Dr. Tony Holohan:

Figures are used to describe the performance of this test and they are around 60% to 75%. We say about 70%. What that means is in a situation where something is present and one is trying to find it, there is a 70% chance that it will be picked up with the test and a 30% chance that it will be missed. That is where it is there - the finding is there - but when the great majority of women have a smear, their cervix and cells are normal. The following question then arises. If a person has a normal test, how certain can that person be that that normal test is actually correct and the test has been performed well? The answer in that situation is over 99% of the time.