a simple, painless test used most commonly to detect cancer of the uterus and cervix; it is based on the discovery by Dr. George N. Papanicolaou (1883–1962) that malignant uterine tumors slough off cancerous cells into surrounding vaginal fluid. Called also
Pap test and
Pap smear.
The Papanicolaou technique, an exfoliative cytological staining procedure, is used also in diagnosis of lung, stomach, and bladder cancers. It can be performed on any body excretion (urine, feces), secretion (sputum, prostatic fluid, vaginal fluid), or tissue scraping (as from the uterus, cervix, or stomach). The sample is removed from the area being examined, placed on a glass slide, stained, and then studied under a microscope for evidence of abnormal or cancerous cells.
In five minutes the Pap test can reveal uterine or cervical cancer at a stage in which it produces no visible symptoms, has done no damage, and usually can be completely cured. It is recommended that all women over age 18, and younger women who have been sexually active, should have an annual Pap test and pelvic examination.

Pap smear. From Lammon et al., 1995.