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



Pregnancy test

 

It can be extremely frustrating when your home pregnancy test is positive but a blood test taken at your doctor’s office comes back negative. However, there are a few reasons why this would occur.

Remember that all home pregnancy tests are roughly 97% accurate when they are performed correctly. The U.S. Department of Health and Human Services’ Office on Women’s Health provides a few notes on how best to take a home pregnancy test:

  • Choose your home pregnancy test wisely. Some have a lower sensitivity level than others. This means that those tests will be able to detect hCG in your urine early on in your pregnancy.
  • Before using a home pregnancy test, also check the expiration date and read the instructions completely. Their research suggests that you wait for at least 10 minutes before checking the results.
  • Each day that you are pregnant, the amount of hCG in your urine continues to increase. Therefore, if you were to take a test immediately after the first day of your missed period, there will not be enough hCG in your urine yet to really show up on the test. Plenty of home pregnancy tests state that they are 99 percent accurate when used on the first day of a missed period. Nevertheless, research today indicates that most of these tests are not truly capable of detecting low levels of hCG that is typically present in urine this early in a pregnancy. Even if they did, the results are usually very faint. It is better to take a home pregnancy test at least one week after you have missed a period. In addition, testing with your first morning urine can help improve the test’s accuracy.

Receiving a positive result on a home pregnancy test simply means that there is a presence of hCG in your body and is typically a sign that you have become pregnant. However, that result could be a false positive; meaning that even though it is positive, you are actually not pregnant. False positives, according to WebMD, can occur if you have blood or protein present in your urine. There are also certain types of drugs, like tranquilizers, anti-convulsants, and hypnotics, which can cause false-positive test results on a home pregnancy test.

Blood tests taken at your doctor’s office are thought to be more accurate than home pregnancy tests, although they are not necessarily more sensitive. The blood test results are contingent upon the method and technique of how the blood was drawn, transported, and tested, as well as upon the lab itself.

A quantitative blood test, which is sometimes referred to as a beta hCG test, measures the exact units of hCG present in your blood, even the most miniscule amount. A qualitative hCG blood test, will simply provide a yes or no answer on whether you are pregnant.

Each lab varies as to what it considers a positive pregnancy test with common cutoffs for positive blood tests for pregnancy being 5, 10, and 25 units. Any level that is under five is considered negative, and a blood test that is only triggered at 25 units of hCG is not any more sensitive than several of the home pregnancy tests.

However, a qualitative pregnancy blood test may provide a negative result even though you are pregnant if you take any diuretics as they can interfere with the test results. The timing of this test is also important, as it will only show a positive after 7 to 10 days after you have become pregnant.

A quantitative pregnancy blood test is also affected by the use of diuretics, but it can fail to detect hCG even when you are pregnant if it is taken too early, or if the hCG levels are too low. Keep in mind that it does take at least 7 days after fertilization for this type of blood test to become positive. Very low hCG levels can be the result of an ectopic pregnancy, a miscarriage, or an abortion.

It is highly suggested that you wait a few more days before taking another pregnancy 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.

  • Dee

    Did any of you actually end up being pregnant the same thing is happening to me? Would love to hear if you had a success story.

  • Courts

    I dunno if I am much help am one day before my period 4 home preg test postive had a blood test done on the 29th but neg In blood work but all my preg test have been after the blood worth by one day two days and today the test where two first responses and two digital clear blue so I am confused and a little upset

  • Guest

    Can caffeine effect a blood test?

  • Meowmeow13

    I had a negative blood test and 6 positive urine testsl went today for sonogram. Nice loud heartbeat and could see baby moving! Turns out I’m 8 weeks!
    Moral of the story, labs and drs offices mess up!

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

    No caffeine does not affect the results of a blood pregnancy test or a urine based pregnancy test.

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

    Congrats!

  • BabyT

    I got couple of positive home pregnancy test and then my period was 3days late so when I saw I went to the dr and did a blood test wjich came back negative. Im off my period and im cramping and nauseated.. am I pregnant or crazy

  • BabyT

    Were u pregnant after all

  • BabyT

    So are u pregnant??

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

    If you are getting negative pregnancy tests now, I would guess that you are not pregnant. Unfortunately, if you got positive results on pregnancy tests, you were probably pregnant but had an early miscarriage if pregnancy tests are not showing as a positive now. If you take another test and it does show a positive, I’d head back to the doctor and ask for another blood test as sometimes labs have errors.

  • BabyT

    Thanks

  • babec

    pls help me calculate dis i saw my priod last month june 6th and it came out by july 12th but did not flow wel as befor i did a urina test it show positive while blood is nagetive what is problem with me pls help me am not my self i need an aswer

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

    Are you still getting positive urine pregnancy tests?

  • HeatherLeigh

    I took 5 hpt all positive. Went to the doctors offoce, negative. I’m confused I feel pregnant… but not?

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

    It could be that the hcg level was so low that the blood test didn’t pick it up. Try taking another home pregnancy test (or several over time), if they turn positive make another appointment with your doctor.

  • Caitlin

    My last period was June 1st. My period has always been on time I was just so buys with work and my 7 month old to realize my period was late. I took a urine test. It was positive. Bought another brand. Also positive. Went to an urgent care for bloodwork to try to estimate how far along I am. Got results to that a week later. They told me it was negative. I have since taken 3 more tests, including one that estimates how far along u are, and it said 3+ weeks which was as high as it goes. I have been having extreme nausea and fatigue and no bleeding. The urgent care assures me that im not pregnant. What should I do? I just want to know for sure either way.

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

    You should probably go see your primary care doctor and have them do another blood test. If that comes back negative you will need to ask the doctor why you keep getting positive pregnancy tests when the blood test is negative.

  • feeling lost

    I have taken about 8 home pregnancy test all with the results of positive but went to the dr today for a blood test and it came back negative.. I haven’t had a period since june 30th and have been having pregnancy symptons.. i would be 6 weeks along could the blood test be wrong?

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

    There’s always a possibility that the lab made a mistake. If you wait a week and take get another positive pregnancy test, I’d say another visit to the doctor is in order for another blood test.

  • Jennifer Salvador

    i noticed that the clinic i did a blood test for pregnancy used the same kit i am using for my urine pregnancy test, was this right?

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

    Usually the doctor’s office sends the tests out for analysis so I don’t know. If they were able to give you results, maybe the test looked the similar but was specifically made for detecting pregnancy using a blood sample.


Last modified: June 3, 2014