What is a Pap Smear?
The cells from the surface of the cervix are shed into the vaginal fluid. A Pap smear is a smear of these secretions collected during an internal examination of a woman.
The fluid is spread in a thin layer over a glass slide. Because of this spreading action, the test is called a smear. It is fixed in alcohol, stained with special dyes and examined under a microscope.
The collection of vaginal fluid itself is painless.
The Pap smear is named after Dr. Papanicolaou, a Greek doctor who was among the first to describe the relationship between the appearance of cells in the vaginal secretions and the state of the cervix.
What diseases can be diagnosed by a Pap smear?
A number of diseases, including cancer of the uterus and ovary. But the most important is cancer of the cervix.
How does a Pap smear detect cancer of the cervix?
The normal cervical smear should contain a mixture of cells from the outer surface and central canal of the cervix. The cells are examined for signs of any changes. The size, shape and absorption of each cell changes when a disease is present. Vaginal infections cause swellings which produce minor changes.
Cancer will produce an enlargement of the nucleus and darker stains in the different parts of the cell.
The normal Pap smear is described as Class 1. If there are changes caused by swelling, the smear is a Class 2. When there are changes that indicate cancer, the report will be Class 3, 4 or 5, depending on the severity of change.
How does the Pap smear detect cancer of the ovary?
In about 20 per cent of cancers of the ovary, some cancer cells are shed by the ovary. They pass along the Fallopian tube and uterine cavity into the upper end of the vagina and can be detected by a Pap smear. This 20 per cent pick-up rate is not good enough as a dependable method of screening for ovarian cancer.
On the other hand, the pick-up rate for cervical cancer is 95 per cent.
The better method to screen for cancer of the ovary is an annual pelvic examination. The doctor checks the appearance and texture of the cervix, the size and position of the uterus, and for enlargement of the ovaries.
A Pap smear should be taken once a year for women with no complaints.