Can a blood pregnancy test be wrong?

Can you have an indeterminate blood pregnancy test and not be pregnant?

• granted i was only 3 days late...two home tests were extremely faint, went into my ob and they full exam because i hadnt been in awhile and everything felt normal and fine, the urine test there was extremely faint as well so they said they could order me a blood test if i wanted and that would be definitive, so we did, the next day they called me and the nurse said it came back as indeterminate and more than likely i was just late, ironically enough i started my period that day, cramps and full red menstral blood. americanpregnancy.org, state there is a difference between spotting when pregnant blood and menstral blood. so it was definantely period blood, but i guess with four indeterminate tests i am somewhat still scared and cannot find anything online about wether or not an "indeterminate" blood test can mean you are not pregnant....my doc's office was actually very rude when the nurse called to tell me and she kind of laughed at my questions... like after she said youre prebably just a few days late i told her i started and asked if that was good and she said yes that means youre not pregnant laughing...so any help would be great! thanks

• Answer:

  That sucks that she was rude, but generally you can trust what nurses/doctors say. It is their job, after all. (I'm in a similar position - I've been spotting in the middle of my pack of pills for the first time for about 5-6 days and I called twice and the nurse said I should still be protected. It's difficult, but I'm really trying to trust what they say...) Plus, anyway, if you had a real, full, red period, that's enough indication that you aren't. Or perhaps you miscarried if you were. Odds are, you're not pregnant now.