Papanicolaou test
Meaning of Papanicolaou test: One of the most effective cancer screening tests ever introduced, it finds changes long before they could become cancer, when they are simplest to remove.
Definition of Papanicolaou test
The Papanicolaou test is a screening examination in which cells are collected from the surface of the cervix and examined under a microscope for changes that could later develop into cancer. It is named after the physician who developed the method. The test looks for abnormal cells rather than confirming disease, so a concerning result leads on to further examination.
How is the sample taken and read?
A speculum holds the vaginal walls apart so the cervix can be seen, and a small brush or spatula sweeps the transformation zone, the ring where one type of surface cell gives way to another and where nearly all cervical cancer begins. The sample was once smeared straight onto a glass slide, which is where the older popular name came from. Most laboratories now rinse the brush into a preservative liquid instead, a method called liquid based cytology, which gives a cleaner preparation and allows other tests to run on the same sample. A cytotechnologist screens the slide and a pathologist reviews anything abnormal.
What do the results mean?
| Result | What it indicates |
|---|---|
| Negative for intraepithelial lesion or malignancy | No abnormal cells found |
| ASC-US | Cells look slightly unusual and the significance is uncertain |
| Low grade squamous intraepithelial lesion | Mild changes, usually tied to recent HPV infection, and frequently resolving without treatment |
| High grade squamous intraepithelial lesion | More marked changes carrying a greater chance of progressing if left |
| Atypical glandular cells | Abnormal cells from the glandular lining, which prompts wider evaluation |
How does it fit with HPV testing?
Almost all cervical cancer follows persistent infection with high risk types of human papillomavirus, so testing for the virus answers a different and earlier question than looking at cells. The virus test asks whether the risk is present; the cell test asks whether damage has already started. Programs combine them in different ways, some testing for the virus first and examining cells only when it is found, others doing both at once. Which approach is recommended, and how often screening repeats, is set by national guidelines and revised as evidence accumulates, so the arrangement differs between countries and over time.
What are its limits?
It examines the cervix and nothing else, so it does not screen for cancer of the ovary, the lining of the uterus or the vulva, and it is not a test for sexually transmitted infections. A single test can also miss changes that are present, if the brush missed the affected area or the abnormal cells were few, which is one reason screening repeats at intervals rather than happening once. Inflammation and infection can make cells harder to read, and a sample without enough usable cells is reported as unsatisfactory and taken again.
Also known as
Used in a sentence
The Papanicolaou test result prompted a referral for colposcopy to further evaluate the cervix.
Good to know
The Papanicolaou test samples surface cells of the cervix and screens rather than diagnoses, which distinguishes it from a cervical biopsy, where tissue is removed to establish what an abnormal screening result represents.