Why the test is performed
Beyond confirming a pregnancy, a B-hCG test can help a doctor:
Determine gestational age: Measure the fetus's age based on hormone levels.
Monitor pregnancy: Track the health and progress of a pregnancy, particularly during the first trimester, where hCG levels typically double every 48 to 72 hours.
Detect abnormalities: Help diagnose conditions like ectopic or molar pregnancy and risk of miscarriage, based on abnormal or slow-rising hCG levels.
Assess fertility treatment: Evaluate the success of treatments like in vitro fertilization (IVF).
Screen for birth defects: Use as part of prenatal screening for chromosomal abnormalities like Down syndrome.
Diagnose certain cancers: In rare cases, high hCG levels can indicate certain cancers, such as testicular or ovarian cancer.
Understanding the results
Test results are measured in milli-international units per milliliter (mIU/mL).
Negative: Levels below 5 mIU/mL typically mean a person is not pregnant.
Positive: Levels above 25 mIU/mL generally confirm a pregnancy.
Inconclusive: Levels between 6 and 24 mIU/mL are in a "gray area" and require repeat testing after a couple of days.
What abnormal results can mean
Lower-than-expected levels:
Miscarriage or blighted ovum (anembryonic pregnancy).
Ectopic pregnancy, where the fertilized egg implants outside the uterus.
Higher-than-expected levels:
Multiple pregnancies (twins, triplets).
Molar pregnancy, a rare condition involving abnormal tissue growth in the uterus.
Certain types of cancer.
How the test is done
A B-hCG blood test is a routine procedure with minimal risk.
A healthcare professional draws a small blood sample from a vein in your arm.
No special preparation, like fasting, is usually required, though you should inform your doctor about any medications you are taking.
The sample is sent to a laboratory for analysis.
Results are typically available within 24 to 48 hours.