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Why Was My Home Pregnancy Test Positive, But My Blood Test Negative?

Typically, after you get your positive pregnancy test, or tests if you are a testaholic, the next step is usually a visit to your doctor for confirmation. If your pregnancy blood test has a negative result, you need to have another blood sample drawn. Home pregnancy tests are very accurate, when you follow the directions exactly. Blood tests tend to be more accurate, but are not necessarily more sensitive. The blood test results received can vary depending on the lab, methodology and technique used to perform the test.

Quantative blood tests measure the exact amount of hCG (human chorionic gonadotropin) in your blood and can pick up very low level of hCG present.

Quantitave blood tests simply tell you if you are pregnant or not, but not how much hCG is in the blood sample.

There can be a couple of reasons why you would get a positive urine based pregnancy test but have a negative, not pregnant, blood test result.

Home pregnancy tests, on the market today, can be very, very sensitive. Depending on what brand you are using, there is a possibility that your test picked up a level of hCG that is below what the lab, processing your blood sample, considers a positive result. The typical cut off levels for a positive, blood based, pregnancy test are typically 5, 10 and 25 units of hCG. If your home pregnancy test picked up a hCG level of 10 or less, but the lab considers a 25 unit level a positive test, you will get conflicting results.

Here are a few reasons why there was a discrepancy in your urine and blood test results:

False Positive Home Pregnancy Test

Home pregnancy tests are usually very accurate. There are times when this is not the case though. False positive test results can happen if the user reads the test beyond the time frame specified in the test instructions. The tester erroneously assumes that they received a positive pregnancy test result, when it was actually a non pregnancy related chemical reaction that was occurring beyond the testing time frame. In rare cases, an extremely rare form of cancer can cause a positive result on your pregnancy test as can some medications.

Qualitative and Quantitative Pregnancy Blood Test Results

For both types of blood tests, the results may negative, even if you are pregnant, if your blood was drawn too early and your hCG level was below what the lab considered a positive result. You can also get a negative result if the lab did not process the sample correctly.

With the quantitative blood test, an ectopic pregnancy or a miscarriage could be the cause of lower than normal hCG levels. Further testing by your doctor can determine if either of these issues could be the cause of a negative blood test.

  • tara127

    a about a month ago i took a hpt it come positive i went to the doctor and got a blood test that come back negative i was 6 days late for my period 3days after i went to the doctor i got my period after my period i notice that my breast were heavy and full so i pushed on them milk started coming out this month i was 4 days late and only had my period for 3 days and my breast a still leaking can you help

  • Confused

    4 hpt and all positive – 2 different brands. @ 4 weeks did bloods and negative. Came home and have since done another 6 test over the last 3 days (1 first in the am and the 2nd in the evening) again all positive. I would be about 5 weeks, maybe 4 depending on my cycle. No blood or spotting. Tender breast, sore lower back, heavy pelvis. This would be my 3rd pregnancy. Thoughts?

  • http://www.babyhopes.com/ Vickie B.

    Blood tests can be wrong. It would be best to assume you are pregnant and treat yourself as if you are. Give it a week or two and then go back to the doctor for another blood test and be sure to keep track of when you were getting the positive tests and the brands you are using. If you keep getting positive hpts, and another blood test still shows a negative, an ultrasound at around 6 or 7 weeks should be able to detect that you are pregnant.

Last modified: March 19, 2014

The information provided here should not be considered medical advice. It is based on the average experience of women trying to conceive and may not be what you may be experiencing. It's not meant to be a replacement for any advice you may receive from your doctor. If you have any concerns about your cycle or our ability to get pregnant, we advise you to contact your doctor.