Wikipedia says:
The polymerase chain reaction (PCR) is a technique in molecular biology to amplify a single or few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence.
Practically it is means the test measuring your viral load. According to some, the best available test is LabCorp NGI QuantaSure. If you taking a treatment for hepatitis c you should test your viral load within 1 month of a treatment (tx) -- it is your baseline, and then, the standard is 4wks, 8 wks & 12 wks. The soner you are undetactable (UND) the better. After 4 weeks it's called RVS (Rapid Virological Response) after 12 wks it's called EVR (Early Virological Response). TAccording to some available data the SVR (Sustained Virological Response) is best when you first achieved RVR and then in proportion EVR. SVR is what you want -- it means you didn't relapse.
A good page with all this in one spot is right here:
http://www.medhelp.org/health_pages/Hepatitis/Common-Hepatitis-C-Acronyms/show/3?cid=64
It's also available on this page in a box on the right hand side called 'most viewed health pages'.
PCR stands for 'polymerase chain reaction', and is another name for a viral load test.
--Bill