Alternative Names pregnancy test, urine, urine pregnancy testing, HCG qualitative urine test, human chorionic gonadotropin, urine HCG, qualitative urine beta-HCG
Definition This test detects the level in the urine of the pregnancy hormone known as human chorionic gonadotropin (HCG).
Who is a candidate for the test? HCG is a hormone that is produced by the placenta. It is detectable in the blood and urine within 10 days after fertilisation. After implantation of the fertilised egg, the levels of HCG rise rapidly in the first trimester and reach a peak 60 to 80 days after implantation. HCG is thought to be important in converting the normal corpus luteum into the corpus luteum of pregnancy. The corpus luteum is a hormone-secreting structure that grows on the surface of the ovary after ovulation takes place. In pregnancy, functions of the corpus luteum include:
promoting the growth of the foetus through the 12th week of pregnancy.
stimulating the development of foetal sex organs.
promoting the synthesis of male hormones by the foetal testes.
Because HCG is produced by the placenta, it is an indicator of pregnancy. HCG is produced regardless of whether implantation of the egg occurs within the uterus or outside of the uterus.
Most commonly, this test is performed to confirm or rule out pregnancy. Women of childbearing age who have not been using birth control while having intercourse should be screened with a quantitative HCG test if they are having the following symptoms:
delayed menstrual period.
breast tenderness.
pelvic pain.
irregular spotting or bleeding.
nausea or vomiting.
How is the test performed? The person supplies a urine sample. Ideally, this is from the first urination of the morning. This urine tends to be highly concentrated. The sample may be sent to the laboratory and analysed for the presence of HCG. However, most doctors will perform this test in the surgery.The hormone is measured in terms of quantity per cubic centimetre of urine. The hormone is detected with a test that uses specialised antibodies. These substances clot with the HCG molecules. When this happens, the test is deemed positive. It is this reaction that makes the test strip turn colour in over-the-counter pregnancy tests.
What is involved in preparation for the test? No special preparation is necessary for this test.
What do the test results mean? Abnormal test results may indicate:
threatened or spontaneous abortion, or miscarriage.
Other potential diagnoses that may mimic pregnancy but have negative HCG results include:
ovarian cysts.
bleeding without ovulation.
dysfunctional uterine bleeding, which is abnormal bleeding from the uterus that occurs outside of the normal menstrual flow.
pelvic inflammatory disease (PID), which is widespread infection of the ovaries, tubes, and other reproductive organs.
polycystic ovary disease, which is an endocrine disorder causing multiple cysts on the ovaries.
ovarian cancer.
menopause.
Author: Eva Martin, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 26/05/2005 Contributors Potential conflict of interest information for reviewers available on request
