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Types of Pap Smears

Nov 9, 2010 | By Janna Smith
Types of Pap Smears
Photo Credit Microscope image by e-pyton from Fotolia.com

The death rate from cervical cancer has fallen nearly 70 percent since Pap smears were first used to detect early cervical cancer, according to the American Cancer Society. The test is a simple, painless way to look for precancerous and cancerous changes in the cells of the cervix. Technology developed in the 1990s has made the Pap smear an even more sensitive test for identifying abnormal cervical cells.

Cervical Cancer

Cervical cancer is a cancer of the cervix, or the lower part of the uterus. It is caused by the Human Papillomavirus, or HPV, a virus which is present in the majority of sexually active women. Certain types of the virus can cause changes in the cells of the cervix and may later lead to the development of cancer. Precancerous conditions and early cervical cancer have no symptoms, so screening for the disease is essential in identifying it before it becomes more severe. The Pap smear is the screening test used to look for these changes.

Features

The Pap smear is named after Dr. George Papanicolaou, a physician who first developed the test in the 1930s. The Pap test involves taking a scraping of cells from the cervix, placing the cells on a slide, and then examining them under the microscope for changes that may indicate cancer or precancerous conditions.

The cells for the Pap smear are collected in a doctor's office by a health care professional, who uses a tool called a speculum to open the vagina and better visualize the cervix. The professional then uses a spatula to scrape the outer edge of the cervix, and a brush to scrape the inside of the cervix. The spatula and brush collect cells from the cervix to be examined under a microscope. After the cells are collected from the cervix, they can be processed in two main ways.

Types

Liquid-based Pap smears, such as the ThinPrep and SurePath Pap smears, are prepared by placing the scrapings from the spatula and brush into a special type of solution which preserves the cells. The cells in the liquid are processed, and the liquid is placed onto a glass slide so that it can be examined under a microscope.

Conventional Pap smears are prepared by rubbing the scrapings from the spatula and brush directly onto a glass slide.

In both liquid-based and conventional Pap smears, the cells on the glass slide are stained with dye so that they can be seen under the microscope. A laboratory professional or pathologist then examines the slide under the microscope.

For liquid-based Pap smears, the glass slides may also be examined by a computer system to check for abnormal cells. The imaging system searches for and marks abnormal cells, which are then reviewed by a doctor or laboratory technologist.

Considerations

Both conventional and liquid-based Pap smears are extremely sensitive ways to find atypical cervical cells. Liquid-based Pap smears have a few advantages: the cells from liquid-based Pap smears can be used to test for the virus that causes cervical cancer, HPV, as well as other types of infections. An additional advantage is that the cells in liquid-based Pap smears are more easily seen under the microscope, and are not as easily obscured by blood or mucus on the glass slides.

A 2007 study in the "British Medical Journal" found that imaging systems, in association with liquid-based cytology, have been found to pick up a few more cases of precancerous cells than other types of Pap smears.

Expert Insight

The American Cancer Society recommends that women be screened for cervical cancer within 3 years of first having sex.The recommendations about the frequency of the exam vary for women of different ages and circumstances; based on medical history and test results, a health care professional can ensure that the Pap smear is performed as recommended.

References

Article reviewed by Roman Tsivkin Last updated on: Nov 9, 2010

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