Urine & Blood Test?

I need to give blood and urine tests for some particular purpose, i want to hide my pregnancy.

if I change my urine with some one else, is it possible, that Doctor will come to know that urine and blood is not of the same person???
Please tell, if you really know

It's possible to switch out urine, people do that quite often actually. Just make sure the urine is warm but not too warm, if you are giving the sample while at the MD's office.
If you are bring the sample in from home, they will have no idea it's not yours. As far the blood test is concerned, they will take blood at the clinic so there is no way to switch that. Are you sure they're actually testing you for pregnancy? If it's for an employer they won't test for that.

No use cheating yourself,besides tests will lead you nowhere.
HAPPY NEW YEAR 2007.

I am a doctor, and I can tell you that there is no way, UNLESS they do a blood pregnancy test as well!!! which is highly unusual unless there is a strong suspicion for pregnancy with a urine that shows no pregnancy.

blood type and rh factor must be consistent with yours however I suggest you be straight with your doctor an insist that your confidentiality remain in tact

If you are submitting blood and urine tests for other reasons, (lets say a mandatory drug test) then the lab wont be testing for pregnancy. DONT switch your urine with someone else's....could cause more problems than you realize.