Cytology generally refers to the study of cells found in living things. Diagnostic cytology is the process of studying cells to identify diseases. Procedures to obtain cell samples to perform cytological evaluations are varied, but usually involve taking either a sample of body fluids or a scraping of cells from body tissue. Diagnostic cytology may be used to help identify various types of cancer and certain infections.
The human body is made up of many different types of cells, from immune system and blood cells found throughout the body to specialized cells found only in certain organs. When viewed under a microscope, all types of cells have certain physical characteristics that differentiate them from other types. Certain diseases and infections can affect how cells function and look, or where they are present in the body. Diagnostic cytology can help pick up on these changes and determine what disease is causing them.
There are several different procedures that can be used to obtain a sample of cells from the body for diagnostic cytology testing. The method typically depends on the area being studied. For example, if a health-care provider suspects a problem in the bladder or urinary tract, a urine sample may be taken for further testing. If a problem is suspected in tissue that can be accessed relatively easily, such as the mouth or cervix, a scraping of cells may be taken directly from the tissue this area.
Cervical cells are one of the common subjects of diagnostic cytology. A scraping of cervical cells, commonly known as a pap smear, is frequently done to screen for cervical cancer. This same test may also diagnose certain infections, such human papillomavirus. In general, cells scraped from the surface of the cervix in a pap smear are mounted onto a slide and dyed with a special chemical so they can be easily seen under a microscope. A diagnostic cytologist typically then evaluates this prepared sample to see if the cells present are normal or show changes that could be indicative of cancer or infection.
Other types of cancer and infections may also be diagnosed via diagnostic cytology. For example, bladder and kidney cancer may be diagnosed by the evaluation of cells obtained from a urine sample. An infection known as bacterial meningitis may be found by cytological evaluation of cerebral spinal fluid. In some cases, diagnostic cytology can only identify that something is not normal. Other types of testing, such as DNA tests or tissue biopsies, may be needed to confirm the actual disease or infection.