Biopsy Vrs Bloodwork

So I now have one more week before my biopsy, the waiting really sucks, regarless of the results I am going gluten free. I read on here how inconclusive the results can be for the biopsy, and that really blows my mind as the doctors say that the biopsy is the only way to get a 100% true diagnosis. Then what are the results from the blood work worth. I mean if someone has High blood work and the biopsy is negative then what are you supposed to do.
This really sucks not knowing, Well I mean I know myself but the doctors think that the biopsy is the only thing to confirm it.