A pregnancy test measures a hormone called human chorionic gonadotropin (HCG). HCG is a hormone produced during pregnancy. It appears in the blood and urine of pregnant women as early as 10 days after conception.
How the test is performed: A pregnancy test may be performed using blood or urine. There are two types of blood pregnancy tests:
- Qualitative, which measures whether the HCG hormone is present
- Quantitative, which measures how much HCG is present
The blood test is done by drawing a single tube of blood and sending it to a laboratory. You may wait anywhere from a few hours to more than a day to get the results.
The urine HCG test is usually performed by placing a drop of urine on a prepared chemical strip. It generally takes 1 to 2 minutes for a result.
How to prepare for the test:
How the test will feel: The urine test involves normal urination into a cup. The serum tests involve drawing blood through a needle and into a tube. Any discomfort you might feel from the blood draw will only last a few seconds.
Why the test is performed: This test may be done to:
- Determine if you are pregnant
- Measure the age of the fetus (quantitative test only)
- Diagnose abnormal conditions that can raise HCG levels
Normal Values: HCG levels rise rapidly during the first trimester of pregnancy and then slightly decline.
What abnormal results mean: HCG levels should rise every 48 hours in the beginning of a pregnancy. HCG levels that do not rise appropriately may indicate a problem with your pregnancy. Some problems associated with an abnormally rising HCG level include miscarriage and ectopic (tubal) pregnancy .
Extremely high levels of HCG may suggest a molar pregnancy or more than one fetus -- for example, twins.
Your health care provider will understand the significance of your HCG levels, and he or she should discuss the levels with you.
Special considerations: Urine pregnancy tests will only be positive when you have sufficient HCG in your blood. If you are very early in your pregnancy, and the HCG level is below 25-50 mIU/mL, the test will be negative.
If you think you are pregnant, repeat the pregnancy test at home or at your health care provider's office.
