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hCG
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The Test Sample
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What is being tested?hCG is a protein produced in the placenta of a pregnant woman. A pregnancy test is a specific blood or urine test that can detect hCG and confirm pregnancy. This hormone can be detected 10 days after a missed menstrual period, the time period when the fertilized egg is implanted in the woman’s uterus. With some methods, hCG can be detected even earlier, at one week after conception.
During the early weeks of pregnancy, hCG is important in maintaining function of the corpus luteum . Production of hCG increases steadily during the first trimester (8–10 weeks), peaking around the 10th week after the last menstrual cycle. Levels then fall slowly during the remainder of the pregnancy. hCG is no longer detectable within a few weeks after delivery. hCG is also produced by some germ cell tumors and increased levels are seen in trophoblastic disease.
How is the sample collected for testing?hCG is commonly detected in urine. The preferred specimen is a random urine sample collected first thing in the morning. hCG can also be measured in blood drawn from a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed. However, do not drink large amounts of fluid before collecting a urine sample for a pregnancy test. This is because overly dilute urine may result in a false negative.
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This article was last reviewed on
February 9, 2008.
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