Future mother 

Positive pregnancy test but not pregnant. False positive pregnancy test: how is this possible? How does a home pregnancy test work?

The reliability of modern home pregnancy tests is quite high, and, if performed correctly, reaches an average of 97%. A qualitative test allows you to determine pregnancy from the first day of a missed period. However, in some cases the result may be false.

A false positive test result shows the presence of pregnancy in its absence. That is, without being pregnant, a woman receives two strips on the body of the test. Why does it happen?

The reasons may be very different. And to understand why the test can cheat, let's briefly describe how it works.

A special reagent is applied to the test strip, which reacts to by binding to it and turning red-pink. The test sheet has two zones: a control zone and a test zone. The first is designed to confirm that the test is suitable for use (that is, it works properly), it simply reacts to urine. The second is manifested only if there is a sufficient amount of hCG in the urine. The most sensitive pregnancy tests are able to catch it already at the level of 25 mIU / ml. To such indicators, the hormone chorionic gonadotropin in most cases increases by the first day of the delay.

That is, in fact, a pregnancy test does not determine the pregnancy itself, but an increased level of hCG in human urine. Normally, it rises only in women and only after the fertilized egg is fixed in the uterus: the emerging (or rather the chorion) begins to produce this very human chorionic gonadotropin, which rapidly increases in the first weeks of pregnancy, doubling every two days and reaching its peak at 8-11 week. But the growth of hCG in the body (and in particular in the urine) of a person can be caused not only by pregnancy, and in principle even men can use the test to determine its level, which can become an early diagnosis of tumor development in the body.

This is because various kinds of formations are also capable of producing chorionic gonadotropin: cysts, tumors. Therefore, in the absence of pregnancy, an increased level of this hormone may indicate the course of a pathological process in the body.

HCG in the urine may remain at high levels for some time after an abortion or miscarriage. If a woman has recently been removed, then traces of hCG may also still persist.

In addition, some hormonal drugs can also increase the level of gonadotropin, affecting test results.

In addition to actually elevated hCG levels in the absence of pregnancy, false positive results may be due to the use of a low-quality test or incorrect reading of information. On some test strips, after the liquid dries, a blurry mark appears in place of the second strip, which can be erroneously interpreted as a positive result. Therefore, a warning is always written in a warning that the result is considered reliable, evaluated no later than 5-7 minutes after the test strip is immersed in urine. Please note that a positive result should be taken as the presence of a second strip, the same in color, clarity and width as the control.

So, the reasons for a false positive pregnancy test can be as follows:

  • the presence of neoplasms in the body (chorion epithelioma of the uterus, cystic drift);
  • recent abortion, miscarriage, or removal of an ectopic pregnancy;
  • taking hCG-containing medications;
  • low quality test
  • violation of the storage conditions of the test;
  • misjudgment of test results.

It should be said that false positive test results are relatively rare. Much more often, women get false negative results when, in the presence of pregnancy, the test does not show it. In the vast majority of cases, this is due to too early home testing: the level of hCG in the urine is still very low for the reagent to “detect” it.

Especially for- Elena Kichak

In view of the fact that we often so want to see the cherished // stripes, and sometimes we will even "see" them - I have collected several articles. This information may be useful. (sorry if this has already been posted)

First, an article about the frequently mentioned "liar" frautest!

FRAUTEST test

C (c o ntrol) - control zone. The appearance of this strip during the study shows that everything is in order with the system itself, the test result is RELIABLE.
T(test ) is the test zone. This strip, reacting to hCG in the urine, appears in the test zone and informs about the presence of pregnancy.

We draw your attention to the fact that the strips on the dough must be even., approximately the same color (although in early pregnancy, the test strip may be slightly lighter than the control) and placed across the entire width of the control zone.

Also follows doubt a positive test result if the strip is blurry, barely visible or located at the junction of the plastic protective substrate and the base of the test (at the test strips).

Also, a white stripe should not be considered a positive result.. A white stripe is a reagent that did not appear, which became visible due to the large amount of the test liquid that got into the test. In other words, if the woman were pregnant, then this reagent would stain and as a result, the test would show two full-fledged strips.

FALSE POSITIVE (no pregnancy, but the test shows a positive result).

Possible reasons:

- taking fertility drugs containing hCG (pregnyl, profazi) at the time of the test or if the time after the end of treatment is less than 10 days;

- the presence of tumors (chorion epithelioma of the uterus or hydatidiform mole);

- incomplete removal of embryonic tissue after a previous abortion.

FALSE NEGATIVE (there is a pregnancy, but the test shows a negative result).

Possible reasons:

- the test was carried out ahead of schedule (especially this result can be observed in women with an irregular menstrual cycle);

- pathology of the kidneys and the cardiovascular system, which prevents the release of hCG in the urine in normal concentrations;

- high fluid intake or diuretics before testing.


The mechanism of "work" of the pregnancy test

In pregnancy tests, immunochromatography is used - a type of chromatographic analysis based on the interaction of a substance (usually of a protein nature) with antibodies to it. The body's immune system works on the same principle of antigen-antibody interaction, hence the name.

The substance to be determined is human chorionic gonadotropin (hCG), a glycopeptide hormone secreted by the placenta during pregnancy. The appearance and rapid increase in the concentration of hCG in the body (and in particular, in the urine) of a woman makes it a fairly reliable sign of pregnancy. Usually, on the 7-10th day after fertilization, the concentration of hCG reaches 25 mIU / ml (international units per ml) and doubles every 2-3 days, reaching a maximum between the 8th and 11th weeks of pregnancy, and then decreases almost to zero by the beginning of the 3rd trimester. 25 mIU / ml is the minimum concentration of hCG detected using immunochromatographic tests.

How many days after ovulation can you test?

In principle, a positive result can be obtained already on the 7th day of post-ovulation. Embryo implantation takes 6-12 days, usually about 10 days. So it makes sense to wait 10-12 days after ovulation, but even then there are often false negative results (i.e., there is a pregnancy, but the test is negative).

Tests from different manufacturers have different sensitivities, most of them are designed to be used from the 1st day of a missed period. In 90% ± 5% of cases, by this time the embryo has already implanted in the uterine wall and begins to produce hCG. However, in 10% of cases, implantation has not yet occurred. With a delay of 1 week, implantation occurs already in 97% ± 3% of cases. However, in practice, the reliability of the tests is limited by their sensitivity, so the real reliability is somewhat lower. Since the hCG level doubles every 2-3 days, the recommendation follows: if the result is negative, if menstruation does not begin, repeat the test after a few days.

What do false positive and false negative test results mean?

A false positive result is when the test shows two lines in the absence of pregnancy. This happens when a woman takes drugs containing hCG, as well as with trophoblastic tumors. After a spontaneous miscarriage or early abortion or removal of an ectopic pregnancy, hCG remains in the body for some time, and the test gives false positive results (i.e. there is no longer a pregnancy, but the test is still positive). As in the case of taking drugs containing hCG, two quantitative determinations of hCG with an interval of 2-3 days are necessary to obtain reliable results. A decrease in the level of hCG indicates that the pregnancy is no longer there. Thus, false positive results are relatively rare, in contrast to false negatives. The latter are obtained when the gestational age is still too short and the hCG level is too low to be detected by the test (or the test itself is not sensitive enough).

The validity of a home test depends on various reasons:

  • The quality of the test itself. Products from different companies can vary significantly.
  • Expiration date of the test, conditions and place of its storage. It is believed that in most cases the test can be trusted, provided that it is bought at a pharmacy.
  • The state of pregnancy. In a pregnancy that is on the verge of miscarriage, hCG will be produced much less than in a normally developing pregnancy.
  • Conditions for setting the test: the study must be carried out using the morning portion of urine, in which the maximum content of the hormone is observed; the evaluation of the test must be carried out, adhering to the time interval specified in the instructions.
  • Additional circumstances. The amount of hCG in the urine is affected by the diet and the functional state of your kidneys.
  • If you drank a lot of liquid the night before, or ate a watermelon, or are taking diuretics (diuretics), the concentration of hormones in your urine will be too low, and the test will not notice them.
  • If you have protein in your urine (even if you don't know anything about it), the test may give an incorrect result.
  • If you were injected with hCG to induce ovulation (Profazi, Pregnyl) or to maintain the luteal phase, then traces of this hormone may remain in your body for 10 days after the last dose of the drug, and, accordingly, a pregnancy test may give a false positive result.
  • Also, the level of hCG can be determined several weeks after normal delivery, caesarean section, spontaneous or medical abortion, and in other cases mentioned above.

As a result, you can get incorrect information, and in both directions: there is no pregnancy, but the test seems to be positive. Or: there is a pregnancy, but the test is still negative. Both of these can be a source of great suffering.

Some tests in the absence of pregnancy show its presence (false positive result). On the contrary, there are situations when there was a pregnancy, and the test showed its absence (a false negative result).

What are the reasons for the so-called false positive and false negative results?

Often the cause of a false result is an incorrect test or the use of an expired test.

With the introduction of hCG to induce ovulation (drugs "Profazi", "Pregnil") or maintain the luteal phase of the cycle, traces of this hormone can remain in the body for 10-14 days after the last dose of the drug, and, accordingly, a pregnancy test can give false positive result.

Alcohol, fatigue, stress, lactation, taking medications (including birth control pills and Postinor) do not affect the test results.

The cause of false positive results may be a tumor that produces hCG - chorionepithelioma or cystic drift, dysfunctional ovarian diseases, when the production of various sex hormones is impaired.

After a spontaneous miscarriage or early abortion or removal of an ectopic pregnancy, hCG remains in the body for some time, and the test gives false positive results.

If you notice any changes in your body (for example, a missed period), then you may be pregnant and a positive pregnancy test can confirm this. Of course, this is not an absolute truth, because in addition to pregnancy, unfortunately, there are many diseases of the female reproductive system that can prevent the timely onset of menstruation.

But if you didn’t take it, you are regularly observed by a gynecologist and you know that everything is in order with your health, then the delay, in fact, may indicate fertilization and the birth of a new life that has occurred inside you. This can be understood not only with the help of a antenatal clinic specialist, but also as a result of the use of special pregnancy tests, which every woman has an idea about.

What to do if the test showed a positive result? Naturally, you should not immediately report this wonderful news to all relatives and friends.

In addition to the state of pregnancy, there are many other reasons why the test may give a positive result. These reasons include:

1. Incorrect use of the test.
2. Expired date, damaged outer packaging or improper storage of the dough.
3. The use of the test at an early stage after a short time after unprotected intercourse. In the first days of pregnancy, the concentration of hCG in a woman's body is very low, and the tests simply cannot react to the presence of this hormone.
4. Impaired ovarian function can also affect the result of a pregnancy test.
5. Taking contraceptives.
6. Irregular cycle. If the interval between periods is always different, then the veracity of the test should be hoped to a lesser extent.
7. Many women are at risk of developing abnormal pregnancies, such as ectopic pregnancies. In this case, the test can give a positive result, but, unfortunately, it informs about the existing pathology. Not able to.

If you bought a working test, followed all the rules for its use specified in the instructions, and also if you do not have any diseases and disorders in the female plan, then the two strips that appear on the test are more likely to indicate a pregnancy that has occurred actually in your body.

But be that as it may, regardless of the result of even several tests in a row, you should consult a gynecologist. Only he will be able to give you a 100% truthful answer not only about the presence or absence of your pregnancy, but also about the nature of its course. And prevent pregnancy.

And the most important thing to remember is that a positive pregnancy test is something that will change your life drastically. Now you are not just a woman, you are a future mother who is simply obliged to provide her baby with all the conditions for a full intrauterine development. And then, in nine months, your healthy baby will cause you a huge surge of positive emotions with his first cry.

Nowadays, to find out the reason for the delay in the onset of menstruation, it is enough to buy a pregnancy test at the pharmacy. Such test methods, carried out at home, give almost 98% reliable results. Nevertheless, one can often hear the question: “Can a pregnancy test be false positive?”. Unfortunately, there are many errors in testing and you should be aware of them and take into account.

Sometimes the express method can determine a positive test in the absence of pregnancy. That is, there are two strips on the indicator line, but the woman is not in position. In what cases can a test show false data? What do we have to do?

Pregnancy diagnostics

The diagnostic device consists of a strip impregnated with a special reagent. As soon as a woman becomes pregnant, chorionic gonadotropin begins to accumulate in her urine almost from the first days. It is he who interacts with the reagent, appearing visually in the form of two strips. But hCG may be present for other reasons, they are not always explained by fertilization.

Expectant mothers should not rush to take tests the next day after a possible conception, it is better to wait for obvious signs of pregnancy.

Among them, the most common:

  • Delayed monthly cycle.
  • Nausea and vomiting, especially in the morning.
  • Irritation.
  • Constant weakness and drowsiness.

The strip is very sensitive, so use it only after carefully reading the insert.

What influences the result?

There is no pregnancy, but the test is positive. This can happen, and more than once. What is the problem? In many situations, the human factor affects, as well as the environment.

We divide the possible causes into small groups:

  • No wonder we are given instructions for use for a particular device. But not every woman carefully studies and, when using, does not always listen to the prompts. For example, this applies to a container for collecting urine - it must be clean and sterile. Violating such a simple point, you can get a false positive test. The reasons why this will happen, I hope you understand.
  • Improper storage of the test in a pharmacy and at home, after purchase. The purchased box should be stored in a dry place out of the reach of small children.
  • Another important point. Errors can be when taking indicators. If you put the strip into a container of urine and immediately took it out to see the results, this is wrong. In any case, the packaging or instructions indicate the required time to wait after you have immersed the test in urine. Most often from 5 to 7 minutes. It is important to understand that the result can be considered positive only if you observe the presence of two clear and evenly colored bands on the test.

As you can see, the reasons for a false positive pregnancy test are different, one of them may be the manufacturer. If poor quality reagents are used, the test response may be inaccurate.

False positive result

A false positive pregnancy test needs a mandatory consultation with a gynecologist. At home, the manipulation is repeated, for this they take a set from another company, for example, Evitest, and the result is determined by a third party, it can be a mother, girlfriend or sister.

Also, the doctor can prescribe a blood test for the presence of a hormone, only thanks to him can you say with confidence "I'm pregnant" or vice versa.

So: if there is no pregnancy as such, and the test answer is positive, then they speak of a false positive answer. If there is a pregnancy, but the answer is negative, they speak of a false negative result.

System errors

The test is positive, but there is no pregnancy - this happens much less often than a false negative answer, and there are reasons for this.

Here are the main ones:

  • The expiration date of the drug has expired or there is a defect in it. When buying products in a pharmacy, be sure to check whether they are still fit for use. If the deadline has passed, it is no longer possible to apply the test, since most often the result will be false. In the case of a marriage, it is more difficult, because when buying, we cannot verify the integrity of the packaging and the test itself. In this case, you will have to repeat the manipulation after a few days, using a strip of another company.
  • Instruction violation. If you use this method of home diagnosis at will, you are guaranteed a false positive pregnancy test. By purchasing a regular test strip and substituting it under a stream of urine, or vice versa, lowering an inkjet test into a container, you violate the correctness of the analysis, or rather, the instructions. The test strip should be kept in a container with urine strictly for the time specified in the instructions.
  • Miscarriages, abortions, or ectopic pregnancies. In the presence of at least one of the listed cases, the level of hCG does not decrease quickly, this takes time. Therefore, when conducting home testing, the result may be positive, but there is no pregnancy. In this case, it is advisable to wait a while. If you are sure of fertilization, repeat the analysis.
  • Tumors in the female body. If menstruation is late, can there be a false positive result? Oddly enough, yes, a positive pregnancy test is due to the presence of an ovarian cyst or tumor formations of both the reproductive system and other internal organs. Therefore, if you have a delay, and the analysis is positive, you should not rejoice ahead of time. In this case, make an appointment with a gynecologist and undergo a complete examination to confirm pregnancy.
  • Taking medications that contain human chorionic gonadotropin. A woman can take medications, such as Pregnyl, to stimulate ovulation. Therefore, it makes no sense to do a test, because the hormone is completely eliminated from the body only after two weeks.

When your result is false positive, you need to take into account all the indicated reasons for the appearance of this indicator. If you feel that any of the items matches your condition, please consult your doctor for advice.

Error rate

From everything that has been said before, you can conclude that you cannot rely on such quick checks, as they often give the wrong answer. But this does not mean that they are of poor quality.

Doctors have their own opinion about this type of diagnosis. According to statistics, in 98% of cases, the diagnosis is correct, which indicates the sensitivity and accuracy of this express method.

Are the tests wrong? Definitely yes. And this should be taken into account in the analysis. In any case, independence in such a matter is inappropriate, only a doctor can help you answer the question of whether you are pregnant or not.

Dear ladies, you should take care of your health, so it’s better to visit a doctor once again than to regret later about the missed time or wasting nerve cells. A pregnancy test will be positive only if all the recommendations specified in the instructions are followed, and also if your egg is fertilized.

So take your time, you can check for pregnancy later. Love yourself and your future children. It doesn't matter if you end up with a false positive test or pregnancy, it's your health that matters most. New life should be born in love, family harmony and good health, so work on yourself before you take such a responsible step and purchase your first test at the pharmacy.

Pregnancy or only its probability is always associated with worries and experiences. What is at least the period when a woman with bated breath takes the first pregnancy test, perhaps even before the delay of menstruation, waiting for the result of endless 5 minutes! Then another wave of emotions follows - of a different nature, depending on the result obtained. But another one can follow it if the test result for some reason turns out to be untrue. That is why experts recommend that you never limit yourself to a one-time pregnancy test at home, or after a few days (or even immediately, depending on the expected period), go to the gynecologist for an examination. The test can always be wrong!

Most often, women experience false negative results when it comes to errors. But false positives also happen, when the test shows pregnancy in its actual absence.

What can affect the distortion of the real picture and why the test is lying - let's see.

Elevated levels of human chorionic gonadotropin

There is a specific hormone in our body called human chorionic gonadotropin, or hCG for short. In the early stages of pregnancy, he is at the head of the entire hormonal fraternity, but in everyday life, in the normal state, the value (and especially the level) of hCG is not so great.

Normally, human chorionic gonadotropin is present in the body of every person - both men and women - but in a very modest concentration of no more than 5 mU / ml.

A physiological increase in the level of hCG occurs only with the onset of pregnancy, because the resulting chorion (the membrane of the fetal egg developing inside the womb) begins to actively produce this hormone immediately after attaching to the uterus.

For diagnosing pregnancy in the early stages, this property is very beneficial and convenient: a few days before the delay in menstruation, an increasing concentration of hCG in the blood can easily be detected by a laboratory blood test, and a few days later, a home pregnancy test. The action of the latter is based on determining the presence of this hormone in the urine of a woman when it rises to a certain level. The reagent hidden in the test second strip reacts with hCG, which is indicated by the manifestation of this very second strip on the test sheet. The greater the delay in menstruation, the higher the likelihood that the test will show an onset of pregnancy.

Therefore, if the level of hCG in the woman's urine is high enough for the test to detect it, the test result will be positive. However, an increase in the concentration of chorionic gonadotropin is not always associated with the development of pregnancy. There may be other reasons for this.

The first and most obvious is a pregnancy that aborted for some reason or ended naturally and successfully in the recent past. If there was a frozen, ectopic or any other pregnancy that ended in an abortion or miscarriage, as well as after childbirth (including Caesarean) for a certain period of time (over several weeks), the level of hCG in the woman’s body will still be quite high, decreasing gradually.

Medications containing the hormone chorionic gonadotropin are also capable of changing the hormonal background. If a woman is undergoing such therapy, then a false positive pregnancy test will be associated with treatment.

Disruption of the hormonal balance and an increase in the level of hCG in the blood and urine can provoke trophoblastic tumor formations: they also, like the chorion during pregnancy, produce the hormone gonadotropin, or rather, they are formed from trophoblast cells - the one that is able to produce hCG.

Thus, if you receive a false positive pregnancy test result, then you should exclude the likely pathological causes of the error associated with health problems.

But much more often, the causes of a false positive pregnancy test are quite harmless in nature, not associated with any diseases.

Violation of the rules of the test

It is quite obvious that since the instructions for each test describe the procedure for conducting it in such detail, the sequence and correctness of all steps affects the reliability of the result.

It often happens that women overexpose the strip in the urine longer than the time indicated in the instructions (usually, it is 5 minutes) in order to definitely get the correct result. However, such actions lead to the fact that the reagents get too wet - and when this moisture evaporates, a fuzzy, blurry second strip may appear, when, according to the rules, it should not appear.

A similar effect can be observed on test strips of poor quality, as well as those that were stored in violation of the conditions or expiration date.

However, the ghostly second line, it is possible, may also be a figment of the imagination of the woman conducting the test. As a positive result, only the appearance of a clear, well-visible second strip can be taken, which appears along the entire length and width in the same color as the first control strip.

So, in order to obtain reliable pregnancy test results, it is necessary to conduct a home “pregnancy test” according to the rules, use proven quality tests and repeat testing after 2-3 days (at least once). And yet remember that false negative results are much more common. If the test clearly shows pregnancy, then it is very likely that you can be congratulated!

Especially for - Ekaterina Vlasenko