Alternative Names Pap test, Papanicolaou test, Pap screening
Definition This test involves examining a random sampling of cervical cells under the microscope. The cells are obtained by scraping the external surface of the cervix. A Pap test is done to detect early precancerous cells changes, which is known as cervical dysplasia.
Because cervical dysplasia is a change that happens before cancer actually occurs, there are typically no symptoms. This is why Pap smear screening is crucial in all sexually active women
The Pap smear was developed more than 50 years ago. Since that time, deaths from Cervical cancer have dropped significantly. The rate of precancerous changes, or cervical dysplasia, has increased, however. This probably has to do with the rise in the number of cases of human papilloma virus (HPV) infection, which is associated with development of cervical cancer. Women also tend to have more sexual partners than decades ago, which puts them at increased risk. Rates of cervical cancer are higher among poor women and among women who have had multiple sexual partners at an early age.
cervical cancer is the second most common cancer of the reproductive tract in women. The disease most often strikes women between the ages of 30 and 55.
A cervical cell goes through precancerous stages for months to years before becoming an invasive, or malignant, carcinoma. Treating the disease at the precancerous stage can prevent the further development of cervical cancer.
The cells of the cervix behave very much like skin cells. Exposure to potential environmental toxins, viruses and bacteria can cause abnormal changes. The earliest change that occurs in the cervix is called mild cervical dysplasia. This condition may progress to more severe changes known as carcinoma in situ. Finally, the abnormal cells progress to invasive cervical carcinoma, which invades the deeper layers of the cervix or spreads to adjacent structures. The number of layers of cervical cells that are affected marks the progression from mild to more severe changes.
Three types of cervical cells can develop abnormalities. Ninety percent (90%) of the time the cancer arises in skin-type epithelial cells called squamous cells. Cancer in glandular cells is called adenocarcinoma, and adenocarcinomas account for 20% of cases. Rarely, muscle cells are the source of the cancer.
Who is a candidate for the test? Screening should begin within 2 years of sexual intercourse. It should be done every 2 years. Women should continue with Pap testing into their 70's regardless of sexual activity. Women may need more frequent screenings if they are at high risk. High risk factors may include:
How is the test performed? The first step is for the doctor to perform a pelvic examination. A speculum is placed in the vagina. This instrument allows the doctor to see the interior of the vagina and the cervix. A sterile, small brush is used to take a sample of cells from the internal opening of the cervix. A small wooden spatula is used to scrape the outside of the cervix. These two scrapings are placed on a glass slide. The slide is reviewed under a microscope to analyse the cervical cells.
What is involved in preparation for the test? A Pap smear should be performed during the weeks before the start of menstruation. Women should not douche, have sexual intercourse, and use intravaginal creams, a diaphragm, or tampons for 24 hours before the test. To minimise discomfort, a woman should empty her bladder just before the examination. This will also allow the doctor to more accurately check the uterus and ovaries.
What do the test results mean? A normal Pap smear indicates no abnormal cells or evidence of inflammation. The presence of abnormally growing cells on the surface of the cervix may be reported as an abnormal PAP smear. Categories of cell changes include:
ASCUS (atypical squamous cells of undetermined significance)
AGUS (atypical glandular cells of undetermined significance)
LSIL (low grade squamous intraepithelial lesion-possible HPV or CIN I)
CIN I (mild dysplasia)
CIN II (moderate dysplasia)
HSIL (high grade squamous lesions, CIN II, CIN III, CIS)
CIN III (severe dysplasia) (carcinoma in-situ)
All these changes are within the superficial layer of the cervix. The cancer has not spread more deeply into the cervix or to other organs.
A woman who has had two or more abnormal Pap smears (ASCUS, CIN I or HPV changes) should undergo colposcopy. This is a test in which the cervix is viewed with a special lighted microscope. A cervical biopsy may also be needed. A PAP smear indicating more severe cervical changes of HSIL (CIN II, CIN III, CIS or possible invasive carcinoma) requires immediate colposcopy and biopsy.
Author: David T. Moran, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 6/06/2005 Contributors Potential conflict of interest information for reviewers available on request
