Specimen Preparation for Automated Cervical Cancer Prescreening

In order to obtain good specimens suitable for our automated prescreening machine for cervical cancer, Saccomanno's procedure being used for the detection of lung cancer was applied to the vaginal washings. The following procedure has been established: 10ml of vaginal saline washings is blended with a super high speed blender (Warning Timer-Light Blender, Scientific Products 8350 -1) at 21, 000 rpm for 5 sec. and fixed with an equal amount of 4% carbowax dissolved in 95%; ethyl alcohol for 30 min. and then centrifuged at 1, 500 rpm for 5 min. An appropriate amount of sediment is taken with a capillary pipet and homogeneously suspended in 4ml of 2% carbowax dissolved in 50% ethyl alcohol comparing the turbidity with that of Kingsbury-Clark's standard solution containing 10mg/dl protein so as to make the same turbidity. This solution is originally used for quantitative assay of urine protein. The suspension thus obtained is smeared with an automatic cytosedimentation machine (Sakura Autosmear, Model: CF-12SB) through 50μ square mesh filter at 1, 500 rpm for 5 min. The slides are allowed to dry completely. Subsequent Papanicolaou's stain is done by an automatic cytostainer (Sakura, Model: RSP-50). Following this procedure, 227 cases including 202 normal and 25 abnormal cases (dysplasia 8, carcinoma in situ 3, squamous carcinoma 13, adenocarcinoma 1) were examined and 126 good specimens (56%) were obtained. Good specimens were those which contained sufficient dispersed squamous cells for analysis without cellular clumps, excessive numbers of polymorphonuclear leukocytes or erythrocyte debris. Since the turbidity of suspensions was applied to the cell count, there were individual variations in the number of squamous cells. However, this procedure was simple enough for mass screening and excellent for cell dispersal. In addition, cells were sufficiently well preserved and showed no drying distortion as often observed in conventional Papanicolaou smears. In this study, Separate-L (Mixture of sodium metrizoate and ficoll) originally developed for separation of lymphocytes from blood was also applied to the vaginal washings of 26 cases to remove polymorphonuclear leukocytes which sometimes lead to misclassification of normal cells and was considered to be effective for 16 cases (62%). However, considering that this procedure is complicated and has a possibility for the concurrent loss of cancer cells, it requires further investigation.