Cervical and vaginal cytology, Papanicolaou test (PAP), is the most effective test for screening of preneoplastic lesions, and cervical cancer prevention. Its sensitivity goes from 50 to 98%, according to different statistics, and this variation is related to the sampling procedure. A satisfactory smear should be taken from the transformation zone, the junction between endocervix and exocervix. According to Bethesda, metaplastic and/or endocervical cells should be observed under the microscope. The traditional PAP smear includes an exo-endocervical sampling using the Ayre spatula; however, only near 50% of the smears are representative of the transformation zone. In this case report, we present the case of a 40-year-old woman who had negative cytology in five consecutive annual PAP smears, none of which showed metaplastic or endocervical cells. A new sample evidenced a carcinoma in situ (HSIL: high-grade squamous intraepithelial lesion). We emphasize the importance of performing a correct exo-endocervical sampling to allow prompt detection of all premalignant lesions and to prevent cervical cancer, which still persists with high mortality worldwide.
Keywords: Papanicolaou test; endocervix; uterine cervical neoplasm.