Masking effect of hormonal contraceptives on discriminating quantitative features of visually normal intermediate cells in positive and negative cervical smears.

In quantitative studies of visually normal intermediate cells in smears from patients with cervical neoplasia, the contraceptive status of the patients has not previously been taken into account. In this study cervical smears from 151 patients with cervical intraepithelial neoplasia (CIN) III or invasive carcinoma and from 360 normal controls were grouped according to week of menstrual or pill cycle and mode of hormonal contraception. The nuclear-cytoplasmic (N/C) ratio of visually normal intermediate cells in smears from patients with neoplasia was significantly different from that of the normal controls (P less than .001). Based on nuclear area and N/C ratio, the percentages of intermediate cells correctly classified as having come from positive or negative smears were significantly better in women with ovulatory cycles (non-users) than in women using hormonal contraceptives (P less than .025). It is concluded that hormonal contraceptives can mask the salient quantitative features of visually normal intermediate cells from patients with CIN and the contraceptive status thus has to be taken into account in such studies.