He first published a large series of cases in Diagnosis of uterine cancer by the vaginal smear (Papanicolaou & Traut, 1943). The sampling technique has hardly changed ever since.
The test is simple and effective, consisting of simple cervical swab to collect a sampling of cells. These cells are placed on a glass slide and checked for abnormalities in the laboratory. Approximately five to seven percent of pap smears produce abnormal results, such as dysplasia, a possibly pre-cancerous condition. Many of these abnormalities are NOT due to cervical cancer, but they are an indicator that increased vigilance is needed.
It is recommended that all sexually active women have an annual pap smear and examination to detect any cancer in its early stages. If a smear returns abnormal results, the test will need to be repeated in three or six months instead of a year. Three abnormal results in a row is an indicator of the need for further surgical intervention.