PCR Test
Reviewed
PCR (polymerase chain reaction) tests are a reliable and accurate way to diagnose certain infectious diseases, some types of cancer, and certain genetic changes. They detect small amounts of genetic material (DNA or RNA) from a pathogen or abnormal cell in a sample. The test amplifies the genetic material to make it easier to detect. Results are typically qualitative (detected or not detected). Because PCR tests can find disease early, they play an important role in preventing the spread of infections.
Preparation and collection
No special preparation is needed.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- May detect genetic material from a past infection even after you are no longer infectious (false-positive for active infection).
- A poor sample (e.g., not swabbing both nostrils or not rotating the swab) can lead to a false-negative result.
What to do next
Your healthcare provider will interpret your result in the context of your symptoms, exposure history, and other tests. Follow-up may include additional testing or treatment if an infection or genetic change is detected.