How do pregnancy tests
The principle of action of such tests is based on the identification of a human chorionic gonadotropin in the urine of a pregnant hormone (HCG). After fertilization, the egg is divided into the embryo and the fetal shells. One of them (chorion) produces chorionic gonadotropin. With the further development of pregnancy, this hormone produces a placenta. Pregnancy tests use special reagents containing antibodies to hCG. In the urine women, chorionic gonadotropin is produced in a concentration available to detect the testing method - from about the second day following the delay in menstruation after conception. Specialized HCG blood test will reveal much faster conception - a few days after fertilization, and will also suggest the term of pregnancy.
Types of testing tests
There is a wide selection of tests on sale, you can buy them freely on any pharmacy, and even in the supermarket. First you need to decide which one to purchase.
Pregnancy test is effective in a few days after Monthly delays. For the strip test you will need morning urine immediately after awakening. Prepare in advance pure urine collection dishes.
To get the most accurate results, do not drink liquids and do not pose for four hours before the test. In undiluted urine, contains the highest concentration of hormone. The amount of urine will need small, about 20-30 ml. It is not recommended to shake and shake urine. It is impossible to freeze it. Storage of urine serving in the refrigerator at a temperature of from 2 to 6 ° C for days.
Care and clear execution of the manufacturer's instructions guarantee the accuracy of the result to 90 or more percent.
When buying, be sure to check the expiration date, as we do not have to talk about the accuracy of the overdue diagnostic test. Store pregnancy tests in a dry and cool place, after the expiration date - without regrets.
How to interpret the test
The test strip contains a diagnostic zone (T - TEST) and the control zone (C - Control). One painted strip during testing (in the control zone) confirms the shelf life, the second indicates pregnancy.
Visually test results may be as follows:
- In the presence of two red or pink lines (in the early deadlines, the second strip can be poorly expressed) - the test is considered positive;
- Only one strip is painted in the control zone, the second is missing - a negative result;
- Not a single strip appeared - the test does not work (this may be, if the expiration date has been output, the production technology is broken or storage).
If there is a doubt, you can repeat the pregnancy test. Some manufacturers produce sets of two or three test strips in one package. Control testing should be carried out in 2-3 days.
False positive and false negative results
There is some likelihood of pregnancy testing error. Most often this happens if the concentration of hong hong in the urine of a pregnant woman in the early deadlies is too small, and the test reagents are not captured due to low sensitivity. Other options are also possible.
False negative result (if a woman is pregnant, but the test denies it) can be obtained in the following cases:
- not enough qualitative or overdue pregnancy test;
- non-fulfillment of the testing condition - not enough accurate compliance with the instructions;
- In the event of a threat to the abortion of pregnancy, the level of hCG decreases and is not determined by the test;
- In the presence of certain diseases (for example, kidney diseases), accompanied by a violation of urine discharge, at the same time disrupted and the elimination of metabolite products.
False-positive test estimates (if a woman is not pregnant, and the test shows a positive result) more rare, and are possible in the following cases:
- If ovulation stimulation or support for the lutein phase was carried out, used drugs, proofazy. In this case, pregnancy did not come, but any pregnancy tests or a specialized blood test on Hgch will show a trace reaction within 10-14 days;
- in the presence of tumor diseases;
- After a pregnancy interrupt operation (drug or instrumental interrupt) - also for 10-14 days, the trace reaction of hormone hgch remains.
If the tests show ambiguous results, a blood test will help to clarify the presence of pregnancy (blood from the vein, surrendered strictly on an empty stomach).
It should be noted that exclude Ectopic pregnancy Using the test it is impossible, only an ultrasound examination will help.
Our site recommends reading the instructions - carefully examine the manufacturer's recommendations regarding testing.
If you have not made a test with morning urine, gynecologists recommend to refrain four hours from urination, while not to take any fluid in order to preserve sufficient urine concentration. Next carefully re-read the instructions and spend the test.
If the presence of a negative result and the continuing delay, the test is recommended to repeat after two or three days.
In the case of a positive test result, you need to consult a doctor for further pregnancy examination.
