Also referred to as a pap smear, a pap screening refers to a screening test that is more commonly used to detect cancerous as well as pre-cancerous cells in the female reproductive system. Quick and painless, this test was named after and invented by Georgios Papanikolaou, a Greek doctor in early cancer detection and cytopathology. Pap screenings are recommended to women aged 21 and above. They are also recommended yearly for any female of any age who is sexually active.