Do not lie to me! Can pregnancy tests be wrong? Pregnancy test: instructions for use. When a pregnancy test shows correct results
Many doctors use rapid tests, recognizing the results as reliably correct. They are taken into account when planning further, more accurate diagnosis. They help on early stages find out that a woman is expecting maternity leave. But can a pregnancy test be wrong in the early stages?
Why does the test not show pregnancy in the first weeks after fertilization of the egg?
You need to understand that the principle of operation of this device is the reaction of a special reagent to human chorionic gonadotropin human (hCG). In the absence of pregnancy hCG indicator at zero or at minimum quantities. In a pregnant woman, the hCG level begins to rise rapidly, as it is produced by the chorion (the membrane of the embryo).
If your period is late and a woman suspects that she has conceived, she buys a test. He must react to hCG level in urine. But not every girl knows that the level of this hormone first increases in the blood, and only on days 14-16 in the urine. In the first days after the delay, the probability of error is very high, since it may not yet appear in sufficient quantities.
Most tests are accurate starting at a concentration of 25 units.
In this table you can see what the content of hCG is in the urine by day from conception.
False negative result
If a woman is sure that conception has occurred, but the test is false, then the procedure must be repeated after 3-4 days. If nothing is found again, then you should consult a gynecologist and undergo an examination.
False negative result possible for the following diseases:
- ovarian dysfunction;
- regular intake hormonal drugs;
- failure of menstruation, in which it is not possible to count correctly exact date pregnancy;
- the presence of tumors of various types;
- with pathologies in the development of the embryo. Sometimes pregnancy negative test passes already with a frozen fetus;
- pathological changes in the kidneys.
False positive result
In what cases is a pregnancy test false positive?
- incorrect use of the test;
- expired pregnancy test;
- often the test shows 2 stripes within a month during an ectopic pregnancy, after spontaneous or induced abortion. In the early stages, women may have spontaneous miscarriage during her period, which she doesn't even know about. However, the test results may be positive;
- taking hormonal medications for the treatment of the genitourinary and reproductive systems;
- wrong hormonal background. Most often, such women have an irregular menstrual cycle, and their body weight may be significantly increased;
- two stripes may indicate menopause. Knowing that mistakes are possible during this period, women do not always rush to the gynecologist. However late pregnancy(after 45 years) is not that uncommon. Therefore, it is better to play it safe and go to the doctor;
- an erroneous value may occur if there is a cyst on the ovaries. It is the growth of tumor formations that is accompanied by an additional release of hCG into the blood.
What to do if a pregnancy test shows positive result, but fertilization could not have happened? You need to urgently go to the doctor, get examined and treat diseases that can provoke increase in hCG.
Other reasons for incorrect results
Do pregnancy tests lie for other reasons? Women often encounter a problem when the indicator does not show a single strip. This option is possible if it is of low quality. Therefore, you can test at once with several strips from different manufacturers.
Not all women read the instructions carefully. It says that the accuracy does not exceed 97-99%.
If the test is negative, but there is a delay, then the reason may be improper storage in the pharmacy or at home.
An error is possible if a woman purchased strips “in reserve.” Many people don’t even pay attention to the expiration date.
The test may give incorrect data if it is not immersed in urine correctly.
If a woman has an increased level of protein in her urine, then all the symptoms of pregnancy will be, but there may be no result. After all, the strip also has a protein base.
The result may be false negative or false positive if the woman is in severe stressful situation. Tests are often mistaken for those women who want to become a mother and cannot get pregnant for a long time.
How to use it correctly?
The test is informative from the first day of the delay and the further you go, the more accurate the result. If a woman is 5 days late, then it’s definitely time to go to the pharmacy.
Paper
The most inexpensive budget test is a paper strip. If there is a delay, you need to lower one end of the stick into the urine to the mark and hold for several seconds. After this, the strip is placed in a horizontal position for 1-3 minutes and wait for the results. Does the test always show pregnancy? The answer is no. There is a possibility of error (1-3%).
Tablet
A tablet test is more accurate and informative. Its operating principle is similar to that of paper, but it is housed in a plastic case. The information is quite accurate, error is possible only from misuse. Often such a test would lie if the procedure was carried out during the day or evening.
The correct result is guaranteed when using morning urine. If a woman wants to get pregnant, many gynecologists suggest using just such a gadget. It is convenient and quite accurate.
Jet
Co jet test there is no need to collect urine in a container. It is enough to place it under the stream and the result will appear within a few seconds. This test is ultra-sensitive and quite accurate.
Electronic
If a woman is 5 days or more late, doctors may recommend electronic test. If a positive or negative result is obtained, then such information is considered accurate, and the device has a maximum reliability indicator.
If a woman is sure that she is pregnant, but the paper test is wrong, then you can use a digital one. Its advantage is that it will not only show the occurrence of fertilization, but also the date of conception. This option can be used when your period is 7 days or more late.
What happens if there is an ectopic?
Unfortunately, the fertilized egg does not always enter the uterus. Because of pathological processes may start in the pipes ectopic pregnancy. How does the test react in this case?
Upon implementation ovum– it doesn’t matter whether it’s in the uterus or the fallopian tube – hCG is still synthesized. This means that the test will show that there is a pregnancy.
So, this gadget is quite accurate, but it can also make mistakes.
Competently: answers from a gynecologist
Obstetrician-gynecologist Elena Artemyeva answers patients’ questions.
— I had an ectopic pregnancy and a miscarriage. And now, three months later, there are again two stripes and a delay. Could there be a pregnancy?
— A pregnancy test may be wrong inflammatory processes, localized in the pelvis. I advise you to do an ultrasound and donate blood for hCG.
— I had a cryopreservation. What is the reliability of a pregnancy test now? The paper one showed a very weak second line, and the electronic one showed a plus sign and a period of 2 weeks. I take utrozhestan, chimes, and folic acid.
- Do a blood test for hCG, this is the most exact method. But in general, weakly positive is positive test! Continue taking your medications.
— Before my period, Evitest showed two lines, and then my period came. After my period I have two again, but the second one is weak. But the paper one showed only one... Maybe it was defective?
- Sometimes paper strips are stained not by hCG, but by other substances present in the urine. And they give false positives. A more accurate method is a blood test for hCG.
— Can thrush affect the test?
- No. Yeast vulvitis does not affect the result in any way. It is not thrush that is determined, but hCG.
— What result will the strip show if the pregnancy is ectopic?
— It shows pregnancy of any localization.
— What is the reliability of a pregnancy test before a delay?
- Low. He is informative from the first day of the delay. 2-4 days before menstruation you can donate blood for hCG.
— Period is 5 days late, the test is negative, could there be pregnancy?
- Probably not. At this time the result is quite accurate. But I still advise you to donate blood for hCG to exclude pregnancy. And then go to the doctor: you need to understand what is the reason for the cycle disruption.
— I had 2 stripes and a delay of 5 days, and then my period came. After menstruation there are two stripes again. What does it mean?
- This may be due to cycle disorders. You need to go to the doctor and get examined.
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Once upon a time, the only “tests” by which pregnancy was determined were observations. The first is menstruation, and not only a delay, but also a change in color and quantity. Second - quirks of taste: expectant mother may love sweet tea with herring, finding this combination an unsurpassed delicacy. Third, mood swings: hormonal changes turn a pregnant woman into an extremely unbalanced and nervous creature. Fourth - although a small, but pleasant increase in bust size.
However, the “swing” of mood and enlarged breasts may indicate a well-known premenstrual syndrome(PMS), and delays in menstruation - about hormonal disorders or gynecological diseases. Sometimes the symptoms of early pregnancy and PMS are as similar as two peas in a pod. The hormone progesterone, the maximum of which is present in a woman’s body at the end of each menstrual cycle and throughout pregnancy, is misleading. That is why the presence of at least one sign from the list is a reason to purchase a pregnancy test to confirm or refute your suspicions.
Human hormone
Pregnancy tests work on the same principle: they all detect the so-called human chorionic gonadotropin, also known as hCG. This substance appears in the body of a pregnant woman and is present in her blood and urine until birth. A chemical reagent that impregnates the test interacts with it. Minimum term pregnancy, which can be determined by “pharmacy” tests, is 14 days.
Three generations
There are three types of tests sold in pharmacies.
Test strip. A narrow piece of paper with an indicator must be lowered into a container with urine to a certain mark and for the time specified in the instructions. If you immerse it below the desired level or underexpose it, the indicator will not be sufficiently saturated and the test may give incorrect information. It costs mere trifles.
Tablets. They look like a box with two “windows”. First you need to drop a little urine for it to happen. chemical reaction, and the second will soon show the result. Tablet tests are more convenient to use than test strips, but they are more expensive.
Jet. The most modern. It is enough to place the “device” under a stream of urine - and in about five minutes you can find out the result. The appearance of an additional line will indicate whether you are pregnant or not. The test with “all the amenities” is the most expensive.
Easier or more difficult? Cheaper or more expensive? Doctors advise not to save money and choose according to the principle: the more expensive, the better. The fact is that such tests are equipped with the best reagents, and their methodology is simpler. Much depends on sensitivity. Tests marked 20 mIU/ml are able to recognize the “pregnancy hormone” in a lower concentration, and therefore will more accurately determine an earlier stage of pregnancy than, say, their “brothers” with a sensitivity of 10 mIU/ml.
Briefing
The expiration date is the first thing you need to pay attention to. After all, an expired reagent may not “notice” anything in a pregnant woman or detect a pregnancy that in fact is not in sight. Before testing, carefully study the instructions (by the way, if the product is imported, check whether a translation is attached to it). If you violate one of the points, the answer may be incorrect. The algorithm for reading test results from different brands is significantly different. In some tests, pregnancy will be indicated by a change in the color of the reagent, in others - by the appearance of an additional strip. But all of them are carried out in the morning on an empty stomach - it is at this time that there is a high concentration of human hormone in the urine.
Right on time
There is an opinion that pharmacy tests are able to recognize pregnancy almost a day after possible fertilization. Doctors competently declare that no one and nothing can determine pregnancy within one day. This is still in the realm of fantasy. No matter how much you would like to know the answer as early as possible, you will have to wait until the day your period starts. You can’t do it earlier, otherwise the test will show a negative result, although in fact you may be pregnant. It’s just that at that time the concentration of the hormone in the urine is still so tiny that even a supersensitive device is unable to detect it.
Attempt No.
Tests give an accurate answer in 98 percent of cases. True, another 2 percent remain... For example, if there is no pregnancy, but the test persistently shows the opposite, the problem may well lie in diseases of the ovaries, trophoblast (one of the serious ailments of the uterus).
To get an accurate result, gynecologists advise repeating the test three times with an interval of three to five days. If all the answers are positive, immediately go to the doctor. The fact is that tests only show the presence of pregnancy, but do not distinguish between uterine and ectopic.
Women are born with a certain supply of eggs, the consumption of which is controlled by nature itself! And only she knows why ovulation may not occur every month.
Alternative
If we talk about everyone existing methods determining early pregnancy, one cannot fail to mention the measurement method basal temperature. Read it, shudder and, as they say, feel the difference. If menstruation did not come on time, a regular medical thermometer had to be inserted into the rectum for five minutes immediately after waking up, without getting out of bed, for a week. If the temperature was constantly above 37 °C, the woman was suspected of being pregnant. In addition to the obvious inconveniences, this method was also not entirely accurate. For example, if there was a threat of miscarriage, the temperature could well be below thirty-seven.
Everything is covered in blood
The presence of human hormone can also be determined by a blood test in antenatal clinic. At one time, when pharmacy tests were not as accurate as modern ones, this was the control. Now it is being carried out to determine blood counts and monitor the progress of pregnancy. For example, when normal pregnancy the level of another hormone - trophoblastic beta globulin - should increase. If its concentration is below normal, the doctor will immediately take action: this may indicate an ectopic or frozen pregnancy.
Video
If the tests tell you about pregnancy on the first day of the delay, then the ultrasound machine is able to distinguish it only on the 5-6th day. However, determining the deadline is far from its main task. The purpose of ultrasound is to detect ectopic pregnancy or fetal malformations as early as possible. It is advisable to carry out the procedure three weeks after the expected conception, not earlier. Doctors recommend being “tested” not with a traditional “iron”, but with a more sensitive vaginal sensor, which is inserted into the vagina. However, hurry up - this must be done no later than 12 weeks of pregnancy.
Test + contraceptive
Previously, women tried to calculate the days of ovulation, that is, the most favorable days for conception. But still, the accuracy of the “calendar method” left much to be desired. And what kind of accuracy can we talk about if women are born with a certain supply of eggs, the consumption of which is controlled by nature itself! And only she knows why ovulation may not occur every month. This was the case until a test for determining ovulation appeared - a contraceptive and a pregnancy test in one set. With its help, you can calculate both the days of safe sex and the period most favorable for conception.
A woman using this device does not need to take hormonal contraception. Based on the composition of urine, it determines the days on which it is recommended to take special precautions and periods when the possibility of fertilization is minimal. By detecting luteinizing hormone in the urine - a signal for ovulation - the test suggests the days when pregnancy is most likely to occur. By the way, if not a single ovulation is recorded within three months, this is serious reason consult a gynecologist: the functioning of the ovaries is impaired and treatment is required.
If you are in doubt about the reason for the absence of menstruation (delayed menstruation), you can always use home test for pregnancy to confirm your guesses. Most women feel comfortable using them because it is the most quick way determine whether the delay is caused by pregnancy, and only you know the answer. To obtain accurate results, it is important to use the test correctly - in right time and according to the instructions. You also need to make sure that you do not use a pregnancy test that has expired. Many women ask whether the test can show the correct result after the end date of use indicated on the package?
Can you trust an expired pregnancy test?
The answer is simple, like all other products, a pregnancy test has an expiration date, after which you should not hope for its reliability.
If you happen to be pregnant but have previously tested your urine with a pregnancy test and received a negative result, it can be assumed that it was damaged or invalid. You may not realize that you were using an expired product.
There are many on the market today various tests for pregnancy and they have different terms suitability. After production, most of them are usable for about two years. Cheaper products usually have more short term storage Therefore, it is better to buy pregnancy tests that were made just a few months ago.
Why does the test expire?
The reason is that they use a special Chemical substance, which reacts in the urine. After a while it becomes ineffective, which makes the tests useless and unreliable. You should pay attention to the packaging and check the production date and expiration date before purchasing, which also needs to be taken into account when using them. Understand that you cannot fully trust the results if you use a test in June that already expired in May.
What is the expiration date for more expensive and sensitive tests?
Tests to determine pregnancy at the earliest stages are more expensive and have high level sensitivity because they must detect hCG hormone in small quantities. Due to their high sensitivity, they can report pregnancy even a few days before the delay. Despite all this, their shelf life is the same as that of simpler samples - usually 24 months.
Can expired tests be used?
It is very likely that you will still be able to get a correct result with a test that is several months out of date, especially if the storage conditions have been followed. However, not in all cases. These tests will not be as reliable, which is why manufacturers recommend against using them.
To avoid getting false positive or false negative results, you need to pay attention to the end date of the product before purchasing it. You should keep in mind that the dates on the box and the test itself may sometimes differ. You need to focus on the one that comes first.
Additional FAQs
What is the difference between an HCG blood test and home pregnancy tests?
In both options, the presence of human chorionic gonadotropin (hCG) is checked. Home pregnancy tests detect this "pregnancy hormone" in your urine and do not require any special skills on your part. Blood tests are usually more expensive and are not necessary if you have tested for hCG in your urine several times and they give the same result. Home tests are usually most effective a few weeks after ovulation (a few days after the missed period), but more sensitive options are now available to detect pregnancy earlier, although with less confidence in the result.
How to carry out the procedure?
Home tests are easy to use. You just need to hold it under a stream of urine and wait a few minutes until the plus/second line symbol appears. If this happens, you are pregnant. Some pregnancy tests require you to collect urine in a container and dip a test strip into it.
Modern tests usually, in addition to the test strip showing the pregnancy itself, have another one, which is called a control one. This control indicator indicates whether the device has worked correctly. Therefore, if an expired pregnancy test has a well-developed control line, then it is more likely that he did not lie.
It is believed that it is better to use the first morning urine for a more correct result.
How accurate are home pregnancy tests?
They are generally very accurate, but this can be influenced by many factors, including the correctness and timing of the test, and the brand of the test.
When should you get a pregnancy test after a missed period?
Many home tests claim to be 99% accurate when used starting on the day you expect your period (the day you're due). Research shows that it is best to wait at least a week after the delay to get the most accurate results.
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Nowadays, you can purchase relatively inexpensive tests in pharmacies that allow you to quickly diagnose pregnancy at home. All such tests are based on detection in urine specific hormone - human chorionic gonadotropin (hCG). This hormone begins to be produced female body during pregnancy, namely: one day after implantation (attachment) of a fertilized egg to the wall of the uterus, which approximately corresponds to one week after conception. The test detects pregnancy in the first days after a missed period, that is detects pregnancy of at least 14 days.
It often happens that when a woman, after taking a pregnancy test, sees cherished two stripes, she doesn’t believe her eyes, begins to doubt the veracity of the test, buys several tests from other manufacturers just in case... Does this make sense? Can the test be wrong?
Answer: yes, it can. Although the likelihood of such an error correct use very low: the accuracy of pregnancy tests is 97% .
In what cases can a test give a false positive or false negative result?
First of all, the test may show a false result if it is expired or has become unusable due to improper storage, so tests should only be purchased in pharmacies and you should always check the integrity of the packaging and the expiration date of the test.
The test may give false results if performed incorrectly without following the instructions exactly.
Too much may lead to an error early implementation test when the level of human chorionic gonadotropin is still low. In this case, the test gives a false negative result, that is, no pregnancy, while the woman is actually pregnant. Sufficient to be detected by test hormonal changes become no sooner than two weeks after fertilization eggs, so run to the pharmacy for a test the day after unprotected sex on a “dangerous” day it’s useless: you’ll just calm down in vain.
If the test is negative but you still think you are pregnant, it is recommended that you take your time and repeat the test in a few days.
Ovarian dysfunction can lead to a false positive result.
Taking hormonal medications can blur the picture.
With irregular menstrual cycle The pregnancy may be less than expected, so the test may show a false positive result.
IN in rare cases when human chorionic gonadotropin is produced by a tumor (choriocarcinoma, chorionepithelioma, hydatidiform mole, ovarian cyst), the test gives a false positive result.
At pathological pregnancy(threatened miscarriage, ectopic pregnancy) test results may be inaccurate. If there is a threat of miscarriage, the test may become negative suddenly. It happens that a negative result becomes the first sign of a miscarriage.
The picture may be blurred by use large quantity liquid on the eve of the test, since liquid can dilute the urine and reduce the concentration of hCG in it.
Kidney pathology can lead to an incorrect result.
Remember that no test replaces medical consultation, since there is always the possibility of misinterpretation of the results or false result test.
If you receive a positive test result and want to continue the pregnancy, you need to make sure that the pregnancy is developing normally and in a typical location. After all, the test does not make it possible to determine the location of pregnancy, so it does not allow diagnosing ectopic pregnancy.
If pregnancy is unwanted for you, you should not waste time; it is better to consult a doctor immediately. After all, early termination of pregnancy helps prevent abortion complications that can lead to infertility in the future. Therefore, it is necessary to go through as soon as possible necessary examination and decide on the method of termination of pregnancy.
If the test result is negative and there is no menstruation, you must work with your gynecologist to find the reason for the delay!
