Cytology tests

What is cytology?

This page was reviewed under our medical and editorial policy by

Bradford Tan, MD, Chair, Department of Pathology and Laboratory Medicine, City of Hope Atlanta, Chicago and Phoenix

This page was reviewed on November 15, 2021.

Cytology, also called cytopathology, is used to evaluate individual cells or cell clusters to diagnose certain diseases, including some forms of cancer.

Cytology tests are designed to allow testing using a small sample with less pain than having to remove a larger volume of tissue.

Cytology tests for cancer

A cytology test is used to look closely at cells and body fluids. It may be helpful if a patient has cancer symptoms or is due for a cancer screening.

There’s a wide range of cytology test procedures. A Pap smear, which collects cells from the cervix, is one example. Removing spinal fluid by a lumbar puncture can provide cells for a cytology test.

A cytology test is different from a biopsy. During a biopsy, tissue from a certain area of the body is removed and analyzed for cancer. A cytology test removes and studies a fewer number of cells.

With a cytology test, the cytological morphology of the cells collected are studied under a microscope. The study of the cells is referred to as cytopathology.

Why are cytology tests done?

Care teams use cytology to diagnose, but also to screen for disease even before symptoms are noticeable. The test helps identify and diagnose cancerous and noncancerous cells. Test results may also help classify the disease.

If something is detected on a screening cytology test that requires further information, the doctor may order more tests, such as a repeat cytology or a biopsy.

When screening for cancer, the technician looks for cancerous or precancerous changes to cells. Precancerous cells are those that look abnormal but may or may not turn into cancer.

Doctors sometimes perform a biopsy in addition to cytology to confirm a diagnosis before proceeding to cancer care planning and treatments.

How is a cytology test done?

Doctors perform different types of cytology tests depending on the affected area of the body.

Body fluid samples: Fluids from body cavities may need to be removed for cytology testing. Cells from the following areas may be taken for examination:

  • Ascitic fluid, which is removed from the abdomen
  • Cerebrospinal fluid, also known as spinal fluid, which is removed from the space around the brain and spinal cord
  • Pericardial fluid, which is removed from the sac around the heart
  • Pleural fluid, which is removed from the space around the lungs
  • Sputum (also called phlegm), which are lung secretions, or mucus, collected during coughing
  • Urine, which is collected by a clean-catch urine sample in a doctor’s office

Fine needle aspiration: Classified as both a biopsy and a cytology procedure, a fine-needle aspiration involves the use of a thin needle on a syringe to remove fluid and small pieces of tissue from a tumor. If a tumor is near the surface of the body, the doctor may aim the needle by touch if the tumor may be felt. If not, an ultrasound or computed tomography (CT) scan may be used to guide the needle to the right location. With a fine-needle aspiration, the doctor may be able to make a same-day diagnosis. Sometimes, however, the needle doesn’t remove a sufficient amount of tissue for a definite diagnosis.

Scrape or brush cytology: This procedure involves scraping or brushing some cells from the organ or tissue that’s being tested. Some areas where doctors use scrape or brush cytology include the breathing tubes that lead to the lungs, cervix (for a Pap test), esophagus, mouth and stomach.

Swab: A swab is used to get fluid or secretions.

Washing: A washing involves removing fluid to collect cells from a hollow organ that were exfoliated.

For many cytology tests, no special preparation is needed. But patients should ask whether they need to do anything in advance before a particular procedure.

After a cytology test, doctor and patient should discuss the test results and whether additional follow-up testing is needed.

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