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Diagnosing diseases by looking at single cells and small clusters of cells is called cytology or cytopathology. It’s an important part of diagnosing some types of cancer.
Cytology tests are different from biopsy tests because only a few cells are needed, instead of a tissue sample. Compared to doing a biopsy, getting a cytology sample is usually:
The disadvantage is that cytology tests don’t always provide as much information as a biopsy. But in many cases a cytology test may be just as helpful.
Cytology tests may be used for screening or for diagnosis:
Some cytology tests are mainly used for screening, while others are used more often to diagnose cancer (see “Scrape or brush cytology” below). When cytology results show cancer, often a biopsy is also done to be sure before treatment is started.
Fine needle aspiration (FNA) uses a very thin, hollow needle attached to a syringe to remove a small amount of fluid and very small pieces of tissue from an abnormal area. This is sometimes considered a cytology test and sometimes a type of biopsy. It’s discussed in How Is a Biopsy Done?
Different types of body fluids can be tested to see if they contain cancer cells. Some of the body fluids that can be tested in this way include:
Another way to get cytology samples is to gently scrape or brush some cells from the organ or tissue being tested. (This is also sometimes called a brush biopsy.)
An example of a cytology test that samples cells this way is the Pap test. For this test, a small spatula and/or brush is used to remove cells from the cervix (the lower part of the uterus or womb).
Many other parts of the body can also be brushed or scraped to collect cells for testing, include the mouth and throat, esophagus (swallowing tube), stomach, bile and pancreatic ducts, and the breathing passages in the lungs.
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.
Last Revised: August 1, 2023
American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.
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