Margaret,
This probably should be PCR which stands for Polymerase Chain Reaction...

It basically means they will test if a certain DNA sequence (ie HPV 16 etc) is present.
It is amazingly sensitive.
So the idea is they test the DNA of the cells and see if the sequence of the virus are there as well. It is a needle in the haystack thing.
This also points to the achilles heel of this test. You can test all you want and the result is negative unless you sample these cells that are infected by the virus. .... if you see your cancer then it is easy to know WHAT to test. Otherwise the question is which cells are your testing... anterior tongue, BOT, floor of mouth, cheek etc.


M