Beta HCG Blood Test
Beta HCG Blood Test, A quantitative human chorionic gonadotropin (HCG) test measures the specific level of HCG in the blood. HCG is a hormone produced in the body during pregnancy.
Other HCG tests include:
After you conceive (when the sperm fertilizes the egg), the developing placenta begins to produce and release hCG. It takes about 2 weeks for your hCG levels to be high enough to be detected in your urine using a home pregnancy test.
A positive home test result is almost certainly correct, but a negative result is less reliable. If you do a pregnancy test on the first day after your missed period, and it’s negative, wait about a week. If you still think you might be pregnant, do the test again or see your doctor.
Why was the hCG blood test performed?
The hCG blood test is performed to:
- confirm pregnancy
- determine the approximate age of the fetus
- diagnose an abnormal pregnancy, such as an ectopic pregnancy
- diagnose a potential miscarriage
- screen for Down Syndrome
The hCG blood test is sometimes used to screen for pregnancy before you undergo certain medical treatments that could potentially harm a developing baby. If an hCG test concludes that someone is pregnant, healthcare professionals can ensure that they’re protected and that the fetus isn’t harmed by those medical treatments.
How the Test is Performed:
A blood sample is needed. This is most often taken from a vein. The procedure is called venipuncture.
How to Prepare for the Test:
No special preparation is needed.
Why the Test is Performed:
HCG appears in the blood and urine of pregnant women as early as 10 days after conception. Quantitative HCG measurement helps determine the exact age of the fetus. It can also assist in the diagnosis of abnormal pregnancies, such as ectopic pregnancies, molar pregnancies, and possible miscarriages. It is also used as part of a screening test for Down syndrome.
hCG blood levels by week:
Low levels of hCG may be detected in your blood around 8 to 11 days after conception. hCG levels are highest towards the end of the first trimester, then gradually decline over the rest of your pregnancy.
The average levels of hCG in a pregnant woman’s blood are:
- 3 weeks: 6 – 70 IU/L
- 4 weeks: 10 – 750 IU/L
- 5 weeks: 200 – 7,100 IU/L
- 6 weeks: 160 – 32,000 IU/L
- 7 weeks: 3,700 – 160,000 IU/L
- 8 weeks: 32,000 – 150,000 IU/L
- 9 weeks: 64,000 – 150,000 IU/L
- 10 weeks: 47,000 – 190,000 IU/L
- 12 weeks: 28,000 – 210,000 IU/L
- 14 weeks: 14,000 – 63,000 IU/L
- 15 weeks: 12,000 – 71,000 IU/L
- 16 weeks: 9,000 – 56,000 IU/L
- 16 – 29 weeks (second trimester): 1,400 – 53,000 IUL
- 29 – 41 weeks (third trimester): 940 – 60,000 IU/L
The amount of hCG in your blood can give some information about your pregnancy and the health of your baby.
- Higher than expected levels: you may have multiple pregnancies (for example, twin and Tripler) or abnormal growth in the uterus
- Your hCG levels are falling: you may be having a loss of pregnancy (miscarriage) or risk of miscarriage
- Levels that are rising more slowly than expected: you may have an ectopic pregnancy where the fertilized egg implants in the fallopian tube
Are there reasons besides pregnancy for hCG testing?
Beta hCG is considered a tumor marker, which means it’s a substance that’s excreted by some kinds of tumors. That’s why, in some cases, the hCG blood test may also be used to evaluate and manage certain types of cancer.
Cancers that can cause higher-than-normal hCG levels include:
Noncancerous conditions, such as cirrhosis, ulcers, and inflammatory bowel disease (IBD), can also result in hCG levels being elevated.
Although hCG is closely associated with pregnant women, the hormone can also be present in men. An hCG blood test can indicate that a man has testicular cancer. If a man detects a lump in one of his testicles, or if a doctor suspects that he’s at risk for testicular cancer, the test can be used to see if hCG is present.
If hCG is present in a man’s blood, further testing will be needed to determine the cause.
If an hCG test comes back negative, that generally means you’re not pregnant.
However, if the test was performed too early in the pregnancy before your body has had time to produce enough hCG, you can get a false negative. If there’s a false-negative test result, the test indicates that a woman isn’t pregnant, when in fact she is.
Because hCG levels change so quickly during early pregnancy, the hCG blood test should be repeated within 48 to 72 hours to observe how the hormone level is changing.
On the other hand, hCG can be present in some nonpregnant conditions, potentially causing a false-positive hCG pregnancy test.
If there’s a false-positive test result, the test indicates that a woman is pregnant, when in fact she isn’t. It’s also possible to get a false-positive result if your body produces certain types of antibodies that have fragments of the hCG molecule, or if there were errors in the lab. If there’s any doubt about the results, a different testing method can be used to confirm.
Risks of having blood drawn are slight, but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Blood accumulating under the skin (hematoma)
- Infection (a slight risk any time the skin is broken)