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Doctor insights on: Medicines That Affect Blood Pregnancy Tests

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When are blood pregnancy tests accurate?

When are blood pregnancy tests accurate?

Pretty quick: The hormone betaHCG is detectable within 5-7 days of implantation. So it can be positve before a missed period. ...Read more

Dr. Abraham Jaskiel
4 Doctors shared insights

Pregnancy (Definition)

When your due date arrives, you will be more than ready to have your baby! Most women deliver the baby somewhere between 37 and 42 weeks. According to the American College of Obstetricians and Gynecologists, only 5% of babies arrive on the exact due date. Approximately 7% of babies are not delivered by 42 weeks, and when that happens, it is referred to ...Read more


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When are blood pregnancy tests definitely accurate?

When are blood pregnancy tests definitely accurate?

Yes: Serum measurement of HCG is very accurate in detecting pregnancy. Thanks for trusting HealthTap! ...Read more

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10 days late and had brown blood for a few days in the beginning of the month. Had negative pregnancy tests.

10 days late and had brown blood for a few days in the beginning of the month. Had negative pregnancy tests.

Uncertain: Reasons for missed / late period include: an anovulatory cycle in which no egg is released, marked v or ^ in weight; eating disorder; Over-exercising (endurance athletics), stress, travel, significant illnesses, oral contraceptives & other meds, Illegal drug use, breast feeding, hormone imbalances and medical problems (i.e., PCOS). Pregnancy is #1 reason. ...Read more

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Can be blood test -ve after having six +ve home pregnancy tests?

Can be blood test -ve after having six +ve home pregnancy tests?

Yes, but. . .: The pregnancy hormone, hcg, rises as the pregnancy grows, and falls if the pregnancy fails. So if you had a miscarriage, the pregnancy hormone level would drop. There is also such a thing as a "chemical pregnancy" which is a miscarriage that happens so early, that there is never any visible gestational sac by ultrasound. Lastly, you could have had a faulty batch of home pregnancy tests (unlikely). ...Read more

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What to do if I have six positive pregnancy tests and a negative blood test, could I be pregnant, or not?

What to do if I have six positive pregnancy tests and a negative blood test, could I be pregnant, or not?

Possible: Six positive tests are pretty darn convincing but the negative blood test could trump the urine tests. I would wait 10 days and repeat the blood test. Ask for both a qualitative result as well as a quantitative beta HCG ...Read more

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Is it possible to be 11 days late. Have negative blood and pregnancy tests at 10 days late and still be pregnant?

Is it possible to be 11 days late. Have negative blood and pregnancy tests at 10 days late and still be pregnant?

Yes: The method used when testing is important.
Early on the urine is best, but it must be the first urine of the day. There are things that can confuse the test. Be safe, behave as though you were pregnant and repeat the urine test on first voided urine in a few days if you don't get your period. I assume you are usually regular and not under lots of stress. ...Read more

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I took 2 pregnancy tests and 1 blood test they were negative! But I have all the pregnancy symptoms all of them he has came inside of me to.

I took 2 pregnancy tests and 1 blood test they were negative! But I have all the pregnancy symptoms all of them he has came inside of me to.

Not pregnant: If your urine pregnancy test and blood pregnancy tests are negative then you are not pregnant. That we know for sure. You'll have to investigate other causes for the symptoms you're having. ...Read more

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I have three positive pregnancy tests all different brands and none are expired. I had blood work done but it was negative. What should I do next!

False positives: The serum (blood) pregnancy test is definitive. One of the issues with urine tests is that if you let them dry for too long you will get an evaporation line (false positive). The other issue could be a very early miscarriage. If still not convinced ask for a second serum test be done. ...Read more

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I'm gonna rephrase my last question. Is it possible to have multiple negative pregnancy tests, including blood tests, throughout the whole pregnancy?

I'm gonna rephrase my last question. Is it possible to have multiple negative pregnancy tests, including blood tests, throughout the whole pregnancy?

Unlikely: Specially, blood test to detect beta-hcg to confirm viable pregnancy are very accurate. Plus ultrasound abdomen will give additional information which will be highly valuable in regards to pregnancy outcomes. ...Read more

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Why are blood pregnancy tests more accurate and detects sooner than urine tests?

Why are blood pregnancy tests more accurate and detects sooner than urine tests?

Because: Blood is more sensitive, blood detects down to 2-5 miu HCG urine can go down to about 25-30 miu and urine can be influenced by the concentration of the urine. ...Read more

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Are blood pregnancy tests accurate 2.5 months after intercourse?

Are blood pregnancy tests accurate 2.5 months after intercourse?

Yes: Serum measurement of HCG is very accurate in detecting pregnancy. Thanks for trusting HealthTap! ...Read more

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I have took 2 pregnancy tests one no second yes! Went to the hospital wasn't feeling to well and blood work said no. Can it to be to early.

I have took 2 pregnancy tests one no second yes! Went to the hospital wasn't feeling to well and blood work said no. Can it to be to early.

Early pregnancy: Due to the conflict of tests, it would be wise to follow up with another blood pregnancy test to assure that there are no mistakes. Occasionally, there may be a mistake with the urine test or the hospital lab could be at fault. ...Read more

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Two weeks late, two negative blood pregnancy tests. Usually get period every 30 days. What happened?

Two weeks late, two negative blood pregnancy tests. Usually get period every 30 days. What happened?

Irregular cycles: Irregular periods are one of the most common problems obgyns treat. If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. Infections ; hormonal changes can cause spotting. Your preg test is negative so you are not pregnant. There are many options available to help regulate the menstrual cycle. Schedule a visit. ...Read more

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I am showing signs that I am pregnant but all home pregnancy tests and blood test come back negative?

I am showing signs that I am pregnant but all home pregnancy tests and blood test come back negative?

Blood HCG test: If you had unprotected sex since your last period, missed your period by 5-7 days, did the test properly using first morning urine and it was negative, it is unlikely that you are pregnant. You may see your doctor for a blood HCG level that is more definitive. ...Read more

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3 positive urine pregnancy tests. Blood test at Dr's this am was negative. I'm still showing positive. What's going on?

3 positive urine pregnancy tests. Blood test at Dr's this am was negative. I'm still showing positive. What's going on?

Technique: Blood test is more sensitive than urine test. Please re-read the instructions for the test, including the time within which you read the lines. In general it takes two lines for a positive test. ...Read more

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I'm almost a week late, and pregnancy tests keep showing negative results? Is it too early? Or could I need a blood test?

I'm almost a week late, and pregnancy tests keep showing negative results? Is it too early? Or could I need a blood test?

Maybe: Pregnancy test are accurate about two weeks after conception. If it has been at least that long since your last unprotected sex, and you still don't get your period or a positive test using your first morning's urine, then you may want to ask your doctor for a blood test. Having said that, there are many reasons for a late period besides pregnancy: changes in weight, stress, travel, illness, etc. ...Read more

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I had a stubal litigation six years ago, did a few home pregnancy tests, 3 came out positive, when for blood tests showed negativ?

I had a stubal litigation six years ago, did a few home pregnancy tests, 3 came out positive, when for blood tests showed negativ?

False positive: Both urine and blood tests for pregnancy are accurate, but home tests are more subject to user error and quality of test. ...Read more

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I had 15 at home pregnancy tests come up positive. 15th one happened this morning. Went and got blood test today. Says neg? Confused! Help?

Rely on the blood: Home pregnancy test are not necessarily right all the time. I am not sure if you have a bad batch. I would also make sure that the blood test was a quantitative test with a number. I would also recommend to repeat the blood test one more time. ...Read more

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Aside from my question before I've taken multi home pregnancy tests n they've all come back indecisive/read error. So should I take a blood test?

Aside from my question before I've taken multi home pregnancy tests n they've all come back indecisive/read error. So should I take a blood test?

Yes: If hpt is not decisive and you missed a period after unprotected sex, it would be prudent to take a blood test.

If you do not wish to be pregnant, use contraception all the time, every time. You may consider implanted contraceptive, or IUD.
Practice safe sex.
Get HPV vaccine. ...Read more

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At 9 dpo I had a tiny streak of blood and then nothing since. I've taken early pregnancy tests and all negative. I'm 11dpo now. Was it too early to test?

At 9 dpo I had a tiny streak of blood and then nothing since. I've taken early pregnancy tests and all negative. I'm 11dpo now. Was it too early to test?

Yes, too early: Conception, as defined by the generation of a fertilized ovum, occurs within day or so of the sex. However, it takes about two weeks for the embryo to make enough HCG to produce a positive pregnancy test. Blood test may be done a day after a missed period. Home pregnancy tests should be done 4-5 days after the missed period. If the result is negative repeat the test in 4-5 days. Use first morning urine and follow instructions for the test carefully. ...Read more

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How is hCG measured in blood pregnancy tests? How is the level/number determined?

Antibody to HCG: Antibodies to the beta chain of HCG are used to measure HCG in blood and urine. Blood levels of 5 units or higher are usually indicative of pregnancy. ...Read more

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How accurate are blood pregnancy tests when you have a pituitary adenoma?

How accurate are blood pregnancy tests when you have a pituitary adenoma?

Very accurate: The pituitary adenoma will not decrease the accuracy of the blood pregnancy tests unless it is lh the adenoma is secreting, which is very rare. Most pituitary adenomas secrete prolactin, which will not interfere with a blood pregnancy test. ...Read more

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How accurate are blood pregnancy tests four weeks after unprotected intercourse?

Very accurate: Four weeks after the last intercourse, blood test would be positive if you were pregnant. At that stage you may also request an ultrasound examination, if there is any doubt. ...Read more

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Why am I testing positive to urine and blood pregnancy tests when I am not pregnant?

Why am I testing positive to urine and blood pregnancy tests when I am not pregnant?

Phantom hCG: Several posibilities:
1) you are really pregnant and test is right
2) phantom HCG you have antibodies in you that cross react with the test turning it positive
3) you are menopausal and your gonadotropins are so high they cross react with the test particularly if they are inexpensicve or the generic type
4) cancer, some of them make hcg
5) leftover placental tissue from previous pregnancy or sab. ...Read more

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I am 6 days late, pregnancy tests have been negative, had sex today and signs of little blood?

I am 6 days late, pregnancy tests have been negative, had sex today and signs of little blood?

Maybe: These symptoms might an early sign of pregnancy, but might also be due to an imbalance of hormones this cycle (a common normal occurance) ...Read more

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What is a reason for you to have 3 positive home pregnancy tests but a. Negative blood pregnancy test?

What is a reason for you to have 3 positive home pregnancy tests but a. Negative blood pregnancy test?

Possibilities: Here are a few possibilities:
1. You are doing the home test wrong --- letting it sit too long or have expired tests
2. You miscarried between doing a home test and taking the blood test
3. There is a lab error on your blood test.
Try repeating the urine now since you have had a neg blood test. If positive then repeat the blood. Blood is the more accurate test. ...Read more