Pregnancy Test (hCG)

About the Test

Purpose of the test

The main use of a pregnancy test is to evaluate if you are pregnant. Both urine and blood tests for hCG can be used for this purpose, and repeat testing may be done to confirm a pregnancy. Very early in a pregnancy, tests that measure the amount of hCG may also help assess the age of a fetus.

Less often, hcG tests can be used to:

• Identify or rule out an ectopic pregnancy, when a fertilized egg attaches or implants in an abnormal area
• Check for pregnancy prior to surgery or other medical treatments
• Screen for Down syndrome if you are pregnant as part of prenatal screening
• Monitor a pregnancy that may be at risk of a miscarriage
• Help diagnose gestational trophoblastic disease (GTD), a term for pregnancy-related tumors

What does the test measure?

A pregnancy test measures a hormone in the body called hCG, which is created at higher levels during pregnancy. There are two different ways hCG results are reported:

• Qualitative: These hCG tests give a positive or negative result depending on the presence or absence of hCG in the sample. Qualitative tests can be done using either a blood or urine sample. This type of testing is done most often to confirm a pregnancy.
• Quantitative: This type of hCG testing measures the amount of hCG present in the blood. These tests frequently use a blood sample, but some urine tests can provide a degree of quantitative measurement. Along with confirming a pregnancy, quantitative hCG tests can also be used as part of the diagnostic process for abnormal pregnancies.

When should I get a pregnancy test?

A pregnancy test is most commonly done when you believe you may be pregnant. Testing may detect a pregnancy as soon as 10 days after conception. The accuracy of pregnancy tests usually increases if taken at least one to two weeks after a missed menstrual period.

It may also be done when there are signs and symptoms that suggest an ectopic pregnancy or a pregnancy that is failing.

Signs of an ectopic pregnancy may include:

• Abnormal vaginal bleeding
• Low back pain
• Pain in the lower abdomen or pelvic area
• Cramping on one side of the pelvis

Additional and more severe symptoms may develop if an ectopic pregnancy is not identified and treated, so it is important if you’re of childbearing age to talk with a doctor if you notice these symptoms.

Pregnancy testing may also be done as a routine test prior to some medical treatments, such as surgeries or chemotherapy, that could potentially harm a fetus.

A doctor can best determine if a pregnancy test is appropriate.

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