They are pretty accurate - it would be unusual for lab error but never impossible.

Considering you had a D & C and you had a negative result - less than 5 is considered negative in most labs. It would be unlikely for any placental tissue to be left over and growing.

Less than 20 isn't called pregnant either - you need to wait. Going from 3 -12 isn't such a worry if you were pregnant as implantation could have just occured.

Another BHCG QUANTATATIVE level done in another 24 hours will giive a better picture.

Thinking of you honey..