Pap smear
Meaning of Pap smear: Checking one organ for one kind of change, it is not a test for infections, for ovarian cancer, or for general gynecological health.
Definition of Pap smear
A Pap smear is the everyday name for the cervical screening test in which cells are brushed from the surface of the cervix and checked under a microscope. Smear refers to the original method of spreading the sample onto a glass slide; most laboratories now suspend it in liquid instead, so the name has outlived the technique it describes.
What does it actually check?
It examines the appearance of squamous and glandular cells taken from the surface of the cervix, looking for the changes that persistent infection with high risk human papillomavirus produces. Those changes develop slowly, typically over years, and that slowness is what makes screening worthwhile: an abnormality can be found and dealt with long before cervical cancer would appear. The abnormal cells cause no symptoms of their own, so how a person feels gives no indication of what the test will show.
What does it not check?
| Commonly assumed | What is actually the case |
|---|---|
| A screen for sexually transmitted infections | Chlamydia, gonorrhea, syphilis and HIV each require their own test |
| A test for ovarian cancer | The ovaries are not sampled, and no reliable screening test for ovarian cancer exists |
| A test for cancer of the uterus | The uterine lining is not sampled, though abnormal glandular cells sometimes prompt investigation of it |
| The same thing as a pelvic examination | The examination assesses the pelvic organs by feel; the smear is a laboratory test on collected cells |
| A diagnosis of cancer | It reports how cells look; examining tissue is what establishes a diagnosis |
What happens after an abnormal result?
Most abnormal results are not cancer and never become it. Mild changes frequently reverse on their own as the immune system clears the underlying infection, so a repeat test after an interval is a common next step. More marked changes lead to colposcopy, in which the cervix is inspected through a magnifying instrument after a solution is applied that makes abnormal areas stand out, and a small tissue sample is taken if anything suspicious is seen. Where high grade change is confirmed, the affected zone can be removed as a minor procedure. A result reported as unsatisfactory means the sample held too few usable cells and says nothing at all about what is there. The same principle is applied at other sites, including an anal version used in people at raised risk.
Also known as
Used in a sentence
The patient's routine Pap smear showed mild cellular changes that prompted further evaluation.
Good to know
A Pap smear screens the surface cells of the cervix and does not test for sexually transmitted infections or for cancer of the ovary or uterus, each of which requires separate evaluation.