False Positive Pregnancy Blood Test Results

Taking a home urine pregnancy test.

False positive pregnancy blood test results.

A false positive test result a positive human chorionic gonadotropin hcg test result when you are not pregnant can occur for a variety of reasons. Chemical pregnancies are common and often occur for no reason. Human blood normally contains many different types of antibodies. First a quick summary.

A false negative test is negative but you re pregnant can occur if the blood pregnancy test was performed too early. Molecules made by our immune system that identify and neutralize invaders such as bacteria and viruses. As with urine home pregnancy tests it is possible to end up with false results both negative and positive from a blood pregnancy test. There is another cause of false positive hcg test results that is unique to blood samples.

Intact hcg reduced the number of false positive pregnancy test results from 13 to 1 a 92 reduction 95 ci 64 99 corresponding to a reduction in the false positive rate from 38 95 ci 22 56 to 3 95 ci 1 15. If there s a false positive test result the test indicates that a woman is pregnant when in fact she isn t. After an abortion or miscarriage a home pregnancy test may produce a false positive result since the levels of hcg in the body may still be relatively high. But they can cause the body to start producing hcg which could get picked up on a pregnancy test and cause a false positive reading.

Other medications can also cause false positive pregnancy tests. It may cause a false positive reading on an at home pregnancy test particularly if the test is taken too early. A phantom hcg causes a positive blood pregnancy test without being pregnant. Most over the counter pregnancy tests measure the levels of hcg in a woman s urine.

Though very rare a false positive blood test happens with a low positive blood pregnancy test the urine test is negative and there is no pregnancy.