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Pregnancy test
Pregnancy test


Pregnancy test

Definition:

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.

See also:



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
  • Diagnose abnormal conditions that can raise HCG levels
  • Watch the development of the pregnancy during the first 3 months (quantitative test only)


Normal Values:

HCG levels rise rapidly during the first trimester of pregnancy and then slightly decline.



What abnormal results mean:

HCG levels should double 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.



References:

Webster RA. Reproductive function and pregnancy. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: Saunders Elsevier; 2006:chap 25.

Morrison LJ. General approach to the pregnancy patient. In: Marx J, ed. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 6th ed. St Philadelphia, Pa: Mosby Elsevier; 2006:chap 176.




Review Date: 10/28/2008
Reviewed By: Linda Vorvick, MD, Seattle Site Coordinator, Lecturer, Pathophysiology, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine; and Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Redmond, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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