In what cases is a pregnancy test deceiving. Why pregnancy tests often lie. Reasons for false positive test results

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.

Hello, dear girls and women! Well, if you are interested in the question of when to take a pregnancy test, then it is unlikely that you will wait for the next morning, and even more so for a delay in menstruation, to do everything properly and in accordance with the instructions.

Of course, you want to know the result right now and you probably already have a pregnancy test in your hands. That's just how reliable the result will show a pregnancy test in the evening or in the afternoon? Let's figure it out.

Perhaps you want to conduct a pregnancy test for the first time, or maybe you have already performed such a diagnosis of pregnancy on your own more than once and you know how to use a pregnancy test, that’s not the point. This material will be useful in any case.

Why are we sure of this, yes, simply because quite often modern tests, especially an early pregnancy test, show an erroneous result. And it is not always necessary to blame the test manufacturer for this, often and very often we ourselves are to blame because we do not follow the instructions. And we just don’t know how a pregnancy test works in principle.

What you need to know before taking a pregnancy test?

You probably already know that during pregnancy in a woman in the blood, and a little later in the urine, the level of the hCG hormone begins to increase. And any pregnancy test, reacting to the presence of this hormone, gives us a second strip.

But what determines the accuracy of the test? Firstly, it must be said that hCG begins to grow after implantation of the fetal egg in the wall of the uterus - this, so that you understand, can only occur 7-10 days after ovulation.

Secondly, the level of hCG is growing gradually, every day, increasing, and thereby reaching the required level. About 12-15 days after ovulation - this is the time when the pregnancy test shows 2 strips.

Thirdly, tests come in different sensitivities. For example, the strip-strip test has a sensitivity of 25 mIU/ml and can detect pregnancy from the first day of a delay, a jet (10 mIU/ml) pregnancy test after conception detects pregnancy 5 days before a delay.

In general, if it is logical to argue, then if the hCG hormone is present in the blood and urine, then it will be there regardless of the time of day. However, if you do an early pregnancy test, the terms are still small, then it turns out that this hormone is not quite enough for a high-quality diagnosis.

That is why it is desirable to carry out the test in the morning, when the concentration of the hormone in the urine is maximum and the test can detect hCG. In order for the test to show the most accurate result, it is advisable to follow the following recommendations:

• test in the morning, urine should be fresh. And not so that they collected urine, and then went to buy a test;
• do not drink a lot of liquid before the test;
• If you are taking a pregnancy test during the day, try not to urinate for at least 4 hours.

And, of course, carefully read the instructions for the test, the accuracy of the result will depend on how you use the test and at what time.

What happened, why is the pregnancy test lying?

We are already used to negative pregnancy tests in the early stages, and in this case everything is understandable, as we talked about above, but how does a pregnancy test 2 strips turn out in the absence of pregnancy, such a test is also called a false positive pregnancy test?

As you already understood, the test shows us the presence of the hCG hormone in the body. If there is no pregnancy, then the following reasons for the increase in the hCG hormone are possible: a recent termination of pregnancy (miscarriage or abortion); interrupted ectopic pregnancy; the use of drugs containing hCG.

By the way, it is often not a pregnancy test that can be wrong, but girls perceive a blurry, barely noticeable slurred second strip as a positive pregnancy test result. In such cases, there are two options for further action.

First - you are really pregnant, you just took a pregnancy test before the delay, and therefore, while the hormone content in the urine is too low. To confirm the result, you need to do a second test a little later or go for an examination to a gynecologist.

The second - you are not pregnant, the second strip appears because the test is of poor quality, it could have expired or the test was stored in conditions that did not comply with the instructions. Also, you yourself could have tested incorrectly.

Therefore, taking into account what gestational age the test shows, the quality, sensitivity of the test and the time it is carried out, as well as having studied the instructions that come with it, proceed to testing.

Good luck with your pregnancy test and may the result be exactly what you want it to be.

To determine early pregnancy at home, usually many women use a test that can be purchased at any pharmacy, and in general, such tests rarely lie. Want to know how often pregnancy tests lie?

How do you know if pregnancy tests are lying?

Early diagnosis of pregnancy helps to avoid many problems in the future during the bearing of a healthy child. The first signal that you are pregnant is, of course, the absence of a menstrual cycle. Also, symptoms of pregnancy can be increased appetite, excessive drowsiness, nausea, vomiting, dizziness. However, sometimes these symptoms are not enough for a woman to establish pregnancy, or they are not fully manifested, and then she decides to use a test to determine pregnancy.

When is a pregnancy test false?

It is worth remembering that a home test sometimes lies and will not always be able to show the correct result. Both false positive and false negative results are possible under the following conditions:

• kidney disease;
• Taking hormonal drugs that contain the hCG hormone;
• Drinking large amounts of liquid, which flushes the hormone out of the urine;
• Ovarian cyst, gynecological tumors;
• Risk of miscarriage;
• Ectopic pregnancy;
• Test sensitivity level. To detect pregnancy already on the 7th day, a test with a sensitivity of 10 Mme / ml is recommended;
• Implantation of a fertilized egg into the uterus can occur on the 10th day after fertilization, so the concentration of hCG is insufficient to determine pregnancy;
• Violated the expiration date and storage of the pregnancy test;
• The packaging of the pregnancy test was broken, moisture got inside;
• Failure to follow the instructions for using a pregnancy test.

For a reliable result, you need to contact a gynecologist who will prescribe a test to determine the level of the hormone in the woman's blood. Such a test does not lie, as it is carried out in a clinical setting and helps to determine the growth dynamics of the hormone, show an ectopic pregnancy, prevent miscarriage or fetal fading.

Can I take a pregnancy test during my period?

Undoubtedly, if a woman notices all the symptoms of pregnancy. Usually, ovulation in many women and girls occurs on the 13-14th day of the menstrual cycle. When fertilization occurs in this cycle, the egg only reaches the uterus on days 7-15. If the implantation occurred later than usual, then menstruation may begin. There are cases when two eggs in different ovaries mature in one cycle, and if one is fertilized, then the other leaves along with the endometrium, forming menstruation. A positive pregnancy test during menstruation is also possible in the presence of a hormonal disorder, an ectopic pregnancy, or a threatened miscarriage. In any case, even if a woman does not think that the pregnancy test is lying, you should consult a doctor.

How does the test determine pregnancy?

The pregnancy test is an indicator of the hormone hCG (human chorionic gonadotropin). This hormone is released by the fertilized egg after the fertilized egg has passed through the fallopian tubes and implanted in the uterine cavity. This usually occurs on the 6th day of pregnancy, while the hormone in the urine increases every two to three days, and decreases only by the tenth week of pregnancy.

What do the stripes on a pregnancy test mean?

The pregnancy test contains a special indicator that is able to bind hCG, while changing its color if the concentration of the hormone exceeds the sensitivity threshold of the indicator. The first strip of the test shows that it is suitable for consumption, and the second indicates the presence or absence of pregnancy. Even a weak color of the second strip indicates pregnancy, since the presence of the hormone changes over time in the woman's body. Subject to all the rules for using the test, it has a 98% guarantee.

A pregnancy test will help to identify the interesting position of a woman in the early stages and signal changes in her body. But only a gynecologist in a hospital can make the most accurate diagnosis, so after discovering the treasured two strips, you should not delay a visit to the doctor.

The vast majority of women dream of becoming a mother. Most do not have problems with this, but some face various difficulties on the way to the birth of a child. Both of them react to the delay in menstruation with the hope that the conception has successfully taken place and soon they will give rise to a new life.

Rapid diagnosis of pregnancy

Modern pharmacy and healthcare offer women the ability to quickly find out if a delay is due to pregnancy. To do this, a lot of quick tests are produced that you can use on your own at home. They are very popular, because they provide significant opportunities:

• Save time - no need to go to the laboratory, consultation or clinic.
• Convenience - the study can be carried out when there is a desire.
• Availability - can be bought at the nearest pharmacy.
• Simplicity - no effort required, just urinate and that's it.
• High accuracy of the result.

What emotions to experience with a positive or negative result is the business of each woman individually and at a particular time. But what if the test is wrong? Do pregnancy tests lie in principle or are their results final?

It happens that with a negative express test, menstruation does not come, then the tummy begins to grow, and the chest fills up. There is another option, when a positive result does not mean anything. Regulations come some time later, which means a new delay on the path to motherhood.

The principle of quick tests

Any test is based on an enzyme-linked immunoglobulin (antibody) reaction. These proteins are designed to interact with human chorionic gonadotropin (hCG), which is called the hormone of pregnancy.

After conception, the embryo attaches to the wall of the uterus, and the mother's body begins to intensively produce hCG to allow a normal placenta to develop. During 10-14 days of pregnancy, its concentration in the blood increases by 5-25 times. It is excreted by the kidneys, so now you can catch it in the urine, which is what rapid tests allow you to do.

In our world, no one can give absolute guarantees for anything. This thesis is fully applicable to pregnancy tests. Their reaction depends on many factors that cannot always be influenced.

Even the instructions for use indicate that the result is reliable in about 97-98% of cases. In reality, the accuracy of home analysis barely reaches 75%.

However, to say that the tests lie is not worth it.

Specificity and sensitivity

All laboratory studies have two characteristics that are decisive for a reliable result. The first ability of a test to respond solely to a "target" is called specificity. The second is sensitivity and shows how likely it is that a reaction to the detection of a “target” will occur.

Regarding the diagnosis of pregnancy, this means the following:

1. A highly sensitive test will confidently respond to an increase in hCG levels.
2. A highly specific test will only respond to hCG and not to any other compounds.

In our time, there is still no pregnancy test, whose specificity and sensitivity would reach 100%.

So always pay attention to the instructions. It indicates how much you can trust the result obtained with careful observance of all recommendations for use.

What might be the result and why?

The error of the test can be observed in both directions. If the test showed low sensitivity, we are talking about a false negative result. A false positive reaction will be noted if the specificity is violated. Incorrect results in both cases can be caused by many factors. So, tests can cheat when:

• Non-compliance with production technology. Unfortunately, poor-quality fakes are found.
• Violation of the rules of storage and transportation. Most often, accuracy is affected by non-compliance with temperature and humidity requirements on the way to the consumer.
• Expiration date.
• Incorrect use.
• Changes in the hormonal background in the body of a woman.
• Various diseases that affect metabolism.

The influence of some factors (manufacturing and storage) on the result is almost impossible to take into account. The rest can be provided. The consultation of a qualified physician will be of great help in this.

False negative results

With the conception that has taken place, you can easily encounter a negative test response. This situation is most often observed in such cases:

1. Too early use. Sometimes there are recommendations to conduct a study from 4 days after the delay. A low concentration of hCG makes the test lie that there was no conception.


2. Incorrect collection of urine. For analysis, you need to take only the first morning portion. It is the most concentrated and the content of chorionic gonadotropin (if it is there) is sufficient to obtain a result.
3. Pathology of the urinary system. Chronic kidney disease can lead to gross violations of the excretory function. The result will be a decrease in the concentration of hCG in the urine, even if its level in the blood is elevated.

The easiest thing to do is to repeat the test after a couple of days, strictly following the instructions. Ideally - 12-14 days after the first day of delay. Before the second study, it will not be superfluous to take a routine urine test in the laboratory of the clinic and make sure that everything is in order with the kidneys. Then the probability of being deceived by the test is significantly reduced.

False positive results

A positive answer should not be blindly trusted either. Especially if time passes, and other signs of pregnancy keep you waiting. A false answer can be if the level of hCG in the urine is elevated, but this is not associated with the development of the embryo. Most often this happens when:

1. Carrying out the analysis shortly after the termination of pregnancy (spontaneous or medical).
2. Hyperproduction of chorionic gonadotropin in some tumors.
3. Stimulating the synthesis of this hormone with medications in the treatment of infertility.
4. Direct introduction of hCG into the body. For example, for the treatment of certain cancers.

Very rarely (but in medicine such cases are described) the so-called false pregnancy can be observed. A woman begins to believe in her pregnancy so much that her metabolism changes. The hCG level rises and makes the tests lie. In this case, only doctors can reliably exclude pregnancy.

It is also possible that the conception has successfully occurred, the embryo has invaded the uterine mucosa, and the placenta has begun to form. However, for various reasons, spontaneous abortion occurs at a very early stage.

The onset of such a miscarriage is difficult to track due to the small size of the embryo, and women think that the test has deceived, because they have started their periods again.

Poor quality test

If the production technology is not followed or the test has deteriorated on the way to the consumer, he can also lie. You can suspect the wrong result if you take a closer look before and after use:

1. The packaging must be undamaged.
2. It is not allowed to have any spots, stripes and color differences on the indicator area.
3. Exclude signs of physical deformation of the test itself.
4. Use only within the expiration date stated on the packaging.

The result cannot be trusted if additional strips appear that are not provided for by the instructions. Or, conversely, there is no line in the right place - manufacturers always build a response control into the system. The strips should be even, single-colored and clearly defined, occupying the entire width of the window.

With any deviation from the instructions for use, the test result can deceive.

Research in the hospital

The analysis in the clinic surpasses the rapid tests for home use in terms of reliability, because it is not urine that is taken for it, but blood serum. The same chorionic gonadotropin, or rather its β-subunit, is being searched for. In the blood, it appears within the first 24 hours after the implantation of a fertilized egg in the uterine wall.

The detection of this fraction of chorionic gonadotropin with high accuracy indicates the onset of pregnancy, that is, a laboratory study has greater specificity.

Nevertheless, the obstetrician's ear, which heard the fetal heartbeat and ultrasound, gives the most reliable result. The ultrasonic sensor is not capable of lying, therefore, a transvaginal examination finally confirms or refutes the onset of a physiological pregnancy.

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.