Conventional versus Liquid-based Cytology: “Man versus Machine”

BACKGROUND: Liquid-based cytology (LBC) can improve adequacy, monolayer quality with a clean background compared to conventional smears (CS). AIMS AND OBJECTIVES: The objective was to compare the quality and diagnostic yield of CS and LBC in routine cytological investigations. MATERIALS AND METHODS: This retrospective study consisted of 306 samples (255 gynecological, 39 nongynecological, and 12 fine needle aspiration cytology [FNAC]) during a 2-year period (2019–2020). From each patient, two samples were collected in the same manner in the same sitting and processed by CS and LBC (ThinPrep® 2000, Hologic Inc.). Both CS and LBC were compared for adequacy, quality, representativeness, inflammation, hemorrhage, necrosis, preservation, reactive changes, organisms, atypia/dysplasia/malignancy, and preparation/screening time. Statistical analysis was performed. RESULTS: No statistically significant difference was noted for adequacy, representativeness, reactive changes, preservation, and atypia/dysplasia/malignancy. CS was better in cellularity and diagnosis of inflammation and organisms, whereas LBC had a clean background and the difference was statistically significant (P = 0.0005). CONCLUSIONS: CS was equivalent to LBC in adequacy, representativeness, reactive changes, and atypia/dysplasia/malignancy. Adequacy comparable to LBC can be achieved in CS by careful sample collection, processing, and screening by trained cytotechnologists. CS was better in detecting organisms and inflammation than LBC. The advantages of LBC were monolayer smear, clean background, and lesser screening time, but the demerit was higher cost and longer processing time. Therefore, LBC is best suited to those laboratories having high sample inadequacy rates, lack of competent cytotechnologists, and no financial constraints. Either man or machine, appropriate and adequate sample collection by trained personnel forms the cornerstone for ensuring adequacy in both CS and LBC.