What to think about
The most common screening test for hepatitis C is a blood test for antibodies to the virus. A positive test indicates whether a person has been infected with hepatitis C but it does not distinguish between previously cleared or current infection.
About 20% of people who have been infected with hepatitis C will clear the virus at the acute stage. However, in general these people will still have positive antibody results.
It can take up to 3 months for antibodies to hepatitis C to show up following infection. Therefore, in patients whose exposure has been recent and whose first test is negative, the hepatitis C antibody test should be repeated 3 months after the last possible exposure in order to avoid misdiagnosis during this ‘window period’.
If the antibody test is confirmed as positive, the next steps are to establish if the virus is still present, and if so to diagnose the extent of the underlying liver disease. To do this further tests are required.
A PCR test will identify current circulating virus. More sophisticated tests are available to identify the genotype of the virus and to assess the viral load.