If it's for pregnancy, your doctor should have known better than to test you after 3 days. The shot releases the hCG hormone into body and that's what tests look for, regardless of how it's in your body. The test came back positive because of the shot. It's far too early to be testing for pregnancy. They should have waited at least 14 days after you had the shot.
i had taken it for pregnancy..but i just want to know that is test is result of previous month pregnancy or current month? i m not able to undersatnd why the result came positive at that time.
Are you on fertility treatment? The only two hCG shots I know of is one to lose weight and another for women trying to get pregnant. Depending on how much you had, it's very possible that's why your test came back positive.