What it Means when Your Urine Test is Positive But Your Blood Test Is Negative

Most women rely on urine pregnancy test home kits to find out whether they are expecting. However, the results of the home test may not also be synonymous with the results of a blood test which is done in the lab or at the doctor’s office. If a home pregnancy test kit revealed positive, but the blood test says negative, or vice-versa, a woman may need to re-take both tests. Home pregnancy kits that make use of urine samples are generally 97% accurate when used correctly, and when performed timely. A lab-based blood test is more accurate, but this does not necessarily mean more sensitive. The reliability of blood tests also depend on the accuracy of the testing laboratory, and the methods used to gather results.

When a home pregnancy kit shows you a positive sign, it means there is HCG in your urine. HCG is a pregnancy hormone that is released by a placenta, so traces of this in your urine means you are pregnant, or have been recently become pregnant. It may also show up on your urine if you are taking a medication that contains this hormone. Medications that do are usually those used to treat infertility.

Blood tests also check on the levels of HCG in the blood, but in addition they also determine how much hormone there is. This helps a doctor estimate how old the pregnancy is, and if it is developing as expected.

These are common reasons why a blood test and a urine test done at home may not match:

1. You may have had a false positive result. This means you may have been pregnant, but encountered a miscarriage that took place in the form of a period. When this happens, the traces may still be in your urine, but is slowly leaving your blood, or vice-versa.
2. Medications may cause a blood test to say that a woman is not pregnant when she really is. Specifically, fluid pills, or diuretics, which increase a woman’s body’s production and utilization of water, have this effect.

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