They are not a sensitive as the ones you can get that test sooner. I work at a doctors office and only started showing up positive on their tests about 1 - 1 1/2 weeks after I got my BFP at home. I got mine with the Answer Early Results and then confirmed by a First Response Early Response and Clear Blue digital.
Actually the tests at the Dr's office are not very sensitive at all .You are better off usuing a first response at home. That is the one I have found to be the most sensitive =)
From what I understand the Dr's test are identical to the dollar store tests.