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.

PCR viral load testing

PCR viral load testing estimates the amount of hep C virus circulating in someone’s blood. This test can help in determining someone’s response to treatment and, post-treatment, whether they are cured. Tests are done just before and then within weeks of starting treatment. Cure is measured by having a negative PCR test result at 12 weeks or 6 months (depending on your treatment regime) after treatment finishes.

PCR genotype testing

PCR genotype testing determines which type of treatment a person will be offered. People with genotype 1, 2 or 3 will be offered direct acting antiviral treatment from 1 March 2016. People with genotype 4 or 6 are offered Sovaldi ® taken with pegylated interferon and ribavirin treatment.

Availability – PCR viral load tests (69442)

Medicare funded viral load testing is made available in the pre-treatment evaluation or the assessment of efficacy of antiviral therapy of a person with chronic hep C – where any request for the test is made by or on the advice of the specialist or consultant physician who manages the treatment of the patient with chronic hep C (including a service in item 69444 or 69445).

NB: not more than 2 tests in a 12 month period.

Availability – PCR genotype tests (69443)

Medicare funded genotype testing is made available if:

a) The person is HCV RNA positive and is being evaluated for antiviral therapy of chronic hep C; and

b) The request for the test is made by, or on the advice of, the specialist or consultant physician managing the treatment of the person.

NB: not more than one test in a 12 month period.

Availability – PCR viral detection test in diagnosis (69444)

Medicare funded RNA basic detection (PCR) testing is made available if at least one of the following criteria is satisfied:

a) the person is HCV antibody test positive; or

b) the person’s HCV status is uncertain after testing; or

c) the test is performed for the purpose of:

  1. determining the HCV status of an immuno-suppressed or immuno-compromised person
  2. the detection of acute hep C (prior to seroconversion) where considered necessary for the clinical management of the person.

NB: not exceeding one test in a 12 month period.

“HCV antibody positive,” means two different assays of hep C antibodies are positive.

“HCV antibody status is uncertain,” means any result where two different assays of hep C antibodies are inconclusive.

Availability – PCR viral detection test in hep C treatment (69445)

Medicare funded RNA basic viral detection tests are made available for people undertaking antiviral therapy for chronic hep C (including a service described in item 69444).

NB: not exceeding 4 tests in a 12 month period.

Hep C transmission and PCR in health care settings

In regards to needlestick and other sharps injury in health care settings, attaining voluntary PCR testing of source individuals is recommended as a NSW Health recommendation.

In NSW, health care workers who perform exposure prone procedures must be aware of their HCV status. Those who are HCV PCR positive must not perform exposure prone procedures (see NSW 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 Department of Health has a longer and more precise definition to guide health care workers (see above circulars).

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.

Last Reviewed: 12/01/2016

Reproduced with kind permission from Hepatitis NSW.



References

Hepatitis NSW. Hepatitis factsheets: PCR testing. Last updated 12 Jan 2016. https://www.hep.org.au/factsheet-pcr-testing/ (accessed Feb 2016).