Human Chorionic Gonadotropin (HCG)
In some cases a combination of screening tests is done in the first
trimester to look for Down syndrome. This screening
test uses an ultrasound measurement of the thickness of the skin at the back of
the fetus's neck (nuchal translucency), plus a blood test of the levels of the
pregnancy hormone hCG and a protein called pregnancy-associated plasma protein
A (PAPP-A). This test is about as accurate as the second-trimester maternal
serum quad screening.1
HCG urine tests
HCG urine tests are usually used
for routine pregnancy testing. The test does not measure the exact amount of
hCG, but it shows if hCG is present. Home pregnancy tests that show hCG in
urine are also widely available.
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Pregnancy: Should I Have Screening Tests for Birth Defects?
Why It Is Done
A test for human chorionic gonadotropin
(hCG) is done to:
- See whether you are pregnant.
an ectopic pregnancy.
- Find and check the treatment of a molar
- See whether there is an increased chance of birth defects such as
Down syndrome. The test is used in combination with other screening
- Find and check the treatment of a cancer that develops from
an egg or sperm (germ cell cancer), such as cancer of the
ovaries or testicles. In such cases, a test for
alpha-fetoprotein may be done along with a test for hCG.
How To Prepare
If a blood sample is collected, you do
not need to do anything before you have this test.
If a urine test
is done, the first urine of the day is generally the best to use because it has
the highest level of hCG. A urine sample collected at least 4 hours after
the last urination will also have high amounts of hCG.
How It Is Done
Human chorionic gonadotropin (hCG) may
be measured in a sample of blood or urine.
Blood sample collection
The health professional
drawing blood will:
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
- Put the needle into the vein. If the needle is not placed
correctly or if the vein collapses, more than one needle stick may be
- Attach a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure to the site and then a
If possible, collect a sample
from the first urine of the day (this urine generally has the highest level of
hCG). A urine sample collected at least 4 hours after the last urination
will also have high amounts of hCG.
- Place the collection container into the
stream of urine, and collect about
4 Tbsp (60 mL) of
- Do not touch the rim of the container to your genital area,
and do not get toilet paper, pubic hair, stool (feces), blood, or other foreign
matter in the urine sample.
- Finish urinating into the toilet or
- Carefully replace the lid on the container, and return it to
the lab. If you are collecting the urine at home and cannot get it to the lab
in an hour, refrigerate it.