Serum human beta chorion gonadotropic hormone (hCG) test – is the hormone that generates by Syncytiotrophoblast (multinucleated cells that found in the placenta of embryos) since fecundation day, and it’s quantity grows more and more in the blood and urine of pregnant woman.
The serum test to find Choriogoninum is the most sensitive and specific test. This test allows to find Choriogoninum at 8th-9th day of fecundation.
There are 2 kind of test: quantitative (the hormones quantity) and qualitative (showing if the hormone exists or no)
Pregnancy tests from urine are different in sensitive level and they are specific. Urine tests based on exposure of Choriogoninum parts in the female’s urine and consequently chorionic gonadotropin detection at 2-5 mIU/mL density. Urine test of pregnancy may give positive results at 20 mIU/mL hormone density level, which is equal to 2-3 days before menstruation cycle beginning. This kind of tests are very exact and available. It takes some 3 or 5 minutes to complete the test and all these tests work by the same principle which is to reveal beta-subunit of Choriogoninum via antibodies. False detection of pregnancy happens at so called Molar pregnancy (grape mole) or other pathology of placenta. Also in some cases the test of pregnancy could be positive after giving birth, miscarriage or abortion.
On the other hand we have false-negative output, that may happen at techniques breach of pregnancy test; or too much urine dilute; or when taking certain kind of medicine.
Other pregnancy test via urine use agglutination inhibition method. Such test demands, that a urine drop have mixed with antibodies to chorionic gonadotropin and the chorionic gonadotropin on latex basis. If result of the test is positive (pregnancy take place), the mix remains pure.
And the test result is negative when the parts of latex agglutinate (stick together).
This kind of test is more accurate after birth and abortion, because it is not so sensitive and it confirms the pregnancy failure with confidence.
Serum tests for pregnancy can be based on different principles. The ELISA test (stads for Enzyme-linked immunosorbent assay) is the most popular in laboratories. These tests determine the total amount of beta- Choriogoninum (CG). It runs by using homogeneous antibodies that connected with CG; the second antibody is adding to interact with CG and to cause color changing. Also ELISA test called Sandwich.
Some laboratories use radioimmunoassay technique (RIT). This test based on adding radio-marked anti-CG antibodies to the not marked CG in the blood pattern. Then they count the rest of not radio-marked pattern.
The level of CG doubles each 2 days in the beginning part of pregnancy. The number of Choriogoninum can rise up to 33%, which is normal for the pregnancy. The concentration of CG goes higher at 60-70 days of pregnancy, and after that again drop down to the lower number and it does not change after 100-130 days till the end of pregnancy.
