The Pap Smear Test is a test for the diagnosis of cancer. It is most commonly used to detect cancer of the cervix and uterus, though it may be used to discover cancer of some other organs. The test, properly known as the Papanicolaou smear test, is named for the Greek-American physician George Nicholas Papanicolaou, who developed the technique. It is an important advance in medicine because it detects the earliest and most easily curable stage of cancer.
The Pap smear test is based on the fact that all types of cancer, even in their earliest stages, shed atypical cells. In the case of cancer of the cervix or uterus, these liberated atypical cells float singly or in groups into the secretions of the uterus, cervix, and vagina and mix with the normal cells present. The physician uses a special instrument to rub the surface of the cervix to obtain a sample of cells. Specialists stain the smear and study it microscopically to determine the nature of the cells present.
The smears are generally interpreted in five classes: class I, the absence of atypical cells; class II, the presence of some atypical cells but no evidence of cancer; class III, the presence of cells suspicious of cancer; class IV, the presence of cells strongly suggestive of cancer; and class V, the presence of cells that are definitely malignant.
Pap smears do not, however, provide a final diagnosis, and they are not 100% accurate. They are more reliable for detecting early cancer of the cervix than for cancer of the body of the uterus, largely because it is more difficult for the physician to obtain cells from the body of the uterus. If cancer is suspected, a biopsy is performed—that is, a small piece of uterine tissue is surgically removed and studied.
A Pap smear test should be made at least once a year on all women over 20 years of age, including pregnant women, and preferably twice a year on all women over 35. The procedure is easily carried out in a physician's office, and it is painless. A woman planning to have a Pap smear test should not douche the day before or the day of the test nor use a contraceptive jelly or other substance that may affect the cells or lining of the genital tract.