Is it possible to be pregnant and have an hpt be positive and a blood test be negative?

it's not very likely, blood tests are very accurate and HCG (pregnancy hormone) shows in the blood before in the urine. HPT's are not as accurate and sometimes can provide a false positive result, though it's not all that often. Sometimes if you look at the test after the time allowed in the instructions you will see a false positive line. ~pawsalmighty