Pregnancy test
Definition
A pregnancy test is a test of blood or urine used to determine whether a woman is pregnant.
See the following tests:
How the test is performed
The qualitative urine human chorionic gonadotropin (HCG) test is usually performed by placing a drop of urine on a prepared chemical strip. It usually takes one or two minutes for the strip to indicate the result.
The qualitative and quantitative serum tests are performed 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.
Quantitative tests are used to measure the level of HCG in your blood, which gives your doctor more information than the qualitative 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
Qualitative tests
Women who are late for their menstrual period (menses) often perform qualitative urine tests at home. Qualitative tests only indicate whether you are pregnant or not - yes or no. Home pregnancy tests are available at pharmacies and do not require prescriptions.
Sometimes the test will be performed at your doctor’s office before the first prenatal visit. This is done just to confirm the results of your home test. Doctors also perform a qualitative urine pregnancy test before performing a procedure or prescribing a medication that might adversely affect an existing pregnancy.
The qualitative urine test can detect HCG levels above 25-50 milli-international units per milliliter (mIU/mL). Serum tests can detect HCG levels above 5-10 mIU/mL.
Quantitative tests
Quantitative serum pregnancy testing is usually performed at a hospital or doctor’s office. This test measures the amount of HCG in your blood. It can measure amounts ranging from 5 mIU/mL to 2,000,000 mIU/mL or more.
Quantitative testing is performed when it is not sufficient merely to know whether you are pregnant or not. Sometimes, your doctor will need to correlate your HCG levels with the progress of your pregnancy.
Ask your doctor to explain the results of your quantitative pregnancy test.
Normal Values
In women who are not pregnant, both the qualitative urine and serum HCG tests will be negative. The quantitative HCG test will be less than 5 mIU/mL.
In a normal pregnancy, the HCG level should rise through the entire first trimester and slowly fall thereafter.
What abnormal results mean
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 twins.
Your health care provider will understand the significance of your HCG levels, and he or she should discuss the level’s significance with you.
What the risks are
There are no medical risks associated with testing for pregnancy.
Special considerations
Qualitative 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.
Therefore, if you are late for your period, you should wait 7 to 10 days before trying the test. If the test is negative, wait a few more days. If you still don’t menstruate, try the test again. If you still test negative and your periods do not return to normal, see your health care provider.
by Simon D. Mitin, M.D.
Medical Encyclopedia
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.