The Papanicolaou test is a method of cervical screening used to detect potentially precancerous and cancerous processes in the cervix or, more rarely, anus or the vaginal vault. In patients who have had a hysterectomy, the cervix is normally removed and Pap smears are not indicated. Abnormal findings are often followed up by more sensitive diagnostic procedures and, if warranted, interventions that aim to prevent progression to cervical cancer. The test was independently invented in the 1920s by the Greek physician Georgios Papanikolaou and named after him. A simplified version of the test was introduced by the Canadian obstetrician Anna Marion Hilliard in 1957.