The birth control pill introduces different hormones into your system. Learn how this may affect your menstrual cycle. Health Conditions Discover Plan Connect. Medically reviewed by Carolyn Kay, M. What is an hCG urine test? What are the uses of the hCG urine test?
Are there risks involved with this test? How do I prepare for the hCG urine test? How is the hCG urine test performed? What do the results of the hCG urine test mean?
Parenthood Pregnancy Getting Pregnant. Read this next. Early Pregnancy Symptoms. Medically reviewed by Debra Rose Wilson, Ph. Medically reviewed by Michael Weber, MD. A false negative pregnancy test is when you are pregnant but the test comes up negative.
The most common reason for a false negative is that you took the test too early. Even if your period is late according to your typical cycle, you might have ovulated later in the month. It's not uncommon to occasionally have an off or irregular cycle. Additionally, your count of when your last period occurred could be a few days off. No matter how sensitive the test, you won't get a positive home pregnancy test until enough days have passed since ovulation and conception and your body has had time to build up enough of the hormone the test detects.
If ovulation occurred later in the month, you will need to test later. There are many reasons you might ovulate later than you typically do. Pregnancy tests look for the pregnancy hormone hCG , which increases as a pregnancy progresses.
The normal range for hCG levels in pregnant people can vary widely. An early pregnancy test might pick up very low amounts of hCG. How much hCG you have isn't important; rather, it's how quickly your levels double and increase and this can only be measured with a blood test. Another common reason for getting a false negative is not having enough hCG in the urine you test.
In early pregnancy, you can dilute the hormone concentration in your urine if you drink a lot of water before testing. This is more likely to happen in very early pregnancy when you take the test later in the day.
A false negative can also occur due to test error. If you wait too long to read the results, you might get a false negative. That said, false positives are more common when reading a test too late. Make sure you that you follow the directions of the particular pregnancy test you purchased. To avoid confusion, be sure to read the result within the time window recommended. Another possible cause of a false negative is an expired test. Storing the test improperly for example, in a damp, hot bathroom cabinet can also cause it to malfunction.
A rare, counterintuitive cause for a false negative is that you are too far along in your pregnancy. For example, if your period is weeks to months late, a pregnancy test might come up negative. This is called the variant hook effect. In this case, a false negative pregnancy test can be caused by what is known as the high dose hook effect.
Ironically, unusually high levels of hCG can cause a pregnancy test to give a false negative result. A very rare cause of a false negative pregnancy test is when the hCG hormone in your body does not react with the anti-hCG chemicals in the test. In this case, you might need to wait a few more days before you can get a positive result or need to have a blood test.
You might ultimately need to have a serum pregnancy blood test or ultrasound to confirm pregnancy. If you still haven't gotten your period after a few more days, try the test again. If subsequent tests continue to show a negative pregnancy test result, you'll want to talk to your healthcare provider about further testing.
In rare cases, an ectopic pregnancy can cause a false-negative test result. An ectopic pregnancy is when the embryo implants somewhere other than the uterus.
This usually occurs in the fallopian tubes, but it can also happen elsewhere. An ectopic pregnancy does not develop properly and will not become a viable fetus. The formation of the placenta is delayed which impedes the production of hCG. Tests may not detect pregnancy until HCG has risen to a certain level.
This requirement means tests that detect lower levels of HCG may diagnose pregnancy earlier. Blood tests are typically more sensitive than urine tests. However, many home urine tests are highly sensitive. A analysis found that four types of home pregnancy tests were able to detect HCG levels up to 4 days before the expected period, or about 10 days after ovulation for many women. People must read the urine test instructions and follow them carefully.
Most tests use lines to show when a test is positive. The test line does not have to be as dark as the control line to be positive. Any line at all indicates the test is positive. Test strips can change color as they dry. Some people notice an evaporation line after several minutes. This is a very faint line that may look like a shadow. An individual must check the test within the time frame the instructions indicate, usually 3 minutes.
Tests read after 10 minutes may be inaccurate or show evaporation lines. Learn more about evaporation lines here. HCG tests are more likely to produce false negatives than false positives.
The longer after implantation a person waits to do the test, the more accurate it will be. HCG levels begin rising when an embryo implants in the uterus. Implantation usually happens a week or so after ovulation.
It can take several days for HCG levels to rise high enough for a test to detect the hormone. There are some tests for sale that are sensitive enough to show you are pregnant before you miss your period. You can improve your chances for an accurate result by using your first morning urine for the test. If you are pregnant, it will have more hCG in it than later urines. If you think you are pregnant, but your first test was negative, you can take the test again after several days.
Since the amount of hCG increases rapidly when you are pregnant, you may get a positive test on later days. Some test kits come with more than one test in them to allow you to repeat the test. Is this test similar to the one my doctor uses? The home pregnancy test and the test your doctor uses are similar in their abilities to detect hCG, however your doctor is probably more experienced in running the test. If you produce only a small amount of hCG, your doctor may not be able to detect it any better than you could.
Your doctor may also use a blood test to see if you are pregnant. Finally, your doctor may have more information about you from your history, physical exam, and other tests that may give a more reliable result.
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