Use of liquid-based preparations in urine cytology: An evaluation of Liqui-PREP and BD SurePath.

Dear Dr. Bedrossian: Conventional smears are tedious and time-consuming to screen due to nonuniform slide preparation and fixation. Features usually associated with conventional smears, such as, thick, overlapping cellular areas, obscuring inflammation, and blood and air-drying artifact result in poor cellular and nuclear preservation. Liquid-based preparations (LBP) are increasingly being used both for gynecologic and nongynecologic cytology including urine and fine-needle aspirations. Urine cytology comprises a large proportion of nongynecological specimens processed in most routine cytology laboratories. A recent paper reported on a larger series comparing conventional urine preparations with LBP. Liqui-PREP (LPR: LGM International, Fort Lauderdale, FL) and BD SurePath (BSP: BD Diagnostics, Franklin, NJ) are two commercially available LBP methods. In this study, the differences between LPR and BSP were evaluated for a variety of parameters including cellularity, cytomorphology, background features, etc. The material consists of 51 fresh voided urine samples from 25 patients with known urothelial carcinoma, which were obtained from January 2008 to June 2009 at the Mihara Medical Associations Hospital and the Shigei Medical Research Hospital. All patients provided informed consent. To equate cell density of LPR and BSP sample, urine samples were split equally. Each half of the urine samples was centrifuged at 3000 rpm for 5 minutes, and the supernatant fluid was discarded. Using a micropipette, 50 lL cell pellets were obtained and poured into a 15 mL centrifuge tube. Then, 1 mL of LPR preservation fluid and BSP CytoRich Red preservative fluid were added into centrifuge tube, respectively. After 30 minutes fixation time, LPR and BSP sample tubes were centrifuged at 3000 rpm for 10 minutes, and the supernatant fluid was discarded. As for the LPR sample, 0.2 mL of LPR Cellular Base Reagent was added in LPR sample tubes, and the cell pellet was resuspended using a vortex for 10 second. Following this step, 100 lL of the suspension were pipetted onto the slide to form a 2.0 cm diameter circle. Two LPR specimens were prepared for each case and were then dried and stained by the Papanicolaou method (Fig. C-1). As for the BSP sample, 0.2 mL of distilled water was added in BSP sample tubes, and the cell pellet was resuspended using a vortex for 10 second. After resuspension, 100 lL of the suspension was transferred into small plastic chambers, mounted on microscope slides, and fixed with 95% ethanol. Two BSP specimens were prepared for each case and were immediately stained by the Papanicolaou method (Fig. C-1). Four of the authors (Y. N., N. K., Y. S., and T. K.) microscopically analyzed all the preparations.