What is PCR (RNA) testing?
RNA testing refers to an advanced technology that is used to detect ribonucleic acid from the hep C virus (also called HCV).
Several types of RNA technologies exist with the most commonly-used version being the Polymerase Chain Reaction (PCR) test. Less commonly used versions include the transcription mediated amplification (TMA) test – which is used as a screening test by Australian blood banks, and the branched chain DNA (bDNA) test which is generally used as a research tool.
Unlike the HCV antibody test that looks for signs that the body has at some time mounted an immune response to HCV, the PCR test looks for current presence of the virus.
With hep C, there are 3 types of PCR tests:
- PCR viral detection test: it looks for the virus
- PCR viral load test: it looks for the virus and estimates how many HCV viruses per millilitre of blood
- PCR genotype test: it looks for the particular genotype of HCV.
PCR viral detection test
The basic PCR viral detection tests are used to confirm the actual presence of HCV. This is especially useful in the case of people who have an inconclusive (unclear) HCV antibody test, or with people who have signs they may have previously cleared their hep C (i.e. their liver function tests are consistently normal and they experience no symptoms of hep C illness).
PCR viral detection tests are also used to confirm HCV status when a person has immunodeficiency (e.g. due to HIV infection) as this condition can be associated with a false negative HCV antibody test result.
PCR viral detection tests are also used at 3 weeks after a transmission risk incident (e.g. a needlestick injury) to check if a person has contracted hep C.
The test is also used to determine someone’s response to treatment. Cure is measured by having a negative PCR test result at 12 weeks after treatment finishes.
PCR viral load testing
PCR viral load testing estimates the amount of hep C virus circulating in someone’s blood.
PCR genotype testing
PCR genotype testing determines which type of treatment a person will be offered.
Availability – PCR viral detection test in hep C treatment (69445)
Detection of hepatitis C viral RNA in a patient undertaking antiviral therapy for chronic HCV (including a service described in item 69499). To a maximum of 4 of this item in a 12 month period.
Availability – PCR viral load tests (69488)
Quantitation of HCV RNA load in plasma or serum in:
(a) the pre-treatment evaluation, of a patient with chronic HCV, for antiviral therapy; or
(b) the assessment of efficacy of antiviral therapy for such a patient.
Availability – PCR genotype tests (69491)
Nucleic acid amplification and determination of HCV genotype if the patient is HCV RNA positive and is being evaluated for antiviral therapy of chronic HCV. To a maximum of 1 of this item in a 12 month period.
Availability – PCR viral detection test in diagnosis (69499)
Detection of hepatitis C viral RNA if at least 1 of the following criteria is satisfied:
(a) the patient is hepatitis C seropositive;
(b) the patient’s serological status is uncertain after testing;
(c) the test is performed for the purpose of:
- determining the hepatitis C status of an immunosuppressed or immunocompromised patient; or
- the detection of acute hepatitis C prior to seroconversion where considered necessary for the clinical management of the patient;
To a maximum of 1 of this item in a 12 month period.
Hep C transmission and PCR in health care settings
The NSW Ministry of Health recommends that following needlestick and other sharps injury in health care settings, voluntary PCR testing of source individuals should be done.
In NSW, health care workers who perform exposure prone procedures must be aware of their HCV PCR status. Those who are HCV PCR positive must not perform exposure prone procedures (see NSW Ministry of Health circulars, PD2005_311 and PD2005_162).
Exposure prone procedures are those with potential for a health care worker to bleed into a patient as the result of a sharps injury, e.g. surgical procedures in body cavities. The NSW Ministry of Health has a longer and more precise definition to guide health care workers (see above circulars).
After catching hep C virus, it takes two weeks before it will show up in a PCR test (this is called the PCR window period).
HCV transmission risk
Whether PCR positive or negative, the key HCV transmission prevention message will always remain “be blood aware and avoid blood-to-blood contact”. In any situation involving potential blood-to-blood contact, it’s important for everyone to assume that any blood is potentially infectious. Whether someone has hep C or not, there is the additional risk of contracting other bloodborne infections, e.g. HIV or hepatitis B.
For more information about anything in this factsheet, phone the Hepatitis Infoline on 1800 803 990 or go to www.hep.org.au
This factsheet was developed by Hepatitis NSW. It was reviewed by the Hepatitis NSW Medical and Research Advisory Panel with assistance from ASHM (Australasian Society for HIV Medicine).