Modern pharmaceuticals provide a woman with the opportunity, using testing devices, to independently find out whether she is pregnant or not. Gynecologists call this simple study one of the most reliable ways to determine at home whether a woman is expecting a baby. But for some reason it happens that the test gives a false result. What causes errors?
How is a pregnancy test
When an embryo is implanted in a woman's body after fertilization of an egg, a certain hormone appears in her blood and, accordingly, in her urine - human chorionic gonadotropin (hCG). To reveal it on a piece of paper industrial way a small band of specific immunoglobulins is applied - sorbed antigens labeled with colloidal gold. When antigens come into contact with urine, a reaction occurs. If the hormone is present in the liquid, then visually it appears as a red thread. If there is no hCG, or its amount is negligible, then only one control strip is noticeable on the test, indicating that the system is working. But if the test is so simple and clear, why does it sometimes fail?
Simple Mistakes
The reasons for erroneous readings of a pregnancy test can be different. For example, the expiration date of the product itself, violation temperature regime during storage or transportation, as well as improper use. According to the instructions, to obtain accurate data, a woman’s daily or better morning urine is required, it is in it that human chorionic gonadotropin is concentrated.
An incorrect reaction of the test device can occur with insufficient hormone levels if the egg is fertilized, but the embryo has not yet attached to the uterine wall. Usually this process occurs after the seventh day of conception, and only then does hCG, created by nature for the normal development of the placenta, begin to be released. However, it also happens the other way around: the test shows the presence of pregnancy, but this is not detected during a gynecological examination.
Reasons for false positive test results
The method for detecting hCG by reacting to specific immunoglobulins is used in medicine in the laboratory diagnosis of many infectious diseases and hormonal disorders. In particular, such a pathology as chorionepithelioma can also be confirmed positive test for pregnancy, although this disease is classified as oncology.
Chorionic gonadotropin is present in the body of a woman for some time after a recent abortion or miscarriage. This hormone is also found in some fertility drugs, and for this reason, the test can also show a positive result, although there is no actual pregnancy.
If the study unambiguously reveals the presence of hCG, and a gynecological examination does not record an increase in the uterus, then this is a clear sign of an ectopic pregnancy. This means that the fertilized egg has implanted in the fallopian tube and an emergency surgical intervention is required. So it happens that a test at home saves the health and even the life of a woman.
False negative results
Cases where there is no red stripe on the test, and pregnancy is developing in the meantime, are extremely rare. This is usually associated with a problem with the urinary system. For example, chronic kidney disease often leads to gross violations of the excretory function. Then the concentration of hCG in the urine is seriously reduced, even if the level of this hormone in the blood is increased.
A large intake of fluids or diuretics before the study is also likely to change the result in a negative direction, since chorionic gonadotropin will be rapidly washed out.
With atypical diseases, such as anorexia, there is often a decrease in the production of various sex hormones. In this case, a woman can become pregnant, but the level of hCG in the urine in the first three to four weeks is usually insufficient to confirm this using a standard test. And in this case, whether a woman is expecting a child can only be found out from a gynecologist.
It should also be remembered that alcohol, fatigue, stress, lactation, taking any non-hormonal drugs, as well as birth control pills, do not affect the test results in any way.
From the moment the egg attaches to the uterus, the woman's body receives information and begins preparing for it. The work of many organs is rebuilt under the influence of hormones, which begin to be produced more actively. The level of human chorionic gonadotropin, or hCG, the hormone that determines pregnancy, is constantly rising. The tests are based on an assessment of the amount of this particular substance in a woman's urine - if its level exceeds the norm for a non-pregnant woman, then the test shows a positive result, which indicates that the lady is most likely expecting a baby.
Pregnancy tests are convenient in that they can be carried out in, this does not require special equipment. They are reliable compared to other home detection methods. Tests from different manufacturers have different sensitivities: when some still fail due to too early a period and a small amount of the hormone, others already show distinct red stripes.
Most tests guarantee an almost accurate result from the first day of delay, but you need to understand that the hormone accumulates gradually, and its concentration in the urine is much lower than in the blood, therefore, the more time passes from the moment of conception, the more accurate the result will be. Doctors advise for the accuracy of the test ten days after the delay.
A pregnancy test should be done in the morning when the concentration of various substances in the urine is increased.
When is a false pregnancy test result possible?
When buying a test, check its expiration date - if it has expired, you cannot hope for an accurate result. The test can lie if it is not done according to the instructions. Read all directions on the package carefully and follow them carefully. For reliability, use two or three tests from different companies.
Pregnancy tests can show false positive and false negative results, with the latter being much more common. A negative pregnancy result is an indicator that there is still not enough hCG in the urine for the test to detect it. This happens if conception occurred a few days before the expected start date of menstruation.
If you drink a lot of water before the test, the concentration of the hormone in the urine will decrease, and the test may also show a negative result.
A positive result in the absence of pregnancy occurs very rarely and is associated either with poor-quality products or with health problems when taking certain medications that cause an increased level of hCG in the body. It can also be a sign of an ectopic pregnancy and a threatened miscarriage.
Modern pharmaceuticals provide a woman with the opportunity, using testing devices, to independently find out whether she is pregnant or not. Gynecologists call this simple study one of the most reliable ways to determine at home whether a woman is expecting a baby. But for some reason it happens that the test gives a false result. What causes errors?
How is a pregnancy test
When an embryo is implanted in a woman's body after fertilization of an egg, a certain hormone appears in her blood and, accordingly, in her urine - human chorionic gonadotropin (hCG). To detect it, a small band of specific immunoglobulins, adsorbed antigens labeled with colloidal gold, is industrially applied to a piece of paper. When antigens come into contact with urine, a reaction occurs. If the hormone is present in the liquid, then visually it appears as a red thread. If there is no hCG, or its amount is negligible, then only one control strip is noticeable on the test, indicating that the system is working. But if the test is so simple and clear, why does it sometimes fail?
Simple Mistakes
The reasons for erroneous readings of a pregnancy test can be different. For example, the expiration date of the product itself, violation of the temperature regime during its storage or transportation, as well as improper use. According to the instructions, to obtain accurate data, a woman’s daily or better morning urine is required, it is in it that human chorionic gonadotropin is concentrated.
An incorrect reaction of the test device can occur with insufficient hormone levels if the egg is fertilized, but the embryo has not yet attached to the uterine wall. Usually this process occurs after the seventh day of conception, and only then does hCG, created by nature for the normal development of the placenta, begin to be released. However, it also happens the other way around: the test shows the presence of pregnancy, but this is not detected during a gynecological examination.
Reasons for false positive test results
The method of detecting hCG by reacting to specific immunoglobulins is used in medicine in the laboratory diagnosis of many infectious diseases and hormonal disorders. In particular, such a pathology as chorionepithelioma can also be confirmed by a positive pregnancy test, although this disease is referred to as oncology.
Chorionic gonadotropin is present in the body of a woman for some time after a recent abortion or miscarriage. This hormone is also found in some fertility drugs, and for this reason, the test can also show a positive result, although there is no actual pregnancy.
If the study unambiguously reveals the presence of hCG, and a gynecological examination does not record an increase in the uterus, then this is a clear sign of an ectopic pregnancy. This means that the fertilized egg has implanted in the fallopian tube and an emergency surgical intervention is required. So it happens that a test at home saves the health and even the life of a woman.
False negative results
Cases where there is no red stripe on the test, and pregnancy is developing in the meantime, are extremely rare. This is usually associated with a problem with the urinary system. For example, chronic kidney disease often leads to gross violations of the excretory function. Then the concentration of hCG in the urine is seriously reduced, even if the level of this hormone in the blood is increased.
A large intake of fluids or diuretics before the study is also likely to change the result in a negative direction, since chorionic gonadotropin will be rapidly washed out.
With atypical diseases, such as anorexia, there is often a decrease in the production of various sex hormones. In this case, a woman can become pregnant, but the level of hCG in the urine in the first three to four weeks is usually insufficient to confirm this using a standard test. And in this case, whether a woman is expecting a child can only be found out from a gynecologist.
It should also be remembered that alcohol, fatigue, stress, lactation, taking any non-hormonal drugs, as well as birth control pills, do not affect the test results in any way.
Time: 12:09 The date: 18/04/02
Help me to understand! I have a delay of 1.5 weeks (this has never happened before) and there are no signs of an approaching period either. I did three different rapid pregnancy tests, but the result is zero (i.e. the tests show that there is no pregnancy. Is it possible that the tests show incorrectly?
Time: 13:06 The date: 18/04/02
It's very possible. I didn’t show a damn thing until 6 weeks, I already went to the gynecologist and she manually felt everything there, that there was a pregnancy, and he gave a negative result.
Time: 13:16 The date: 18/04/02
obychno HOROSHI pesty ne vrut. u menja opredelili na sroke kogda betta byla 29 (nu ochen "malen" kaja)
Time: 13:19 The date: 18/04/02
Still like lying. It is usually believed that they are lying in the direction of not showing pregnancy if there is one, but here on the old forum one girl wrote that her husband had a positive pregnancy test.
In order not to suffer and not to guess whether the test is lying or not, it is better to take a BLOOD test for hCG. The most accurate thing possible.
Time: 16:25 The date: 18/04/02
as the doctor once explained to me, the test can be negative in the presence of pregnancy, if the deadline for determining it is missed. Simply put, on the first day of the delay, the test would be positive (if there is a pregnancy), and after a few days the test will show stubbornly 1 strip.
I don’t know how true this is, because. I always went to the doctor to calm down, which I advise you.
Time: 17:37 The date: 18/04/02
It may well be, although I personally found pregnancy with a test. On the other hand, my pregnancy was then 10 weeks, no less. But my doctor definitely confirmed the pregnancy.
Time: 08:11 The date: 19/04/02
Tests can lie (toward the denial of pregnancy). Fertilization of the egg by a sperm occurs in the fallopian tube, after 14 days (for each woman individually, a month may pass), the fetus enters the uterus, after which the hormone begins to be produced, to which the 2nd strip in the test reacts, and only then can we say, that the woman is pregnant, although all this time she has already been in an "interesting" position. If the tests do not show pregnancy, then you should not postpone a visit to the gynecologist for a long time. But delays can be from stress and from changing belts. How is your general condition? I knew that I was pregnant a week later without any tests, so much and in such quantities, I never wanted condensed milk.
Time: 09:16 The date: 21/04/02
They can lie! And how
Time: 21:50 The date: 22/04/02
And I have tests 3 months. showed pregnancy, ultrasound showed her absence. As a result, it turned out to be a bad disease. Sorry, I'm not scaring, just sharing my experience.
Time: 11:51 The date: 23/04/02
Didn't lie for 4 years. If there are any violations, the 2nd stripe can really blink.
And so far they didn't lie. Even a month ago - more than a week there was a delay - the test stubbornly showed "no", I no longer believed, and suddenly M ...
Time: 13:58 The date: 23/04/02
Go see a doctor. They will do a blood test or look at an ultrasound scan and everything will be determined: there is a pregnancy or not. Because if there is no pregnancy, a cycle failure for such a long period of time is not very good sign. I would not have endured so much time of uncertainty, I would have run away long ago.
Time: 13:40 The date: 27/04/02
And I have a joke with this - quite often I donate blood to the laboratory of the Central Clinical Hospital, where they check it for everything and everything and they always tell me that I am pregnant) Although special. they don’t do a test, but they speak according to some of their signs.
Time: 15:44 The date: 28/04/02
I have a lot of experience with rapid tests, I have been doing it for five years. They have never let me down. With long delays, I did 100 times, they always showed the absence of pregnancy. And when I got pregnant, I found out about it from the express test.
In my opinion, the most important thing to do is:
- preferably use morning urine,
- evaluate the result after 1-5 minutes, and not 10-20, because after 10-20 minutes, a second strip usually always appears,
- and remember that even the weakest second strip (if you can see it) means that you are pregnant
By the way, when I was in the hospital, doctors, if they urgently needed to determine pregnancy, also used them.
Time: 09:09 The date: 08/05/02
Rarely. At healthy women with a normal hormone content, good tests practically do not lie. You can take a blood test for hCG, do an ultrasound - this is to make sure completely.
Time: 22:26 The date: 10/05/02
Since the moment of pregnancy, I have done a test within a month 6 times ("Be sure") and not once did it show pregnancy. It only became clear when I went to the doctor. And somewhere in the second month, the test showed a weak second line. Like this.
Time: 14:06 The date: 20/05/02
By the way, I took a negative test yesterday. I have a delay of 6 days, and last month there was no menstruation at all, but the doctor said that there was no pregnancy. But I didn’t find any tfu-tfu diseases associated with the absence of menstruation either, she says the cycle needs to be stabilized and prescribed hormones, but I don’t drink them . this time I'm waiting, I don't know the signs of pregnancy, therefore I don't see them, but there seem to be no signs of menstruation. so. I don’t know what to do .. maybe already))) I hope ....
Time: 04:05 The date: 29/05/02
three in a row, unbelievable. Maybe wait for an ultrasound?
Time: 21:56 The date: 04/06/02
If all your knowledge about pregnancy tests is limited to stories about "two stripes", then this article is what you need ..
What is a pregnancy test and how does it work
Pregnancy tests look for a substance in your blood or urine called human chorionic gonadotropin (hCG). This hormone begins to be produced at the very moment when a fertilized egg attaches to the wall of the uterus.
Usually - although not always - this happens six days after conception. In the event of pregnancy, the level of hCG begins to rise extremely rapidly, doubling every two to three days.
What are the pregnancy tests
In general, they can be divided into two groups: blood tests and urine tests.
You can conduct a urine test not only in a medical office, but also at home. These rapid tests are simple and convenient. To achieve the most reliable results, carefully follow all the rules described in the instructions.
Blood analysis is carried out only in medical institutions. This method allows you to detect pregnancy at a very early dates, however, for obvious reasons, the results need to wait longer than with a urine test.
Blood tests for hCG are of two types:
1) Qualitative test - states the presence or absence of hCG in the blood. In fact, it only gives an answer to the question "Are you pregnant?".
2) A quantitative test (beta-hCG) measures the exact amount of the hormone in the blood. The sensitivity of this test is extremely high. Knowing the exact concentration of this hormone makes it possible to track problems that occur during pregnancy. In addition, this test is absolutely essential for diagnosing an ectopic (tubal) pregnancy.
How accurate are pregnancy tests?
For reliable definition pregnancy must wait at least ten days after the delay. It is advisable to carry out the test in the morning when the urine is as concentrated as possible.
Home rapid pregnancy tests are approximately 97% accurate. The following factors can influence this indicator:
1) Careful observance of all instructions.
2) Timing of ovulation and implantation of the egg in the uterine wall.
3) Suitable Choice deadline for the test.
4) The sensitivity of a particular test.
The price of the test and the difficulties in using
You can buy a pregnancy test at any pharmacy without a prescription. The price depends on the manufacturer. For the most part, they are inexpensive: the price range varies from 80 to 800 rubles, rarely more expensive.
The operation of home tests usually does not cause difficulties. The most convenient tests that can be held directly under the stream of urine, but there are other options: some strips are prescribed to be placed in a glass of urine, others must be dripped with a pipette.
Be that as it may, after contact of urine with the strip, you need to wait a few minutes to get the result. The latter may appear as a stripe, color change, or symbols (eg "+" or "-"). They also sell advanced digital tests that will make you happy with the word "Pregnant" on the display.
How to interpret test results
It is important to know what a positive and negative pregnancy test result means.
If the result positive means you are pregnant. And it doesn't matter how faded the strip, symbol or sign is highlighted. In rare cases, there are so-called conditionally positive results: when, according to the test results, pregnancy has occurred, which is actually not true. Such errors may be associated with the presence of protein or blood in the urine, as well as with the use of certain drugs (tranquilizers, anti-convulsants, and others).
Negative The result means that most likely you are not pregnant. However, the opposite is also possible if:
1) the test strips have expired,
2) you violated the rules of operation,
3) you took the test too early,
4) you have too dilute urine due to the fact that you drank a lot of water the day before,
5) you are taking certain medications (such as diuretics and antihistamines).
If you get a negative result, just in case, repeat the test in a week to be sure.
If you get different results after several tests, see your doctor. Perhaps it's time to do a blood test for hCG.
