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Are home pregnancy tests accurate ?
What is a home pregnancy tests ?
A home pregnancy tests measures the presence of the hormone human chorionic
gonadotrophin (hCG) in your urine. This hormone is first secreted at the
time the fertilised egg implants in the uterus (about six days after
fertilisation) by the cells which go on to form the placenta. Levels of
the hormone build up rapidly in your body in the first few days following
implantation. Usually, home-pregnancy tests should be able to pick up the
hCG in your urine by the first day you miss your period. Levels of hCG
peak between the 60th and 90th days of pregnancy.
If you have a negative result when you first test, it may be that the
levels of hCG have not yet reached a level where they can be detected by a
tests, even by the day your period is due, so you may want to wait a few
days then test again.
Not all pregnancy tests are the same. Some are more sensitive and usually
more expensive as a result. The more sensitive tests can detect pregnancy
even if you have only a small amount of hCG in your system. Concentrations
of hCG are reported in milliInternational Units (mIU) or amounts equal to
1/1000th of an IU per millilitre. A test with a sensitivity of 20 IU/L is
more sensitive than one with 50 IU/L. You should be able to find this
information on any pregnancy test box.
How to do a home pregnancy test.
For most home pregnancy test, you either hold a test strip in your urine
stream as you urinate into the toilet or you collect your urine in a clean
cup and dip your test strip into the cup. If you are pregnant, most test
strips produce a colored line, but this will depend on the brand you
purchased. Read directions carefully to interpret the results. Read the
instructions for the test you bought and follow them carefully. Make sure
you know how to get good results. The test usually takes only a few
minutes.
Some tests are able to detect low levels of hCG, indicating pregnancy. For
the most reliable results, test 1-2 weeks after you miss your period.
There are some tests for sale that are sensitive enough to show you are
pregnant before you miss your period.
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You can improve your chances for an
accurate result by using your first morning urine for the test. This urine
has accumulated in your bladder overnight. If you are pregnant, it will
have more hCG in it than urine collected later in the day.
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If you think you are pregnant, but your
first test was negative, you can take the test again after several days.
Because 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.
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The home pregnancy test and the urine
pregnancy test used by your health care provider are similar. Both can
detect hCG, but your provider is probably more experienced in running the
test. The doctor may follow up with a more sensitive blood test to see if
you are pregnant and may conduct a physical exam for a more reliable
result.
How do I interpret the results ?
1. Look at the regions marked 'C' and 'T'
on the test card. 'C' indicates a control. This band must always appear
because this is the comparison band. 'T' indicates the test sample.
2. If only one pink/purple band appear, in the region marked 'C', it means
that the test is negative for pregnancy.
3. If two pink/purple bands appear, one in the region marked 'C' and the
other in the region marked 'T', it means that the test is positive for
pregnancy
4. In case no bands appear, then the test is invalid. Repeat the test with
a new pack of pregcolor cards after 72 hours.
5. If the line formed in region 'T' is faint, this could be due to low
levels of hCG
hormone. In case of a faint band, repeat the test with a new pack of
pregcolor cards after 72 hours.
Are home pregnancy test accurate ?
If you follow directions to the letter, home pregnancy tests are 97%
accurate. But mistakes do happen, which is why some kits come with two
tests. There are several reasons why a home pregnancy tests may be
negative: you may not be pregnant, or your body may not be making a normal
amount of hCG. If you test too early (before the first day of your missed
period), you may get a false negative result because not enough of the
hormone has built up in your system. If the tests comes back negative but
you still suspect you're pregnant, wait a few
days, read the directions carefully, and try again. False positives, when
the tests says you're pregnant but you're not, are rare.
If you have irregular periods, it may be harder to calculate when your
period is due. Allow for your longest cycle in recent months before
testing. If you have recently stopped taking the contraceptive pill, you
may not know how long your natural cycle is so you may end up testing
either too soon or too late. If your tests is negative in either of these
situations, you should test again in three days.
How are home pregnancy tests different from
ones performed by doctors ?
Many clinics use home pregnancy tests to verify pregnancies, in which
case, they're exactly the same. Occasionally, women are given blood tests,
but they aren't all that different from home pregnancy tests, either. Both
types look for hCG in your body. A blood tests is much more sensitive than
any over-the-counter kit, which means it can determine whether you're
pregnant just six to eight days after you ovulate.
False Negative Or False Positive Test Result
Pay attention because this can get confusing. A false negative means
that the pregnancy test indicated the test was negative (you aren’t
pregnant), but, in fact, it isn’t really negative,it’s really positive
(you are pregnant). A false positive is the reverse (totally confusing,
I know).
Any test that you can do on yourself has a false positive and a false
negative rate. The manufacturers try to design a test to pick up the
entire spectrum of possibilities from everyone who is normal to those
who are abnormal. Unfortunately, making any test sensitive to everyone
is impossible. For example, if you lower the test to pick up an
abnormality, you may pick up a lot of false positives. When you design a
test to rule out a problem (for example, you want it to come back
negative in most instances), you will have a few false positives.
Scientists try to minimize these instances, but they can’t ever
eliminate them, so they use a bell-shaped curve.
The upshot of this information for you is that if you know you’re
pregnant because your body is telling you something that the test
doesn’t, then repeat the test. Eventually, it should turn out positive;
or preferably, have your doctor do the test. It’s rare that the doctor
will have a problem with the test, but it is possible..
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