83 days late, my urine test was ng for preg, but the last time i was preg. i could only tell through blood and i was 10 wks. why is that?

Sometimes: Even the most morning/concentrated urine sample may not contain enough HCG to turn the test positive. Either way, please see your doctor and get a blood test.

Pregnancy tests: Different tests detect different parts of the bhcg molecule and sometimes the molecule that a patient has will not react with certain brands but will with others. If you think you are pregnant, see a doctor and get the appropriate testing.