What is it?
The surface of the cervix comprises several layers of squamous cells. As these cells grow and develop, they move from the bottom inside layer to the top outside layer where they can be sampled easily. The Papanicolaou (PAP) smear is the standard screening test for examining these cells and the glandular cells that line the endocervical canal (opening in the cervix that connects the uterus to the vagina) for a precancerous condition. An abnormal finding on either test suggests the presence of a cellular abnormality, but there are many (5 to 20 percent) false-positive tests (abnormal test but no disease). Therefore, the results are used to guide subsequent evaluation and possible therapy.