Pap smear

Pap smear, medical screening procedure used to detect precancerous and cancerous changes in the cells of the cervix. Developed in the 1940s by physician George Papanicolaou, the test involves collecting cells from the cervical surface during a pelvic examination and then investigating them microscopically for abnormalities.

A Pap smear typically entails the collection of two specimens for laboratory staining and examination, one consisting of vaginal secretions from the ectocervix and the other of scrapings from the surface of the endocervical canal, where cancerous growth frequently originates. In practice, these cells may be collected together in one sample, such as when using a broom-type device for liquid-based cytology, or they may be collected separately, such as with a spatula for the ectocervix and a brush for the endocervical canal, and then combined in a single specimen vial or slide. The Pap smear may reveal malignant cells not only from the cervix but also from the endometrium (the mucous coat of the uterus) and the ovaries.

The development of other cervical cancer screening methods, particularly human papillomavirus (HPV) testing and liquid-based cytology, has reshaped the role of the Pap smear in clinical practice. HPV testing, which directly detects the virus responsible for most cervical cancers, is more sensitive than cytology alone and in many regions of the world has been adopted as a primary screening tool or in combination with Pap smears (co-testing). Liquid-based cytology, introduced in the 1990s, improved sample quality and allowed concurrent HPV testing from the same specimen, increasing diagnostic efficiency. As a result, Pap smears are now performed less frequently, often at longer intervals (every 3–5 years rather than annually or biennially), and in some regions they are being replaced altogether by HPV-based screening. Despite these changes, the Pap smear remains an important tool worldwide, particularly in low-resource settings where HPV testing may be less accessible, and continues to be credited with dramatically reducing cervical cancer incidence and mortality since its introduction.