Imaging system assists Pap smear screening

Published March 8, 2005 2:20 am
This is an archived article that was published on sltrib.com in 2005, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

Most women dread having Pap smears - they can be painful, embarrassing and overall unpleasant. But they can also save lives, and the good news is the technology behind this diagnostic test is becoming more advanced.

Technicians at LDS Hospital are using an imaging system that especially improves cervical cancer detection - the first hospital in the Intermountain West to have the computerized screening. Pap smears are the most effective way to detect cervical cancer.

Called the ThinPrep Imaging System, it is the first fully integrated, interactive computer system that assists technologists and pathologists in the screening of Pap smear slides.

"With traditional Pap smear tests, cells are taken from the cervix and smeared onto a glass slide for examination. However, there is room for error with this method because the cells can dry or are covered by blood and mucous, obscuring any abnormal cells," said Brent Brewerton, director of Intermountain Health Care's Cytology Program at LDS Hospital.

About 15,000 women in the United States get cervical cancer every year, with about 5,000 women dying from it. Cervical Pap tests are designed to identify pre-cancerous abnormalities in women, but conventional Pap smears have remained the same since 1950. The old technology is believed to be only 80 percent accurate.

With conventional Pap tests, doctors smear the cells on a slide and send it to a laboratory. With the ThinPrep test, the cells taken from the cervix are rinsed in a small vial of alcohol-based solution to preserve the cells.

The technicians then put the solution into a machine that prepares a thin, round sample on a slide. Next, an imaging machine examines the slides before they are sent to technicians for evaluation.

"The nice thing about it is it can work 24 hours a day, seven days a week, and it improves the process," Brewerton said. "We want to let our female patients know they are getting an improved Pap test because of the dual review - first by the machine and then by humans. That brings better service to the patient."

Five hundred slides a day: LDS Hospital leased the first computer in last spring and added another one in fall. With the two machines, the hospital has the capacity to screen 500 slides a day. Typically, the hospital receives 350 Pap smears per day from all over the state.

Only 5 percent of the Pap smears they receive are done the conventional way. The cytology department would like all tests to be done the new way, but some physicians are reluctant to change.

At the laboratory, the machines separate the blood and mucus from the cervical cells that are then tested for abnormalities.

Studies in the United States, Australia and Switzerland have shown that the ThinPrep test significantly increases the ability of the doctor and laboratory to identify abnormalities. One study of 6,747 smears found ThinPrep identified 65 percent more low-grade cervical lesions and 36 percent more high-grade lesions, compared to the conventional method.

Brewerton said patients are less likely to be recalled for testing due to the extra sensitivity of the ThinPrep test. The system also can perform additional tests out of the same vial for three sexually transmitted diseases covered in the conventional Pap smear: human papilloma virus (HPV) - also known as genital warts - chlamydia and gonorrhea.

Hidden dangers: HPV is the leading cause of cervical cancer and the most common sexually transmitted disease in the United States. It is dangerous because many people are unaware they have been exposed to it. The wart virus can show up months or years later, or symptoms never show up at all. In the latter case, sexually active people can unknowingly pass on the virus to partners.

Most women who develop invasive cervical cancer don't get regular Pap smears. Experts recommend women who have had normal tests get one at least every three years, but once a year is preferable.

"Women need to get Pap smears regularly," said Cynthia Pratt, of the LDS Hospital cytology team. "The important thing is to find abnormalities so the patient can be treated before it becomes malignant. As patients, you should ask your physicians about the type of testing they use."




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