Can Blood Tests for Pregnancy be Wrong?

on Jan 05, 2013

by Maureen Stephens, BS, RN

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Can Blood Tests for Pregnancy Be Wrong?

Sometimes things do happen that cause a blood test to give inaccurate results. It is rare, but it does happen. Find out how.

Most people think that blood pregnancy tests are 100% accurate, all the time. While we know that blood pregnancy tests done at a doctor’s office are much more accurate and reliable than home pregnancy tests, can they ever be wrong? Experts say that blood pregnancy tests are as much as 99% accurate. Of course, that leaves room for a tiny bit of error. So, what can happen to make blood pregnancy tests turn out wrong? Read on to find out. Claim Your 20 Free Pregnancy Tests – Click Here

The test is performed too early

A blood pregnancy test can only detect hCG in the blood at around seven days post-conception. If a pregnancy test is done before that seven days is up, the test might not be able to detect the hCG yet. This can cause a negative result when a woman is really pregnant.

Too high hCG levels

Sometimes, a woman will have extremely high levels of hCG in her blood when she is not actually pregnant. This can lead to a false positive pregnancy test. Some of the reasons for high hCG levels can be a tumor, ovarian cancer, a multiple pregnancy, blood or protein in the urine, or certain medications.

Too low hCG levels

Sometimes a woman will have low or even negative hCG levels. There can be a few reasons for this. Some reasons for a low or negative hCG level can be an ectopic pregnancy, or even a miscarriage. Your doctor can help you determine the reason for low hCG levels.

Chemical pregnancy

Sometimes a woman can get a positive blood pregnancy test when she is not actually pregnant. This can sometimes be called a “chemical pregnancy“. A chemical pregnancy is basically a very early miscarriage. Most women do not even know they were pregnant when they have a chemical pregnancy. However, if a woman has a blood test done very near the time that she miscarried, she might have a positive test result when she is not really pregnant.

The bottom line

As you can see, sometimes things do happen that cause a blood test to give inaccurate results. It is rare, but it does happen. If you have a blood test and you are concerned about the accuracy of that test, just ask your doctor to perform another one to make sure.

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Can Blood Tests for Pregnancy be Wrong? , 3.0 out of 5 based on 2 ratings

Ms. Stephens has spent over twenty years in the healthcare world, specializing in obstretical and medical/surgical nursing. She joined ConceiveEasy as she has a strong interest in educating and empowering women and promoting fertility awareness.

Related posts:

  1. False Negative Pregnancy Tests
  2. Types of Pregnancy Tests
  3. Are Home Pregnancy Tests Accurate?
  4. Medications That Cause False Positive Pregnancy Tests
  5. Blood Tests for Infertility
  • Danyell84

    Wow, I always thought blood tests were very accurate always. Thanks for the info. I think I will stick with using my free Conceive Easy tests 2 weeks from a missed period.

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  • Zumba

    I had a blood pregnancy test and it came back negative but I have just been soo sick cant eat , cramps bloating , nausa and that metalic taste in my mouth I don’t know what to do ?

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  • Amy

    I’m so fustrated I have my period but they are very very barely there compare to my normal periods.I’ve had a 35 pound weight gain I am exhausted I am exhausted all the time I have pressure on my bladder I’ve had hair loss I am nauseous and my belly has gotten very extended and breasts are tender.I have had blood test be negativ.e. Please help me

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  • Brenda

    I am really confused.i had unprotected sex on August 24 i took the emergency pill almost 2 days after but before the 72 hour period! My last period was around aug 16 or 17th..but i have always had irregular menstruation so its impossible at this point to know whether its late or not..on friday september 13 i took 3 urine test all came out positive i went to the doctor yesterday got a blood preg test also positive…i an really confused could it be wrong did i take too early ??? Help please!

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  • Susie Hughes

    I have mirena iud in place. Have had no period now for over 6 weeks. Feeling very pregnant….. All symptoms! Have had blood test…. As I fear ectopic pregnancy…… Came back negative………then why do I feel so pregnant?

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  • Raquel Gutierrez

    i already had my son, but to find out about my pregnancy i went’nd got a blood test, my son was born a month early, premature, and a monrh earlier feom the due date i was told he would be born, but i just had to assure myself, can blood pregnancy test actually be inaccurate is that even possible?? ive always had irregular periods, but durimg the date they told me i was pregnant i had gotten my period, my pregnancy date was 7/7/12, expected due date 4/14/13.i got my periods in those months, june, july, n august, i never got my period in september though, so did they get it wrong im so confused!!!

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  • crystal brandon

    E I have a copper iud for 2yrs now since nov. 2013 i have been experiening pregnacy syptoms like i did with my last child. I have a bloated pregnacy belly again as if i were after i had completely lost it after i had give birth to my last child.i am constantly feeling baby like movements in my belly and also see my belly move. I seen obgyn and pregnacy test for both blood and urin has been negative. Also medical doctors do not detect me having a gi problem. I do not have gas and all else with me is well. So i really would like to know could be the problem especially with the moving inside of my belly its so uncomfortable and i am tired of testing. Would really like some help

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  • carol

    I had a baby 2 months ago n I haven’t got my period yet n I been having sex with protection I took 5 pregnancy test at home alredy n I’m not pregnant I also went with my gyn doctor n they took me another urine test n is negative n I never breastfeed my baby the only thing the doctor say is that I have very low iron and too much stress with 5 kidz that could be the reasons why I don’t get my period yet” n my question is do you recommend me too take a blood pregnancy test better ??

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  • Agador1114

    Another reason why ALL pregnancy tests can be wrong is if the women is experiencing a “Cryptic Pregnancy”. During a Cryptic Pregnancy the woman is in fact pregnant, but ALL of her tests, urine and blood are negative. I am currently 38 weeks pregnant and I have yet to have a positive urine OR blood test. I have created a Facebook page for women who are going through this. It is called “Cryptic Pregnancy Support Group”.

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  • Suzanne

    BLOOD PREGNANCY TESTS CAN BE WRONG!!! This is what is known as a “Cryptic Pregnancy”. Women who experience this NEVER get a positive test. I have created a support group for this on Facebook called “Cryptic Pregnancy Support Group”.

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  • winter_rogue

    I have done 5 home pregnancy tests done all positive , but my ultrasound they cant find a baby.. does it mean I am not pregnant?

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  • summer

    i missed my period last june, my last period was may 21-25. i toiok urine pregnancy test but the results are all negative. i tried blood test and its still negative. until now july 4 i doesnt have a period. do you think its still possible that i am pregnant?

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