A cervical cytological sample is considered satisfactory for cytological diagnosis when their composition reflects the mucosal lining of the cervix, encompassing ectocervical, squamous metaplastic cells and endocervical columnar cells in fair numbers. It is generally agreed that majority of epithelial abnormalities that eventually lead to an invasive cancer originate in the squamo-columnar junction (transformation zone). As stated by the British Society for Clinical Cytology (BSCC), a cervical smear if properly taken should contain cells from the whole transformation zone(TZ). The sample should contain a sufficient quantity of epithelial cells, and both metaplastic and columnar cells should be present. According to the Bethesda System, an adequate smear contains.
