Are pregnancy test strips accurate? How to read pregnancy test strips? Please give me a diagram

Pregnancy test strips are cheap and easy to test, and are the longest-used method for many women who want to test whether they are pregnant. So, are the results of pregnancy test strips 100% accurate? How to read pregnancy test strips?

Are pregnancy tests accurate?

Many women are used to using early pregnancy test strips to test whether they are pregnant, and hospitals usually use this method to test. Early pregnancy test strips are very convenient and quick to use, but will it give you a wrong message?

In fact, although the early pregnancy test strips are said to have an accuracy rate of 99%, you must not overly trust your self-test results. According to expert statistics, the correct test rate of early pregnancy test strips varies greatly, ranging from 50% to 98%. Why is there such a big difference? Gynecologists point out that when women do self-tests for pregnancy at home without any external guidance, the general test results can only achieve an accuracy rate of 50% to 75%. If this test is done in the laboratory in front of a doctor, the doctor can ensure that the test strips work properly, and the woman can use the test strips correctly according to the instructions, the test accuracy rate may be close to 100%.

The manufacturers of pregnancy test strips and ovulation self-test mirrors claim: "In the laboratory, it has been confirmed that the accuracy of today's early pregnancy test strips is as high as 99%. However, when using early pregnancy test strips, women must remember to follow the instructions meticulously to ensure that the test results are correct and reliable." However, in actual operation, it is not easy to use them correctly according to the instructions. The instructions of some early pregnancy test strips read: "Urinate at one end of the self-test card, with the absorption tip facing down, and the display window should not face the body to avoid splashing urine on it." Some early pregnancy test strips instruct users to "hold the urine burette and drop 3 drops of urine 3 cm above the urine dish at the bottom of the test strip." If you read the details of these instructions carefully several times and think them over again and again, there may be no problem. However, for a woman who is nervous and panicked because of the fear of pregnancy, mistakes are inevitable because she cannot calmly and patiently follow the instructions. Moreover, the test results are also confusing. Whether it is the color reaction or the line reaction, it is difficult to explain.

In addition, there are other obstacles to obtaining accurate test results. Like professional medical tests, pregnancy self-tests work by detecting HCG values, that is, human chorionic gonadotropin values. This hormone is produced by the placenta and generally appears in the urine a few days after pregnancy, but due to the small amount, it is not easy to test it at the beginning, and it will not become increasingly obvious until 10 to 14 days. (HCG values ​​can also be measured through blood tests, and they are much more accurate). Although many types of early pregnancy test strips indicate that women can do pregnancy self-tests after missing a normal menstrual period by 1 day, in fact, not all pregnant women emit HCG hormones at the same speed and amount. This varies from person to person. "If you do a urine test too early, the negative reaction presented may be wrong." Obstetricians and gynecologists say so. Therefore, it is best to do a pregnancy self-test two weeks after the menstrual period is late, so that the results will be more reliable.

The results are accurate only if all three conditions are met

Time: The result can be found at least 10 days after sex

The reporter learned that some early pregnancy self-test products claim that they can be used to test on the day of suspected pregnancy. Some couples who are anxious to know the results of "making a baby" or do not want to have a child so soon will rush to buy test strips to test the next day after having sex. The result is often that the second horizontal line does not appear, but this does not mean that there is no pregnancy. At this time, it is almost impossible to use early pregnancy test strips to test whether you are pregnant, because it takes several days for sperm and egg to combine into a fertilized egg, enter the uterus to implant, and form an embryo. HCG will not appear in the blood until a few days after pregnancy, and because of the small amount, it may not be detected at the beginning. If you do a urine test too early, the negative reaction presented may be wrong.

If you want to know the accurate results as soon as possible, you can refer to the two methods provided by Liu Mingxing to calculate the time:

Based on the last menstrual period: If the menstrual period is always regular and the cycle is 28-30 days, then the test strip can detect a weak positive result on the 3rd to 5th day after the menstrual period is late. For example, if the menstrual cycle is 30 days, the menstrual period came on the 11th of last month, and the woman had sex afterwards, then the pregnancy test strip can be used to test on the 3rd to 5th day after the 11th of this month, which is around the 14th to the 16th. However, this method is not applicable to women with irregular menstruation.

Take the time of intercourse as the standard: if a woman successfully conceives during a certain intercourse, then a weak positive result can be detected using an early pregnancy test strip 10 days after intercourse. To get a clear result, it is generally necessary to wait until 14 days later.

In addition, the concentration of HCG in morning urine is higher, so it is best to use morning urine for self-testing.

Dili: The test paper will be affected by moisture and affect the results

When buying early pregnancy test strips or pregnancy test sticks, you should choose those produced by regular manufacturers. When purchasing, pay attention to whether the packaging is intact. After taking it home, avoid storing it in a humid place. Before using it, pay attention to whether the product is still within the validity period. Since early pregnancy test products are mostly used in the bathroom, you should also pay attention to avoid getting the test strip wet when you unpack it for use, which will affect the results.

Renhe: Ovulation-stimulating drugs can cause "false positive news"

Some personal operation and physical factors may also lead to inaccurate results. Liu Mingxing said that the test should be carried out according to the instructions of the manual. Generally, the cotton wool of the test paper is soaked in urine for 6 seconds, and then the test paper is laid flat for 5 minutes before looking at the results. "If these two procedures are not carried out for enough time, the test paper may not have enough time to react, resulting in a false negative." Or some women who are eager to use early pregnancy test strips for testing may drink a lot of water in a short period of time to make themselves urinate, which may dilute the HCG content in the urine, making the test results inaccurate, and may also result in a false negative. "In some cases, the second horizontal bar has actually appeared on the test strip, indicating a weak positive, but because the HCG content in the urine is very low, the color of the second horizontal bar is very light. Some people do not understand, see the light color or do not notice it at all, and think they are not pregnant; but if you take the test strip to the hospital, our experienced doctors will know that they can see the faint horizontal bar."

There are also some special physical conditions that will cause the test paper to "falsely report good news." Liu Mingxing said that within one month after a woman has a miscarriage, HCG is still present in her body, and the test will be positive at this time. In addition, some infertility patients need to inject HCG to promote ovulation, and the HCG test will not turn negative until one week after the injection. "Some infertility patients go home and have sex immediately after taking the HCG injection. The next day, they get up and use the early pregnancy test paper to test and find that there are two bars. They are very happy. As a result, after a few days, they test it again and find that the color of the second bar is getting lighter and lighter. They are very anxious. In fact, this shows that the previous results were not due to pregnancy, but caused by the injection of exogenous HCG."

If pregnancy is detected, early prenatal check-up should be performed

Early pregnancy test strips can only perform qualitative tests on the HCG content in urine. Liu Mingxing said that even if HCG positivity is indeed caused by pregnancy, early pregnancy test strips can only tell you that you are pregnant, but cannot tell you whether the pregnancy is healthy or in what position, because fetal malformations such as ectopic pregnancy and hydatidiform mole can also cause HCG tests to be positive. Therefore, if you detect pregnancy with an early pregnancy test strip, you should go to the hospital for various prenatal examinations as soon as possible.

If you find a second horizontal line on the test paper after the test, but the color is "light", it may be a weak positive. You should first assume that you are pregnant. You can take the test paper to the hospital to consult a doctor, or go to the hospital to draw blood for a quantitative test of HCG content. If the self-test result is negative, but the menstruation has not come after a week, it is also worth noting. Symptoms of early pregnancy include nausea, vomiting, fatigue, lack of energy, breast swelling, picky eating, drowsiness, etc. If you have these symptoms and the self-test result of the test paper is negative, you should also go to the hospital for a check-up.

How to use pregnancy test strips correctly

First, be sure to read the instructions carefully and completely before using the test strip, and restore the reagent and urine sample to room temperature (20℃-30℃) before use. Take out the test strip from the original aluminum foil bag and use it as soon as possible within 1 hour.

Secondly, use a disposable urine cup or clean container to collect urine, tear open the aluminum foil bag along the cut, and take out the test paper for testing. Dip the end of the test paper with the arrow mark into the container containing the urine sample to be tested (the urine sample is not allowed to exceed the MAX line), take it out after about 3 seconds, and wait for 5-10 minutes.

Finally, pick up the pregnancy test strip and observe the test results. If there are colored bands on both the upper and lower ends of the test strip, it means you are pregnant. If the result shows that only a purple-red band appears on the upper end of the test strip and no colored band appears on the lower end, it means you are not pregnant. If there is no colored band, it means that the test strip has expired. At this time, you need to buy a new test strip and test again.

Early pregnancy test strips are disposable, so they cannot be reused. You can open the package only when you are sure you will use them, and they must be used within the validity period of the test strip. If the early pregnancy test strip is stored in a damp place for a long time, do not use it. Be sure to store it under normal greenhouse conditions.

Early pregnancy test strips generally recommend using the first urine test in the morning for women who have just become pregnant, and the results are more accurate. But for women who have been pregnant for some time, urine at any time of the day can be used for testing.