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Express pregnancy test is a system for diagnosing early pregnancy, which allows you to carry out the procedure at home. Rapid test is the general name for all pregnancy tests that exist at this point in time. Thanks to these devices, a woman can find out about the onset of conception without visiting a doctor’s office. If earlier it was possible to determine pregnancy only starting from the first day of a missed period, then the new generation rapid tests make it possible to do this much earlier.
To date, there are many varieties of rapid tests. All of them differ in the way they work, in price and in the set of functions. Therefore, in order to make the right choice, it is necessary to navigate the main characteristics of the product.
The principle of operation of the express test
All rapid pregnancy tests are based on a single mechanism of action, they determine a specific hormone in the urine. This hormone is called human chorionic gonadotropin or hCG. It begins to be produced in a woman’s body at an accelerated pace from the moment when the villi of the growing placenta are implanted in the wall of the uterus, that is, after the embryo is fixed. From this point on, the level of hCG is constantly increasing, but in the early stages of pregnancy, it can only be determined in venous blood.
Modern rapid tests can detect hCG in the urine, starting from 10-12 days from the moment of conception.
This largely depends on the sensitivity level of the device that was selected for diagnostics:
Tests with a sensitivity of 25 mIU/ml can detect pregnancy from the first day of a missed period.
Tests with a sensitivity of 15 mIU / ml can detect pregnancy 1-2 days before the date of the expected period.
Ultrasensitive tests with susceptibility to hCG at 10 mIU / ml can detect pregnancy 4 days before the date of the expected menstruation.
The principle of operation of rapid tests is based on the interaction of a special reagent with the hCG hormone. In each of these devices, a special substance is applied in a special way – antibodies to hCG. When interacting with urine, which contains chorionic gonadotropin, the test gives a reaction. Depending on the type of device, stripes may appear on it, or the result may be displayed with signs, letters, etc. If there is no hCG in the woman’s urine or there is too little of it, then the test will be negative.
Instructions for using rapid pregnancy tests
The test is best purchased at a pharmacy. This is the only way to be sure that the conditions for its storage have been observed in full.
At the time of purchase, it is important to familiarize yourself with the expiration date of the test. An overdue test may simply not work, or give an unreliable result.
The integrity of the packaging with the dough must not be compromised.
It is unacceptable to use the same test 2 times (subject to the purchase of a one-time express test).
It is better if the morning portion of urine is used for diagnosis.
You need to open the test only before using it.
Before collecting urine or urinating directly on the test, it is advisable to wash yourself well and dry yourself with a towel.
If the procedure involves the preliminary collection of urine, then for this you need to choose a clean and dry container. It can be glass or plastic.
Before using the test, you must carefully read the instructions. You should not leave her.
When is the best time to do a rapid pregnancy test?
If you refer to the instructions for the use of express tests, then the manufacturers do not indicate in them when it is best to carry out the procedure. However, gynecologists give an unequivocal recommendation on this matter – for research it is necessary to take the first portion of morning urine. This is especially true when the study is carried out at an early stage of pregnancy.
The fact is that the likelihood of an error increases when collecting urine in the daytime or in the evening. During the day, urine becomes less concentrated due to the consumption of water and other drinks. Accordingly, the level of hCG decreases in it, which may adversely affect the reliability of the results.
Pros and cons of various rapid pregnancy tests
There are several options for rapid pregnancy tests on the market. All of them have some differences in terms of their methodology:
Strip tests or test strips. Strip tests are the cheapest device among the entire range of rapid pregnancy tests, due to which they have the highest popularity among the female population. Such devices are represented by a paper strip, which is located on a plastic substrate. This paper has impregnation zones that become visible. If there is a pregnancy, then two vertical stripes will appear, and if there is no pregnancy, then one vertical stripe will appear.
For testing, you will need a clean container where urine is collected. Then a strip is lowered into it (up to a certain level), and it is kept in the liquid for about 10 seconds. After this time, the test is laid out on a dry and even surface. After another 3-5 minutes, it will be possible to evaluate the result.
Test strips, as a rule, give a reliable result if they are carried out on the first day of a missed period.
If we consider the disadvantages of such tests, then among them we can single out the not very comfortable use of strip tests and the relatively high risk of errors.
Tablet or cassette tests. These tests are flat plastic boxes with small windows. One window is a urinal, where a few drops of urine are introduced using a pipette. The result appears in the second window. Such devices are not very expensive in price, but they give a more accurate result compared to test strips.
If we consider the disadvantages of tablet tests, then among them we can distinguish the complexity of the procedure and the inability to find out the result a few days before the onset of menstruation.
Jet tests. Inkjet rapid tests are elongated devices. It is very easy to use these devices. To carry out the procedure, it is enough to bring the test under the stream of urine for a few seconds. After 3-5 minutes, the device will give the result.
Inkjet tests allow you to conduct a study a few days before the start of the expected menstruation. In addition, they are very comfortable to use.
As for the cost of such devices, it is determined by the complexity of their internal structure. If the inkjet tests are equipped with a digital screen and a USB port, then the price will be higher.
Electronic or digital tests. These devices are state of the art. Using them is very simple: their tip must be placed in the urine. To do this, you can either simply substitute it under the jet during urination, or draw liquid into a container and lower the device there. The exposure time of urine to the test is 3-5 seconds. Then it is laid out on a dry and even surface, and after another 3-5 minutes the result is evaluated. He appears in the window.
One of the advantages of such a device is that it can show pregnancy a few days before the expected period. In addition, you can purchase reusable digital tests, as well as tests with a USB port. However, the price for them will be an order of magnitude more expensive than for classic test strips.
Can rapid tests be wrong?
Although rapid tests are fairly reliable means of determining pregnancy, however, they can be wrong.
Firstly, the level of human chorionic gonadotropin in the body of each woman rises in different ways.
Secondly, the test can give a negative result due to endocrine dysfunction in women, as well as the threat of miscarriage.
Thirdly, a false negative result can be obtained if the study is performed too early. This is especially common in women with an unstable menstrual schedule.
The fourth reason why the test gives an incorrect result or does not work at all is a violation of the rules for performing the testing procedure, or a marriage of the device itself.
A woman should take into account that rapid tests can give not only false negative, but also false positive results.
Possible reasons for such errors:
The woman recently gave birth (no more than 2 months ago);
The woman has disorders in the work of the ovaries;
The woman had a miscarriage or abortion (about 30 days ago);
A woman develops a hormone-producing tumor;
The woman is taking fertility drugs containing hCG or has taken them less than 2 weeks ago;
An expired test was used.
There are cases when even after the onset of pregnancy, menstruation continues. Therefore, if a woman has doubts about this, a rapid test can be done even during menstruation. Menstrual blood cannot affect the determination of hCG in any way. Therefore, if there is a pregnancy, the test will give a positive result.
Many questions are asked by women about ectopic pregnancy and diagnostic results. As you know, in this case, the embryo located in the fetal egg is attached not to the wall of the uterus, but to the fallopian tube. Chorionic gonadotropin is produced during an ectopic pregnancy, but its level rises extremely slowly, or even stands still. Most likely, the rapid test will still give a positive result. However, the stripes may be blurry or very pale. In the early stages of an ectopic pregnancy, the test will be negative.
Sometimes there are also such pathologies of pregnancy as a frozen embryo. In this case, rapid tests first give a positive result, then it becomes doubtful, and then completely negative. In this case, you can not hesitate to contact a specialist.
So, the use of rapid tests makes it possible to determine pregnancy in the early stages of its development, without even leaving home. Thanks to a wide range of express tests, every woman will be able to choose the best option for herself.