Effects of the menstrual cycle on cytological false‐negatives in women with persistent cervical intraepithelial neoplasia

Objectives False‐negatives on cytology may be observed during follow‐ups for patients with persistent cervical intraepithelial neoplasia (CIN); however, the underlying reasons are unknown, and the relationship between the intra‐individual variability of false‐negatives and the menstrual cycle phase has not been elucidated. Therefore, this study aimed to determine whether the menstrual cycle influences cytological results to maximise the accuracy of such tests. Methods A total of 154 liquid‐based cytological (LBC) samples were obtained during follow‐ups for 26 patients with CIN, and the relationship between cytological results and the menstrual cycle, which was classified into six phases, was analysed. Results All LBC smears were satisfactory, and 20 of 154 (13.0%) specimens were negative for intraepithelial lesions or malignancy (NILM). A statistically significant association was observed between the cytological results and the phase of the menstrual cycle, χ2(2) = 19.322, P