Pregnancy tests: how much can they trust?

Do you have doubts about whether you are pregnant? Of course, you need to go to the doctor. However, to begin with, you can try and determine it yourself by buying a pregnancy test.

How do pregnancy tests work?

The principle of the tests is based on the production of chorionic gonadotropin.

The test, interacting with urine, begins the search for the hCG hormone, sometimes called the hormone of pregnancy. It begins to develop after 7 days from the onset of pregnancy, immediately after attaching a fertilized egg to the walls of the uterus. In this case, the level of hCG every couple of days increases. The process is rather slow, for this reason it is difficult to get absolutely correct results in the first days of pregnancy . Since before the implantation, even when fertilization has occurred, this hormone is not yet developed, and it is impossible to determine the presence of pregnancy.

But only a week after fertilization, the concentration of gonadotropin in the urine reaches a level that can be caught with the help of a test. Usually, firms that make pregnancy tests write on packages when it is possible to get a reliable result. This depends on the sensitivity level of the tests, usually indicated on the package. The lower the figure indicated on the packet, the higher the sensitivity of the test, therefore, the earlier the pregnancy can be determined. Pregnancy tests that have a sensitivity of 10, can be used for 7-8 days from the time of ovulation. But it is not always possible to determine the exact date of ovulation, so the test before the delay in menstruation should not be held, because then there is the risk of a false-negative result. A reliable result can be obtained only after a delay in the months.

How to conduct the test?

For the most part, the tests are a strip of paper impregnated with a special substance. This substance, in contact with the gonadotropin, changes its color.

Before the test, you should read the instruction carefully, as all tests based on one principle differ in small things, but just such small things can influence the results.

As a rule, morning urine is needed to determine pregnancy. A test strip is lowered into it to a certain label. Through the time indicated in the instruction, the strip must be removed, and the result should be read no later than 5 minutes later.

Please note that the test result is not absolute, but probable. And his confirmation gives an examination at the gynecologist. In addition, a positive result does not exclude the possibility of developing an ectopic pregnancy, and this condition is very dangerous, and requires urgent consultation of the doctor.

What are the pregnancy tests?

1. Most likely, in the pharmacy you will be offered a test strip, impregnated with a special reagent. By the method of application, these tests are very simple: it is necessary to collect urine (preferably morning, in which the concentration of the hormone is higher) into a clean container. Which side to omit the pregnancy test is indicated on the package: there is a mark on the surface of the test that is the control. If a second appears next to it, you are pregnant. Reliability on the first day of delay, on average, 85-95%. A week after the absence of menstruation, it already reaches 95-100%.

This test is the easiest, cheapest and popular. But they are inaccurate. First, the reagent can not be saturated with urine and give an incorrect result. Secondly, if the test is deeper, overexposed or underexposed, the reagent will be washed away, the result will be incorrect.

2. The second group is tablet tests, they are more reliable, but also cost more. This is the same strip, but in a plastic tablet. This test in urine is no longer necessary. On its front side there are 2 windows. In the first window you need to drop a little urine, in the second in a couple of minutes you can see the result. If there is pregnancy, the reagent will take on color.

3. Today, the most effective test is considered an ink jet. Inside such tests there is a layer of blue particles, they attach instantly to the hCG hormone in a drop of urine (in the presence of pregnancy), making it visible. The result will be visible in a minute, and it is quite reliable, almost 100 percent.

The inkjet tests have many advantages over the others, since they can be applied at any time of the day and under any conditions. You just need to substitute the test for a stream of urine, and a minute later you will know the result. At the same time to determine the pregnancy enough small amount of the hormone.

Do pregnancy tests always tell the truth?
The test gives an error in some cases. Basically, the reasons for this are:

1. Violation of storage of the test;
2. An early test may not determine pregnancy due to a small concentration of hCG;
3. Non-observance of the instruction also contributes to an unreliable result;
4. Sometimes an increase in the hormone content is due to the tumor process in the organs of the reproductive system. Then the test, even in the absence of pregnancy, can show a positive result;
5. There may be a violation of the test production technology or the use of substandard reagents.

In any case, if in doubt in the results, repeat the test in a couple of days. But more reliably on the question of the presence or absence of pregnancy can answer the gynecologist, as well as the results of a blood test for hCG and ultrasound.