A chemical pregnancy takes place before a fetus can be detected by ultrasound, and not too early for most pregnancy tests to detect levels of human chorionic gonadotropin (hCG). HCG is a pregnancy hormone the embryo produces after implantation. Your medical practitioner can confirm a chemical pregnancy by running a blood test for it.
Most of the time, this hormone is only inside a woman’s body during pregnancy, so a pregnancy test is usually fairly conclusive. Because most pregnancy tests can detect even very low levels of hCG in the urine, a pregnancy test taken in the days or immediate weeks after the miscarriage can show a false-positive test result, but this happens rarely.
To simplify, this means that the test can show that you are pregnant even if you’re not. A woman can have a false-positive test result if protein or blood is present in the urine. Certain drugs, such as anticonvulsants, tranquilizers, and hypnotics may also cause the test to read the false-positive result.