Regulations 

Why does pregnancy test indicate a negative result? What is a false negative pregnancy test

Girls-I want! Read the whole article! It seems to me that for each she will make a lot of clarity! Recently, she helped me very much)))))))))))))))

Pregnancy tests. Causes of changes in the level of hCG.

The action of the test for the definition of early pregnancy is based on the determination of a specific pregnancy hormone - chorionic gonadotropin (HCG), which begins to be produced in 1 day after implantation (attachment) of the fertilized egg to the uterine wall.

How is the conception?

The ripening of the egg and its exit from the ovary (ovulation) occurs approximately 14 days before the start of menstruation at a 28-day menstrual cycle.

Fertilization of this egg is possible for about 3 to 4 days. According to various authors, the dates of fertilization can be from 12 to 24 hours to 7 days. The survival rate of sperm in the female genital tract depends largely on the properties of the seed fluid. The mobility of spermatozoa is preserved longer than their ability to fertilize.

After fertilization, the egg is moving in the uterine tube into the uterus cavity. Transportation of the embryo towards the uterus continues within 5 - 6 days. Having reached the uterine cavity, the fertilized egg for some time is in a free state and on the 6th - 7th day of the intrauterine period is attached ("sticks") to the epithelium of the endometrium, after which it begins to actively embed into the mucous membrane (implanted).

From this point on, a pregnancy begins to develop, which reflects the production of pregnancy hormone - chorionic gonadotropin. Thus, a few days before the expected menstruation, the HCG traces appear in the body, which can be determined in the urine by home methods from the 1st day of the menstruation delay.

In medical institutions, the HCG is determined in the blood, detecting pregnancy a few days before the period of expected menstruation, because The sensitivity of the "blood" method is much higher.

Normal level of hCG in blood serum (honey / ml):

Healthy non-empty 0 - 15

Pregnant

1 - 2 weeks 19 - 145

2 - 3 weeks 111 - 3 640

3 - 4 weeks 1 090 - 17 600

4 - 5 weeks 2 740 - 59 600

5 - 6 weeks 23 500 - 137 000

6 - 7 weeks 29 900 - 222 000

7 - 8 weeks 30 500 - 266,000

8 - 9 weeks 54 700 - 268 000

9 - 10 weeks 25 900 - 234 000

10 - 11 weeks 46 200 - 238 000

11 - 18 weeks 16 500 - 92 700

18 - ... week 8 540 - 58,500

Attention! In various laboratories, the norms may differ.

Mechanism "work" pregnancy test

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

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

The test strip contains a conjugate (fragile compound) of antibodies to hCG with dye. When the sample of urine is moving along the absorbent strip, the conjugate is associated with HCG and forms a complex of an antigen antibody. In the zone of the positive reaction ("pregnant strip"), the complex is associated with anti-hgchantyl. At the same time, the dye is released and the red-pink strip is formed. If there is no hCG in the sample, no strip is understandable, not formed. In the meantime, urine moves on, the zone of a positive reaction passes and reaches the negative reaction zone ("test strip"). There, an unrelated conjugate antibody-dye binds to the reagents of the control strip, the dye is released and the second (control) strip is formed by the same red-pink color. All reactions occur within 3-5, less often 7 minutes.

In not too high-quality tests, the dye can be split off from the conjugate earlier than the entire complex of the antibody-HGC-Krasyser reaches the reaction zones, forming blurry spots. They are most often accepted for "false-positive" result. These false positive results are much less common and caused by quite specific reasons. Also a weak second strip can manifest themselves if "reappear" test, i.e. read readings not through the package 5 minutes, and later. Such a line occurs as a result of evaporation of water from the surface of the test, from which the conjugates are destroyed and the dye is released. So do not wait 10 min instead of 5, to "make sure".

Because it may not be any woman, doctors, especially old quenching correctly and correctly interpret the test results may not be inclined to trust tests.

What determines the pregnancy test?

A pregnancy test determines the human chorionic gonadotropin (HCG) - a hormone highlighted by the pocent from the moment of implantation of the embryo into the uterus wall throughout the pregnancy. The accuracy of this test is very high - no placenta, no xg. HCG can be determined both in the blood (in the laboratory) and in the urine (in the laboratory and at home)

What day after ovulation can be carried out test?

In principle, a positive result can be obtained already on the 7th day after ovulation. The embryo implantation needs 6-12 days, usually about 10 days. So it makes sense to wait 10-12 days after ovulation, but even in this case there are often false-negative results (that is, the pregnancy is, but the test is negative).

Tests of different manufacturers have different sensitivity, most of them are designed for use from the 1st day of the delay of menstruation. In 90% ± 5% of cases by this time, the embryo is already implanted into the uterus wall and begins to produce HCG. However, in 10% of cases implanting has not yet happened. Upon delay in 1 week, implantation occurs already in 97% ± 3% of cases. However, in practice, the accuracy of tests is limited to their sensitivity, so that real accuracy is somewhat lower. Since the HCG level doubles every 2-3 days, it follows the recommendation: with a negative result, if the menstruation does not begin, repeat the test in a few days.

What do false positive and false-negative test results?

The false positive result is when the test shows two strips in the absence of pregnancy. It happens when a woman takes preparations containing hCG, as well as in trophoblastic tumors. After spontaneous miscarriage or abortion in the early periods or removal of ectopic pregnancy, the HCG remains in the body for some time, and the test gives false positive results (that is, the pregnancy is no longer, and the test is still positive). As in the case of taking drugs containing hCG, two quantitative definitions of hCG with an interval of 2-3 days should be made to obtain reliable results. Reducing the level of hCG indicates that there is no longer pregnancy. Thus, false positive results are relative rarity, in contrast to false negative. The latter are obtained when the term of pregnancy is still too small and the level of hCG is too low to find it a test (or the test itself is not sufficiently sensitive).

The accuracy of the home test depends on various reasons:

  • The quality of the test itself. Products of different firms can vary significantly.
  • The shelf life of the test, the conditions and place of its storage. It is believed that in most cases the test can be trusted, provided that it is purchased at the pharmacy.
  • State of pregnancy. When pregnancy, which is on the verge of miscarriage, XG will be produced much less than with a normally developing pregnancy.
  • Conditions of testing: The study must be carried out using the morning portion of urine, in which the maximum content of the hormone is observed; The test estimate must be carried out by holding the time interval specified in the instructions.
  • Additional circumstances. The content of XG in the urine affects the diet and the functional state of your kidneys.
  • If you drank a lot of liquid on the eve of the evening or ate watermelon, or take diuretics (diuretics), the concentration of hormones in the urine will be too low, and the test "will not notice".
  • If you have a protein in the urine (even if you know anything about it) - the test can give an incorrect result.
  • If you were injected with hCG with the aim of induction of ovulation (drugs, pregnant) or to maintain the lutein phase, the traces of this hormone can remain in your body within 10 days after the last reception of the drug, and, accordingly, a pregnancy test can give a false positive result.
  • Also, the level of hCG can be determined several weeks after normal genera, cesarean sections, spontaneous or medical abortion and in other cases mentioned above.

As a result, it is possible to obtain incorrect information, and in both directions: no pregnancy, but the test seems to be positive. Or: there is a pregnancy, but the test is still negative. Both are a source of big experiences.

Patience you are good and huge good luck)))))))

If the pair "works" over the conception of the child, each test is a holiday and hope. It happens that menstruation is missing, but the test does not show 2 strips, then the woman thinks that they are just some kind of "these days." Waiting for another week-second, but menstruation never starts. Naturally, attend a gynecologist who confirms that it is pregnant! But, as is it possible, the pregnancy test was negative? Next, about this and talk.

What is a false negative pregnancy test?

You are pregnant, but the home test showed a negative result. This is called a false negative pregnancy test.

What are the reasons for a false negative pregnancy test?

The test determines the level of hong hong in the urine, and then shows either 1 strip, or 2. But there are cases when the test cannot determine.

Instruction

Each test, purchased in the pharmacy, has an instruction in which it is indicated how to test the test and how much to wait to see the result. It is necessary to read carefully and adhere to all the items described. If the instructions indicate that the test must be done in the morning, then you need to do in the morning, since it is at this time that the urine is concentrated and there is a chance to get a clearer result. There are tests that can be done during the day, and in the evening. Feel free to ask questions to the pharmacist.

Too early testing

One of the common mistakes that women make is the passage of pregnancy test too early. At an early stage of pregnancy, the hong hong level remains very low, so it can remain unnoticed in the test. Even blood test may not give an accurate result at an early stage.

It may also be that you simply missed an early positive result: the concentration of HCG across nine -one-ten days after ovulation is about 10 MME / ml. Nevertheless, it increases at a speed of 50% per day as pregnancy progressing and reaches approximately 100,000 MME / ml by the end of the tenth of the week. It then reduces and remains stable - 20,000 MME / ml.

Test set sensitivity

Some tests are so sensitive that they can determine the level of hCG of all over 20 MME / ml. However, some may detect only if the level is 50 MME / ml or more. So, if your test kit is low sensitive, you may not get an accurate result.

The shelf life of pregnancy test

Before buying, check the date of the expiration date of the pregnancy test. The expired shelf life will lead to false-negative results.

Medicine

Change the test indicators can also receive drugs, such as allergies or anticonvulsant drugs, for example, with epilepsy, as well as diuretics.

Ectopic pregnancy

When the fruit is in the uterine tube, and not in the uterus, then this means that an ectopic pregnancy occurred, in which a false negative test or the second strip can also be barely noticeable.

What if menstruation is missing and test negative?

Contact gynecologist! Blood test or ultrasound scanning (in later weeks) can give you a clear picture. In any case, the lack of menstruation without pregnancy is the reason for visiting the gynecologist. Perhaps the reason is strong stress that took place in life or in improper nutrition.

Repeat the test in a week. If your first test has been negative, and your menstruation has not started even a week after the test, repeat the test. The gap in seven days will increase the level of hCG.

Among all pregnancy tests Evitest.In my opinion, is the most reliable. It was he who still confirmed that soon I would become a mom for the second time, while the test of another manufacturer was simply silent.

Each time making a pregnancy test, any woman with a fading heart peering into that section of this small cardboard stick, where two cherished stripes should appear. Or should not appear. Not for all women, pregnancy detection is the performance of cherished desire and great joy.

I started dreaming about the age of 25, when the study was almost finished, I looked down pretty decent work, I paid off with all the debts, including mortgage, that is, my life was stable, equipped, and I was ready for To ensure that a little man entered her, who would call me mom. I really wanted a child! I envy looked at my friendships, who are already married, who has already had kids or a rounded tummy. The girls have long forgotten the institutes, walked around the cafes and various events, where they met their satellites of life. At that time, I only studied and worked, I had a lot of problems that had to solve myself, there was no one to rely on anyone, respectively I was not to the feels.

But one day a man appeared in my life with whom we had a lot of common interests and who could be a good father to my child. We met for two years, and all this time he told about how to have a big friendly family, three children, a good apartment, a cat and a dog. But only told, not offering anything. And I've been waiting for everything, I began to hint that as if we were already decently so years, and it seems to be well known to each other, it's not time to legalize our relationship.

And then he seemed to first realize that everything really goes to ensure that we became families, men somehow come to the realization of this. We began to live together, prepare for the wedding and plan a child.

In one day I clearly realized that in the body somehow everything was not as before. Frequent urge to the toilet is small, and painless, it doesn't seem to be cystitis. Some weakness and lethargy, similar to ORVI, even a small rise temperature was observed. Began to beat your chest, as if before the month and there was a feeling that there was something heavy in the bottom of the belly, all the time somehow wanted to sit down.

I began to suspect that someone settled inside me, finding on the Internet that all these signs in the complex may indicate the originating pregnancy. But to believe it was afraid, despite the fact that I wanted it for a long time. Several days have passed, these symptoms are not going anywhere, but they became even more pronounced, but to tell someone whoever, even her husband, was scary.

At work, I shared my suspicions with one girl from the separation of laboratory diagnostics and received a proposal, which was simply not able to refuse. On the same day, I passed the blood test on the HCG and already on the 9th day after conception, I knew that I would have a baby.

No pregnancy test, as well as ultrasound, does not yet show the presence of a fetal egg on such timing, the tests are struggling later, when the level of the corresponding hormone in the blood reaches such a level that the hormone begins to stand out with urine. And then he discovers it. Ultrasound Detects the embryo even later.

Having learned that I was pregnant, excitement and concerns I only added. Is this pregnancy uterine, reliably defeated the embryo in the endometrium, whether it develops and whether all the organs and systems have laid out.

Not doterpets before the first day of delay, I bought one of the most popular EVITEST pregnancy tests on the same day, for consistent with double, in a few days to double the first result, whatever it is.

The next day I decided on the morning, although I will say honestly, to do a pregnancy test is very scary, regardless of what result you expect!

A few minutes later, a pale strip appeared on my dough, barely noticeable, but so long-awaited! Until the day of the alleged delay there were still four days, and the baby had already shown me his presence.

A day later I made a retest, and the strip was already clearly noticeable, which could only mean one thing - the level of hormone in the blood is growing, which means the pregnancy is developing.


However, in order to make sure I passed it again in a few days. blood on hCGIn the analyzes there was a significant increase that, in principle, it was confirmed that the pregnancy was uterine and proceeds normally.

On the 8th weeks, I unequivocally confirmed that I would soon become a mother that pregnancy develops correctly, everything is in order with the baby. Husband, learning that he would soon be a dad, he was somewhat discouraged, he did not expect that it would happen so quickly, thought that it would take several years to get pregnant.

Further everything proceeded by myself. Toxicosis since the 6th week and before the end of the 13th, planned ultrasound in every trimester, analyzes, visiting consultation, the best vitamins, conducting weight gain and salt use, unexpectedly arising sharp cholecystitis, a terrible heartburn in the last period of pregnancy and completely unexpected for me.

Despite the fact that the daughter got it hard for me, I almost ruined the child, I was immensely happy that I finally became a mom of this long-awaited girl. However, I couldn't have any speech about re-pregnancy, I did not want to risk my life, and I didn't have the right to it. For myself, I concluded that my body does not know how to give birth.

The first year of the child's life was hard, her daughter had a lot of sleep, I slept badly, we often went on doctors due to the problems with the health that had a child as a result. Closer to the year, everything was normalized, we went to the summer to relax to the grandmother, I have already started having fun from the process of raising a child, my husband sighed with relief that you can now sleep well at night.

A year and 3 months I finished feeding the baby with breasts, because the daughter stopped showing interest in breast milk. True had to resort to medication support. And at about the same time found that the next periods did not come.

There were no special feelings, because I already knew how my pregnancy begins, I didn't really like it, I didn't even hold it on acclimatization. Just in case I bought pregnancy test Another company, Frautest, and not EVITEST, did it, but he was negative. Therefore, I calmed down and began to wait when they come.

A week later, the critical days did not start, but began to hide closer in the late afternoon. Suspecting something wrong, I went to the pharmacy for already verified by me for a pregnancy test EVITESTbecause last time he did not let me detected pregnancy before the delay, despite the fact that his sensitivity is 20 MME / ml, and Frautest - 15 MME / ml, That is, in theory, he is more sensitive and must identify pregnancy earlier. Its cost then and now it is about 50-60 rubles, but I trust him much more than tests for 10-12 rubles, and I do not see the point of buying tests for 200-300, the essence of the analysis itself does not change.


Double EVITEST I was already taken, I took the usual, single, it differs only by the fact that in the package there is one test strip, and not two. Just in case grabbed the double FrautestTo check more than once with tests of different firms. I still hoped for nothing and tests would confirm the first result. Give birth to my plans was not included. But it was not there. In the next morning, observing all the rules for conducting a pregnancy test I found on it 2 clear stripes. Two! What could only mean one thing - I'm waiting for a child again.


My body has not yet had time to relax, adapt, gain strength for re-pregnancy. He was experiencing extreme loads in the form of pregnancy and breastfeeding, And then on, please! I instantly remembered my toxicosis, my sleepless nights when I chuckled with bile and acid, and I had to sleep in a half-day position to reduce the manifestations of heartburn. I was not ready for such a turn of events.

It remained hope that the test I got a false positive.

Causes of false positive pregnancy test:

- States that are not associated with pregnancy, but characterized by the increase in hCG:

  • hCG tumors (bubble skid, chorion-epithelity of the uterus, etc.);
  • recently ending pregnancy (condition after miscarriage, abortion or removal of ectopic pregnancy);
  • reception of medical preparations containing chorionic gonadotropin.

- Low test quality or expired shelf life.

- Subjective factors.

An option associated with an increase in the level of hCG in the body disappeared immediately. The second option I could not exclude, although, judging by the date of the test, it was fresh. Subjective factors include, for example, only the visual appearance of the second strip, which is actually not really. It happens because of the excessive desire of a woman to have a child. There is no real strip, but the brain of women processes information from the visual analyzer so that it sees two stripes. I did not have such an incredible desire to become a mom for the second time, so the third option also exclude.

To testify the test to be truthful, it must be carried out strictly following the instructions that are attached to the test.


It is necessary to perform the test in the morning hours, immediately after awakening, when the hormone concentration in the urine is maximum. However, if necessary, the test can be performed at any time of the day. The test must be taken in hand only from the side. Plastic coated. The work part for which the reagent is applied, the hands are not recommended for the hands, since the dyed-fat traces can distort the test results.

Biomaterial (that is, urine) it is necessary to collect in a clean container to minimize the possibility of obtaining a false result. The test in the vertical position must be omitted into the liquid to the level specified by the arrows by 5-10 seconds, until the working part is completely impregnated.

With the correct execution and suitability of the test to use, one bar appears, which is the control pointing to the fact that the test is carried out correctly. Her appearance does not mean pregnancy. But if there is a second strip closer to the plastic end of the dough, that is, a serious reason to suspect that there is a pregnancy. It is necessary to estimate the result in 5-7 minutes.

But even a positive pregnancy test is not a 100% guarantee of its presence. It will just confirm or disprove pregnancy can only doctor.

In addition to the false positive result, in some cases, a false-negative result can also be observed, in which the test does not show anything, and there is a pregnancy.

Causes of a false negative pregnancy test:

  • an early study period in the event that the concentration of hCG in the urine did not reach the required level;
  • excessive use of fluid, which leads to severe urine dilution;
  • diseases that prevent the removal of hCG with urine (renal pathology, some diseases of the cardiovascular system).

Insofar as Frautesti had a double, after a few days I made a test again, and this time he still showed two strips. In this case, the sensitivity of the tests in the box with one thing and with two absolutely the same one.

But I already knew that pregnant, toxicosis this time began a week earlier than in the first pregnancy. I.e Frautest It worked only when the level of "pregnancy hormone" was quite high. Evitest. Still, it turned out to be more sensitive and accurate.

I did not have a special joy, honestly. But then I could not imagine how much it would be difficult for me to wear a pregnancy, and then bring up two kids with such a small difference in age. Now, looking at your younger child, which is just at the age of the day, in which there was a daughter, when I got pregnant, I just grab my head and think where my brains were! I certainly wanted a second child, but not as fast as it happened.

When the 8th week of pregnancy came, and the opportunity to do ultrasound appeared to clarify how the baby develops, I realized that all thoughts are material. My reluctance to preserve and enter this pregnancy led to the fact that during the ultrasound, the detachment of the fetal egg was found.


But his heart beat him.


I was in the so-called state of miscarriage. At the same time, I did not have any specific sensations. Neither pain in the bottom of the abdomen nor blood survey. A few days later, the pregnancy could end.


He tuned with the results of ultrasound to his gynecologist, I received her recommendations for saving. But in fact, I could not do that, simply because I had no one to leave a daughter. I refused to comply with the hospitalization, promising a doctor to observe the bed and accept the "Dufeston" to preserve pregnancy.

I think many women will agree that the pregnancy test should be attributed to the greatest or at least the most useful and convenient inventions of humanity. After all, only a dollar-two, a few minutes - and almost anywhere and at any time you can get an answer to your concern you question: you are pregnant or not. Could our grandmothers dream of such a dream?!

In general, it is undoubtedly a thing! However, it has one essential drawback: often shows an erroneous result. And in the overwhelming majority of cases, it is false-negative - when, with the actual pregnancy of pregnancy, the test shows its absence. What could be the causes?

Very previous testing

Usually, by the first day of the delay produced by Horion, it is already increasing enough to fix the test reagent. In some cases, this is possible a little earlier, in others - later. But still in the overwhelming majority - only by the beginning of the estimated periods. Therefore, in you meet the recommendation to test only after the delay of menstruation and repeat it in a few days - for higher accuracy. If the level of hCG in the urine at the time of testing is not yet quite high (less than 20-25th / l), then you will get a false negative result.

Too diluted urine

The accuracy of the pregnancy test in the early deadlines is higher than the more concentrated urine is used for testing. Therefore, pharmacists are recommended to conduct it in the morning with the first portion of the urine - overnight its concentration increases, and there are more chances that the jet strip "Write" hCG. If you are taking diuretic drugs, which forces you to urinate even at night, or before testing you drank too much fluid, then you shouldn't even hope to rely on the morning urine.

At the later deadlines, the level of gonadotropin in the urine is already increasing that the test shows a truthful result regardless of its time. But if only 12-14 days passed since the conception, this condition plays a big role in obtaining truthful results.

Violation of rules

These and other mandatory rules and conditions for conducting non-sales tests are described in each instruction. Because only when they comply, you can count on a reliable result. If you have broken any of them, then the test may well be false-negative. Check out the manual and act strictly according to the instructions.

Non-quality test

Almost all modern pregnancy tests are characterized by rather high reliability, but it is still not excluded that you caught a low-quality, shivering or spoiled test, which was stored in violating conditions. A re-conducted test after a few days will ensure the informativeness of this method.

Pathological pregnancy

Unfortunately, among the causes of a false-negative test, there may be tragic - this is a frozen (undevelopable) pregnancy or an embryonium, in which HCG does not increase, as usual happens with normally developing fruit. Sometimes hCG is produced in insufficient quantity in the threat of miscarriage in the earliest period, and then the result may also be false negative. The results are capable of influencing the work of the kidneys.

Therefore, if a repeated pregnancy test shows a negative result, but the next periods never occur, you should definitely contact the gynecologist to determine the cause.

Especially for - Elena Kichak

For each woman, the delay of menstruation is a source of excitement and stress. Related pregnancy or not, the woman at the very first signs wants to quickly dispel doubt. Fortunately, today you do not need to wait a few weeks or months to learn the truth about your condition. Special tests sold in each pharmacy will show the result within a few minutes. The incredible popularity of this invention is explained by the simplicity and convenience of use: a test for pregnancy can be done anywhere and at any time. It does not require special training and professional knowledge.

However, how reliable results are, and can they always trust? According to experts, the permissible degree of error is 1-5%. However, in practice, erroneous results are much more common. It turns out rarely. In the overwhelming majority of cases, an abnormal result is false negative. Why does this happen? In fact, the factors causing this error, quite a lot. And in order to establish the true cause of violation and avoid serious pathologies, you should consult a doctor.

The action of the test is based on detection in the urine of a woman of the chorionic gonadotropin of a person - a special hormone generated in the body with the onset of pregnancy. At the same time, the blood hormone is found in the earliest period - a week after conception, and in the urine - 10-14 days later.

Use the test is quite simple. It is enough to place it for a few minutes in a container with morning urine to a certain level. The indicator for most tests are strips manifested in urine influence. The appearance of one strip says that there is no pregnancy. This is a control indicator. It suggests that the test is suitable. Two manifesive strips talk about pregnancy. And the higher the level of hCG, the brighter the strips are expressed.

Causes of negative test with pregnancy

Pregnancy tests are extremely simplicable in use. Nevertheless, some circumstances have a direct impact on the result. The false-negative test may be provoked by several reasons.

Quality test

The most banal cause of a false negative result is the use of poor quality test. These can be overdue or in unsuitable storage conditions tests. Therefore, when applying tests, it is necessary to act on the principle of "trust, but check." A few days later, you need to repeat testing using the products of another manufacturer. If doubt remained, then you need to immediately consult a doctor.

Incorrect use of test

Before applying the test, you must carefully read the attached instructions. There are several types of tests that differ in the method of application and in sensitivity indicators. In most cases, if all the rules are followed, a reliable result is issued.

Early testing time

The most common reason for issuing an inaccurate result is the impatience of a woman. The fact is that in the early periods of pregnancy, the production of hCG can occur pretty sluggish. At the same time, the hormone first penetrates blood and only a few days later - in the urine. Therefore, in the first week after conception, its concentration in the urine may be insufficient to detect with the help of the test. Regardless of the manufacturer, price or advertising product, which was performed first check, 5-6 days later, it is recommended to re-test.

Reception of diuretic drugs and non-compliance with testing rules

Most tests are designed for a fairly high concentration of hCG in the urine. Reception of diuretic drugs, a large amount of liquid or products that cause enhanced removal of fluid from the body leads to the fact that urine becomes diluted, and the hormone concentration is reduced to the level undefined using tests.

Therefore, on the eve of the procedure, refuse to receive any products that can affect the reliability of the result. Testing is carried out only with morning urine, when the level of hCG in it is highest, and its viscosity contributes to the successful audit. If for some reason testing can not be made immediately, the portion of the assembled urine should be stored in the refrigerator not more than 48 hours.

Pathology of the excretory system

Some pathology of the excretory system can also cause a false negative result. Inflammatory processes in urinary organs, renal failure lead to disorders of the renal filtering ability. Mechanical exchange products, including hCG, are delayed in the blood and are not displayed in the urine. Other pathologies, for example, heart failure, atherosclerosis, arterial hypertension, lead to impaired renal filtering.

Various infectious or tumor processes, as well as epilepsy or brain concussion lead to the appearance of protein in the urine, which may disguise the presence of a pregnancy hormone.

Reception of hormonal drugs

A blurred picture of the test can be obtained against the background of hormonal therapy. Preparations change the normal ratio of hormones in the body, which can hide the true state of affairs.

The presence of pathological pregnancy

The test may issue a negative response in violations that have arisen after conception. So, with an ectopic pregnancy, the level of hCG in the blood is growing slower than at a normal process, to which the test reacts very weakly and can show a barely expressed second strip or the absence of such. Therefore, if such signs like the latency of menstruation, the loading of the mammary glands, the emotional differences are combined with a negative test, then this is a serious reason to urgently turn to the gynecologist.

Such anomalies of the development of pregnancy, as a frozen fruit, weak attachment of the fetal egg to the uterus wall or chronic placental fetal failure are also causes of a negative test. Thus, a negative answer is a formidable sign of an approaching miscarriage or already interrupted pregnancy.

Are there pharmacy tests after Eco?

With the help of tests, you can identify pregnancy regardless of whether it has a natural way or due to extracorporeal fertilization. The presence of a fertilized egg in the body of a fertilized egg always leads to the development of hCG, and the introduction of the embryo into the wall of the uterus is the cause of an increase in the hormone concentration to the level that allows you to identify pregnancy using tests.

The only condition for obtaining a reliable result is timely testing. With eco, testing is recommended not earlier than the 14th day after the eggsset. Prior to this period, the likelihood of a false negative response is high. If the process of implantation of the fertilized egg has passed successfully, then starting from the 15th day the tests provide a pronounced positive result.

Types of tests

As already mentioned, non-compliance with the instructions when applying the test leads to a false negative response. To date, there are several types of tests, each of which requires a special approach. Tests differ in the method of application, as well as by the degree of sensitivity to the hormone.

According to the method of application distinguish:

  • Strip tests or strips

These are the most common and affordable first-generation tests. To obtain the result, the strip is necessary for a few seconds to dip in the pre-assembled morning portion of urine. Their disadvantage is a high degree of error and a small sensitivity to a hormone highlighted by chorion.

  • Tablet test

By sensitivity, he surpasses ordinary strips. The indicator is enclosed in a plastic box with two windows. One-time pipette coming in a set, a drop of urine is applied in the first window. After a few minutes, the result appears in the second window. From different manufacturers, it can be expressed in different ways: "-" or "no".

  • Inkjet test

This is a third and more improved generation of pregnancy tests. It has a high sensitivity and can identify the presence of even a minor concentration of hCG. The advantage of the test is that urine does not need to be collected in a separate container. Therefore, it is convenient to apply in any conditions. Pretty receiving end to put under the stream of urine, the result will be ready in a few minutes. In addition, the inkjet test is able to identify hCG even in diluted urine. Therefore, it is not necessary to test in the morning.

  • Electronic test

A digital test, working with an accuracy of 99% from the first day of the expected cycle. It has high sensitivity, so it can be used at any time of the day. The result is issued on the LCD screen "+" or "-" or the symbols "Pregnant" or "Not Pregnant", which means respectively the presence or absence of pregnancy. The disadvantage of electronic tests is their high price.

The test sensitivity is indicated on the package and in the instructions. According to the degree of sensitivity, tests are distinguished that perceive the following hormone concentrations:

  • 10 MME / ML;
  • 15 MME / ML;
  • 20 MME / ML;
  • 25 MME / ML;
  • 30 MME / ML.

The degree of their sensitivity increases with the improvement of tests. Thus, strip tests react only to elevated CGC concentrations - 20 MME / ML and higher. For tablet devices, this indicator is 15 MME / ML. And the sensitivity of inkjet and electronic models is highest: they give the result at 10 MME / ML.

How to choose a test to avoid a false negative result?

To get the most reliable result, you need to be based on the intended date of conception. If the need for testing occurred after a latency of menstruation, then lay out a round sum on the ultra-sensitive test simply does not make sense, because at this stage, if pregnancy, the level of hCG is already so high that it is easily determined using conventional test strips.
If, before the start of menstruation, there are a few more days, and you want to learn about your condition today, you will have to fork out for a highly sensitive inkjet or electronic test.

Does tests lie?

Answer