I had bleeding last week. going possibly on 8wks preg. i took preg test 8 days after i bled. if miscarriage happened how long does hcg level go down?

Not accurate method.: Using a home based pregnancy test is not an accurate method to determine miscarriage or keep tract of the progress of pregnancy. The best way is with a quantitative blood test which should be ordered by a GYN provider. My suggestion is to go and get seen examined and have lab ordered in order to give you definite answers.

It depends: How long for hcg to go down depends on how high it was and whether the miscarriage is complete or not. Pregnancy test is not a good way to know, since it can remain positive for many weeks after a miscarriage.