Numerical analysis of cell populations in smear and monolayer preparations from the uterine cervix. I. The proportions of isolated, abnormal epithelial cells in slides from one applicator.

Automated screening systems with a receiver operating characteristic (R.O.C.) demand a minimum number of isolated and diagnostically relevant cells to classify cytologic specimens. Since routine Papanicolaou smears have not proven suitable for this, a new preparation procedure based on sedimentation velocity separation has been developed. A population analysis was made to assess the diagnostic relevance of the new procedure. For each of 21 histologically confirmed cases, three types of slides were made from material obtained by a single cotton-tipped applicator: (1) a routine smear and slides prepared from the (2) supernatant fraction and (3) sedimented fraction of the remaining material after suspension and separation. Results showed that only one-third of the squamous epithelial cells obtained in each case were found on the routine smear. Of those, only 39% were isolated cells, as compared with 81% of the cells in the residual (suspended) material. Further, in cases of slight and moderate dysplasia as well as carcinoma in situ, an enrichment of the number of pathologic cells was noted when comparing the sedimented fractions to the original suspensions. This would seem to prove the utility of the new preparation procedure as the basis for automated analysis based on samples instead of on single cells.