Every young couple has a box of home pregnancy tests in the back of a bathroom cupboard. It’s the first step on the road that takes you from wondering if your period is just late, to the panic and excitement of pregnancy. And all you have to do is pee on a stick.
When you first go to confirm a pregnancy, there may be a urine pregnancy test as well. Urine tests at a doctor’s office seem like they ought to be more accurate. However, home pregnancy tests are just as accurate as urine pregnancy tests at the doctor’s office.
It might be natural to wonder why they aren’t more accurate. Also, if that’s the case, why bother with them? It all has to do with the type of tests and how they are used.
How Sensitive Are Doctors’ Urine Pregnancy Tests?
The accuracy rate for urine pregnancy tests, either at home or at the doctor’s office, is about the same. Both have the same degree of accuracy, which manufacturers say is about 99%. This is due to how the test is being done and what it’s looking for, as well as common practices regarding pregnancy tests.
Pregnancy tests are sensitive to the presence of a hormone called human chorionic gonadotropin, or more often just hCG. The most likely reason for high levels of hCG is that an egg has just been fertilized. The hormone is made by cells that cluster around the fertilized egg and will eventually come to form the placenta.
Pregnancy tests that use urine can detect hCG about 10 days after an egg has been fertilized. Most home pregnancy test (HPT) makers say their products have a 99 percent accuracy rate. That is sort of true, though as is usually the case things are a little more complex.
For example, most pregnancy tests are going to be more accurate after you’ve missed your period. The production of hCG tends to ramp up at that point, peaking at about 6 months into the pregnancy. Other factors can affect the accuracy to a lesser extent.
Due to the way different types of pregnancy tests are used, the current accuracy rate is considered good enough. Understanding the different types of tests and their accuracy rate might help explain why that is.
Qualitative Pregnancy Tests
This test is pretty straightforward. It just tests for the presence of hCG. There has to be a minimum amount of hCG for the test to work correctly, which is why you have to wait for a few days before the test will be accurate.
However, once there is enough hCG passing through your system, then into your urine, the test result will be positive. If there isn’t enough hCG, then it will come back negative.
It’s also possible for a test to return positive for a few reasons, even if otherwise there isn’t any hCG in your system. That is called a false positive when it reads positive but you aren’t pregnant. This is very rare, though it can occasionally happen.
The opposite is also possible when the result is negative but you actually are pregnant. This can be more common. It is commonly caused by:
- Take a test too early, before your body has produced enough hCG
- Check the test results too soon
- Use diluted urine
HPTs also expire, so there might be a negative result if the test is too old.
Many health centers use the HPT since they’re inexpensive and pretty accurate. Also, if you test positive you most likely actually are pregnant. Urine tests are therefore useful, as they can quickly remove a lot of the doubt. If a patient isn’t fond of needles, they may also use a urine test rather than drawing blood.
While these tests are pretty accurate, a doctor will usually go on to order additional tests to confirm a pregnancy.
Quantitative Pregnancy Tests
These tests don’t just detect whether there is any hCG, but the results will also tell the doctor how much hCG there is. Quantitative tests require blood to be drawn and then tested in a lab. There are some quantitative urine tests, but they aren’t used very often.
There are a couple of advantages to quantitative tests. The first is that they are actually more accurate. The possibility of a false negative or false positive is pretty small.
Additionally, these tests can also usually give the doctor a good idea of how long you’ve been pregnant. This can help calculate the due date and monitor the baby’s development. Quantitative HCG blood levels are often used to confirm the pregnancy is progressing normally in the uterus because ectopic or tubal pregnancies have an abnormal increase, possibly decrease in those levels. Ectopic pregnancies are quite dangerous, so seeing a healthcare provider early in pregnancy is essential. Other reasons for abnormal increase or decrease in those levels could signify a miscarriage, too. A blood test, a quantitative pregnancy test, is usually one of two tests that clinically confirm a pregnancy.
Blood tests may also be looking for another hormone, pregnancy-associated plasma protein-A, which is a marker for Down’s syndrome. Most likely you’ll also be tested for a variety of other things to assess your overall health.
Other Types of Pregnancy Tests
Urine tests and blood tests are two of the more common tests for confirming a pregnancy. In reality, most likely your doctor will have several tests performed before absolutely confirming a pregnancy. This may be true even if there isn’t a whole lot of doubt regarding the pregnancy.
Doctors look for a range of indicators for pregnancy, using both blood and urine tests, as well as physical examinations. That’s because all of these indicators can have more than one cause.
Pregnancy might be the most likely cause and the more indicators a woman has the more likely she is to be pregnant. However, doctors usually like to rule out other possibilities just to be on the safe side.
One of the most useful tools for confirming pregnancy is the ultrasound. It uses sound waves bouncing around in a woman’s body to create a picture of what’s going on inside. With it, it’s possible to ‘see’ the baby and monitor its health before it’s born. Ultrasound is often used in early pregnancy to confirm a pregnancy
The use of ultrasound so early and so often in pregnancy has led some to question its safety. In general, ultrasounds are considered very safe. Most studies have shown no adverse effects linked to using ultrasound. It is possible that using ultrasound may be linked to low birth weight. Follow-up studies have found that the difference is usually made up as the children grow, however.
Though it may come as a surprise, a home pregnancy test is just as accurate as a urine test at your doctor’s office. When used correctly, however, those tests are very accurate, accurate enough for many healthcare professionals to use them.
It wouldn’t be true to say that medical professionals rely on them, however. For pregnancy, as in a lot of situations, doctors like to have multiple ways of making sure they’re right. While a urine test is just as accurate at home as at the doctor’s office, that may be only one sort of test the doctor uses.
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