What Does the Blood Pregnancy Test Reveal?
A blood pregnancy test is run by the obstetrician during the first office visit, in most cases. While the urine pregnancy test can detect the presence of the hCG hormone, it cannot tell the doctor how much of the hormone is present in the body. The blood pregnancy test delivers an hCG level which can tell a lot about the baby, or babies.
Human chorionic gonadotropin, or hCG, releases into the body starting from the first moments after conception. This hormone is first released by the embryo with the placenta taking over production soon after. Progesterone levels needed for the growth of the fetus are protected by hCG. Blood tests taken after the 4th week of a pregnancy should measure hCG levels between 5 and 426 mlU/ml. This number will grow exponentially until the 10th week of pregnancy when the levels will peak. If the hCG levels are far greater, the blood pregnancy test could have revealed something else.
In a multiples pregnancy, the hCG level will often be higher than with a single pregnancy, in some cases. The embryo is responsible for releasing the hCG before the placenta takes over. This means if there are multiple fetuses, more hCG could be released. The blood pregnancy test may come back with these higher than normal levels leading to an early ultrasound to rule out a multiple pregnancy.
The higher than average hCG level could also be indicative of an ectopic or molar pregnancy. If the ultrasound does not reveal a fetus in the uterus, the mother will have to undergo further testing to find the source of the hCG. The ectopic pregnancy will not end in a live birth. A molar pregnancy is a pregnancy that occurs without an egg nucleus. This pregnancy will cause very elevated hCG levels and a larger than gestational age growth of the abdomen.
Understanding Pregnancy Tests: Urine & Blood
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There are two types of pregnancy tests; one uses a urine sample, the other a sample of blood. Both tests detect the presence of a hormone called human chorionic gonadotropin (hCG). This hormone is produced by the placenta shortly after the embryo attaches to the uterine lining and builds up rapidly in your body in the first few days of pregnancy.
It is this rapid shift in hormones that triggers most of your pregnancy symptoms.
Urine tests can be performed in two different ways and these can be performed at home or in a clinic. One way involves collecting your urine in a cup and dipping a stick into the urine or putting urine into a special container with an eyedropper. Another option involves placing a stick into your urine stream and catching your urine in midstream.
Tests vary in how long you have to wait to get a result. You will be looking for a change in color, a line, or a symbol (like a plus or minus). The newer digital pregnancy test offered by Clearblue Easy makes reading your results simple: the window will either show the words “not pregnant” or “pregnant”.
You can also get recommended midstream urine tests online:
All tests come with instructions, and it is important that you follow these instructions to get an accurate reading. View a video demonstration of how a pregnancy test works.
When can I take a urine test?
Most doctors recommend that you wait until the first day of your missed period before taking a urine pregnancy test. This is usually about two weeks after conception. However, some tests are more sensitive than others and can be taken earlier.
How accurate are urine tests?
Urine tests or home pregnancy tests are around 97% accurate when done correctly. Home pregnancy tests are great to use because they can be done at home, they are usually low in cost (anywhere from $7.99 to $19.99), private, they give a fast result, and are easy to use.
However, if done incorrectly or taken too early, the result can be inaccurate. If you get a negative result and still have symptoms of pregnancy (missed period, nausea, breast tenderness and fatigue), wait a week and take another test or contact your doctor so you can have a blood test done.
There are two types of blood tests. A quantitative blood test measures the exact amount of hCG in the blood, and a qualitative hCG blood test gives a simple yes or no answer to whether you are pregnant or not.
Advantages of having a blood test done:
- Can detect a pregnancy earlier than a urine test at about 7-12 days from possible conception (but if a negative result is received, a test should be repeated if a period is missed.)
- Can measure the concentration of hCG hormone in your blood (this is useful information for your healthcare provider in tracking certain problems in pregnancy)
Disadvantages to having a blood test done:
- More expensive than a urine test (price depends on cost of doctor’s visit and lab fees)
- Takes longer to get result
- Must be done in a doctor’s office
Frequently Asked Questions About Pregnancy Tests
If I get a positive result on a home pregnancy test, does that mean I am pregnant?
A positive result from a home pregnancy test shows the presence of the hormone hCG in your system. When an egg is implanted in a woman’s uterine lining, hCG hormones begin to develop and multiply. This is a sign that you have become pregnant.
If I get a negative result on a home pregnancy test, does that mean I am not pregnant?
A negative result can mean that you are not pregnant, you took the test too early, or you took the test wrong. Pregnancy tests vary in their sensitivity (how soon they can detect the hormone hCG), and you may not have given your body enough time to produce enough hCG hormones that will show up on the test.
Also, if you let a test sit for too long (after the instructions on the box tell you), the test is invalid. It is best to follow the instructions and wait until you have missed a period before taking the test. Most pregnancy tests come with two in a box, and it is a good idea to take both.
When is the earliest that I can take a home pregnancy test?
It is recommended that you wait until you have missed a period to take a home test. A missed period is often one of the first signs of pregnancy. If you cannot wait that long to find out and you know the day you may have conceived, then the earliest you can take a test would be 14 days from possible conception.
What if I take a couple of home pregnancy tests and get different answers?
If you have received different answers on multiple pregnancy tests, it is recommended that you get a blood test done to get an accurate answer.
Last updated: March 4, 2017 at 19:25 pm
Compiled using information from the following sources:
1. MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); Prenatal Testing.
Should You Get a Pregnancy Blood Test?
Wondering whether to trust an at-home pregnancy test or head to the doctor for a blood draw? Here’s what you need to know if you’re trying to confirm that you’re pregnant.
By Elena Donovan Mauer
When it comes to choosing between a urine test — the kind of at-home pregnancy test you can easily find at your local drugstore — and a pregnancy blood test, the biggest difference is sensitivity. Although a home pregnancy test can usually pick up a concentration of about 50 units of hCG (the pregnancy hormone human chorionic gonadotropin), a pregnancy blood test can detect as little as 5 units of hCG, explains Daniel Roshan, M.D., ob-gyn at Rosh Maternal-Fetal Medicine in New York City.
That sensitivity can make a big difference if you want or need to know whether or not you’re pregnant very early, Dr. Roshan says. “If you do a pregnancy test before you miss your period, the result may be negative with a urine test but positive with a blood test.”
How Accurate are Pregnancy Tests?
Early pregnancy tests aren’t usually necessary, but they can make a difference for women at higher risk for miscarriage or ectopic pregnancy. Ectopic pregnancy, also known as tubal pregnancy, occurs when the fertilized egg remains in the fallopian tubes, instead of in the uterus, where it should be. “A patient would go to the doctor right away if they had a previous miscarriage so the doctor can check their blood and [she] can have a sonogram to look inside and see that everything is okay and it’s a healthy pregnancy,” says Dr. Roshan.
For most women, a pregnancy blood test isn’t necessary. If you’ve taken a home pregnancy test and gotten a positive result, your ob-gyn will likely see you around eight weeks after your last menstrual period and confirm your pregnancy with a transvaginal ultrasound. Sometimes, however, a doctor can’t detect the pregnancy on an ultrasound right away, and in that case she may order a blood pregnancy test, says Cristina Perez, M.D., an ob-gyn at the Women’s Specialists of Houston at Texas Children’s Pavilion for Women.
The blood test will consist of at least two blood draws, about 48 hours apart. Early in pregnancy, your hCG levels should double approximately every 48 hours. By seeing the change in hCG levels, the doctor can evaluate for a miscarriage or ectopic pregnancy, or confirm that your pregnancy is progressing healthily.
Are You Pregnant? How to Know for Sure
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When should I request a blood pregnancy test?
A blood pregnancy test is also referred to as a pregnancy serum test. It is used to detect pregnancy by measuring the amount of pregnancy hormone in the bloodstream. The pregnancy hormone is known as human chorionic gonadotropin or hCG. This hormone can be detected in the urine and bloodstream within a period of ten days after fertilization has occurred and is produced by the placenta. Blood pregnancy tests are of two types, a quantitative blood test which detects the exact quantity of the pregnancy hormone in the woman's bloodstream and a qualitative blood test which provides a yes or no answer to if the woman is pregnant.
Blood pregnancy tests are able to detect pregnancy even before a home pregnancy test. Detection through these tests is possible 7 to 12 days from the date of possible conception. They can also measure the amount of pregnancy hormone in the blood. This information is useful when certain problems related to pregnancy are being tracked by your doctor. If a woman is experiencing symptoms such as a delayed period, pain in the pelvic area, tenderness in the breasts, vomiting and spotting, a blood pregnancy test may be done to confirm if she is pregnant or not.
A normal pattern of human chorionic gonadotropin levels over a period of time is characteristic of a healthy pregnancy. The level of pregnancy hormone tends to rise during the first trimester of pregnancy and then slowly starts to decrease. In the first trimester, the blood pregnancy test may be done again and again to check if the hormone levels are rising normally. If this does not happen, there may be trouble with the pregnancy. After childbirth, the levels fall back to zero very quickly. This level will also decrease if miscarriage or abortion has taken place. Blood pregnancy tests are more accurate that home pregnancy tests. However, the results also largely depend on the laboratory and the method of performing the test. In some cases, the home pregnancy test may be positive, while the blood pregnancy test may turn out negative. This is because laboratories differ as to what constitutes a positive pregnancy test. Usually the cut off for positive results are 5, 10 and 25 units. Levels that fall before 5 are considered negative. In many cases false positive home pregnancy test results may also occur. Diuretic medications may sometimes interfere with the results of a qualitative blood pregnancy test. Therefore if a woman is taking such medication, she may obtain negative results even though she may be pregnant.
Submitted by M T on March 5, 2010 at 02:04
A pregnancy test is done to determine if a woman is pregnant. Firstly the process of pregnancy should be understood. At the start conception occurs when the sperm meets the egg and fertilizes the egg. After the sperm meets the egg it travels through the fallopian tube down to the uterus. Once it reaches the uterus it tries to cling onto the walls of the uterus by trying to implant itself. Only once the fertilization occurs after implantation then only does pregnancy occur. A pregnancy test looks for any chemical markers or any hormones that are associated with pregnancy. These chemical markers are found in the blood and the urine samples. One reliable marker for pregnancy is the human chorionic gonadotropin or the hCG which can only be detected after the implantation. It is known to be a hormone that is secreted by the developing placenta shortly after a fertilized egg has been implanted in the uterus.
Human chorionic gonadotropin is detectable in urine and blood within just ten days of fertilization. There are two kinds of blood pregnancy test namely quantitative blood test which measures the exact amount of hCG in the blood and the qualitative blood test which simply determines if a woman is pregnant or not. A blood pregnancy test can detect pregnancy about 7to 12 days after conception. It also helps to measure the amount of hCG in the blood. This is helpful to a doctor as it helps in tracking certain problems in pregnancy. If there are any symptoms of pregnancy like missed or delayed menstrual cycle, breast tenderness, pelvic pain or nausea a blood pregnancy test can be done to determine pregnancy. A blood pregnancy test is considered more reliable than a home urine test. Blood test measure smaller amounts of the hCG hormone and therefore can detect pregnancy earlier than a urine test.
A blood pregnancy test or an hCG test is measured in thousandths of International Units, or mIU. If a woman is pregnant then at ten days after ovulation the amount of hCG in her system should be around 25 mIU. At 12 days past ovulation it should be around 50 mIU and around 100 mIU at around two weeks after ovulation. Blood tests can be used to determine pregnancy at around 5mIU but this at times can present a false positive. Blood tests can determine pregnancy earlier than home pregnancy tests. A doctor should always be consulted to determine results of a blood pregnancy test.
Submitted by M T on February 25, 2010 at 01:09