The basis of the test work for pregnancy - a reaction that reveals the hormone hCG (human chorionic gonadotropin).He begins to produce a woman's body a week after fertilization, after implantation, or attachment of a fertilized egg to the uterine wall.Before implantation of hCG in the body is not, so it is impossible to determine whether the pregnancy.
Types of tests
All pregnancy tests are divided into three groups.
- test strips.The operating principle of this test is as follows.In a clean glass container should collect morning urine as it contains the highest concentration of hCG hormone.Further dipped into the urine test strip.there is a control strip, and if it appears next to the other on the surface of the dough - a positive pregnancy test.
This analysis method is not very reliable, because the light can not sufficiently impregnated with urine, and the result will be incorrect.Alternatively, if the test strip is lowered deeper than necessary or to hold urine longer than necessary, the error will be required.It is also possible in the manufacture of marriage, when the test strip impregnated with a reagent bad, for example.That is why these items are quite cheap.For the screening test procedure should be repeated after 48 hours.
- Tablet tests.They are also more expensive previous, and more reliable.These tests are used in hospitals for analysis.His body has two windows, the first of which is applied a drop of urine, and the second after a while result appears.In this case, a positive pregnancy test - is the acquisition of a colorless color reagent.
- jet test.Today it is - the most reliable copy of the pregnancy.This kind of test case contains a special layer of particles that interact with the hormone HCG, provided its presence in the urine of a woman, that is, in the case of pregnancy.Unlike other kinds of dough, this is inserted under the stream of urine, and does not fall into the tank, so it is quite suitable for use in all conditions and at different times of the day.The result will be ready in a minute after the procedure, and quite reliable.But this test and accordingly high price as compared with others.
There is also a test system with integrated reservoir for urine, with a window for the result.The amount of urine in the container does not affect the analysis result, as the system will absorb the necessary amount for the test.After a short while, in the window will show the result.
Sometimes the test may give erroneous results.Maybe test system stored properly, or when the meeting was not followed instructions.The error will be in the case of the test at a very early stage after fertilization, as in the blood and urine of women is very low concentration of hCG hormone.
Sometimes, very rarely, the content of hCG increases in connection with the development of neoplastic processes in the organs of the reproductive system.In this case, the test is positive, although the pregnancy has not occurred.
Compliance with instructions - a guarantee that the test result will be the most reliable.The test strip in any case can not substitute for urine stream, it is not designed for this purpose.The results should be assessed only after a few minutes, but do not overdo it (fifteen minutes or more on the test strip weak double strip may also occur, which does not mean anything).Reliable results can be obtained within five to seven minutes, no more.Prior to the reaction zone can not touch his hands, and you need to protect it from dirt and moisture.If the test has expired - you need to throw it away safely, he was unfit.
false negative result may be the case, if not all test conditions, and he was overdue been met, or if the period of pregnancy is too small.It is better to wait a week and repeat the test again.
false positive pregnancy test is if the woman takes drugs that contain hCG.After receiving these medications must be at least 14 days, otherwise the test will be flawed.Or, if high blood levels of other hormones, is very similar to hCG test will also be a false positive on the structure.This may be after menopause.
In addition, if the pregnancy was aborted, then for two or three weeks, the test can also be kept positive.Thus, under certain conditions, can be both a positive test in the absence of pregnancy, and negative if it is available.
Could there be a positive test during an ectopic pregnancy?Since the test is responsive to the appearance of the hormone produced by the female organism, regardless of the location of the fetus (or in the uterus in the pipe), the result may of course be positive.But whether the ectopic pregnancy or not - will be able to identify only a doctor.