Home pregnancy test: Can the results be trusted?

This is an automatically translated article.

1. What is a pregnancy test?

Pregnancy test strip is a qualitative test device that detects the level of hCG hormone (Human Chorionic Gonadotropin). It is a compound secreted by the placenta and found in the urine of women. This hormone is only produced when the placenta has begun to form and develop.
The amount of hCG will gradually increase during this period. Test strips are designed to determine whether you are pregnant or not based on these hormone levels. The hCG hormone is considered a pregnancy hormone because it is produced by the placenta after the embryo has implanted. The amount of this hormone will increase extremely quickly after the embryo has implanted and secreted the hormone into the blood. Pregnancy test or blood test are based on the principle that the presence of HCG hormone levels in the blood or urine to determine whether you are pregnant or not.
A pregnancy test will have 2 lines, 1 line as a standard and a line showing the result. If you are pregnant, the test strip will show if hCG is present in the urine. This is the reason why many people often use the word "two lines" with the meaning "just found out I'm pregnant", "pregnant sign" or "newly pregnant".

On the contrary, a negative result, which means that after the test, there is still only 1 line, it means that you are not pregnant, or the amount of hormone is not enough for the test strip to recognize.
Any woman of childbearing age who is still menstruating should be advised to take a pregnancy test. It's important for your own health and also to be careful in your medication use and work environment.

2. When to take a home pregnancy test?

Many pregnancy test methods claimed by the manufacturer for effectiveness can be accurate from the first day of a missed period - or even before that. However, you are more likely to get a more accurate result if you wait until the first day of your next period.
Why is that, right after the fertilized egg becomes a zygote and develops into an embryo. The embryo then enters the uterine cavity and begins to attach to the lining of the uterus, this is called implantation, the placenta will form and produce the hormone human chorionic gonadotropin (HCG). This hormone is an extremely important substance in pregnancy and is used as an indicator of a woman's pregnancy. The hCG hormone enters your bloodstream and is partially metabolized in your urine.
During early pregnancy, HCG levels rise rapidly - doubling every 2 to 3 days. However, when you take a home pregnancy test too soon, hCG levels may not be present or very low levels making it difficult for the test to detect HCG.
Remember that your ovulation time may vary from month to month and a fertilized egg may implant in the uterus at different times. This can affect how long HCG is produced and when it can be detected in the urine. If your period is irregular, you may have miscalculated your period.

When a home pregnancy test is negative but you still think you are pregnant, it is important to confirm your pregnancy again and, depending on how long you are pregnant, your healthcare provider may Your doctor may recommend an ultrasound, repeat lab urine tests, or blood tests to measure HCG levels.

3. Notes on using home pregnancy test strips

With most tests, you either place the tip of the pregnancy test in your urine or dip the dipstick into the container of the collected urine. A few minutes later, the pregnancy test will show a result - usually a plus or minus sign, one or two horizontal lines, or the words "pregnant" or "not pregnant" on the display. Depending on the manufacturer, the test strips will show different results, but all are based on the principle that the presence of hCG in the urine.
You should follow the test instructions while waiting for a few minutes before removing the test strip from the urine vial to check the results. Most pregnancy tests have a line as a reference. For good quality test strips, when you dip the strip in your urine, whether you are pregnant or not, this control line is always visible to make sure your test strip is working properly. If the test strip does not show this line, use another test strip to test again.
Some home pregnancy tests are more sensitive than others. In other words, the amount of HCG needed to be detected in the urine to produce a positive test result will be lower depending on the manufacturer's specifications.
Another note is that the desk should always check the expiration date of the test strip and read the instructions carefully before you use it.

4. Accuracy of pregnancy test strips

Many current pregnancy test methods give 99% accurate results according to the manufacturer's claims. However, home pregnancy tests differ in the likelihood of pregnancy in women who have recently missed their period. If you have a negative test result but think you may be pregnant, repeat the test 1 week after your period is late or talk to your healthcare provider.
In necessary cases, the doctor may order more detectable tests such as measuring HCG levels in the blood or fetal ultrasound to check if a gestational sac is visible.
Fertility drugs or other medicines containing HCG may affect the results of a home pregnancy test. However, most medications, including antibiotics and oral contraceptives, do not affect the accuracy of a home pregnancy test.

5. Can a positive or negative pregnancy test be a false result?

5.1. False Positive Pregnancy Tests Although rare, you can still get a positive result from a home pregnancy test while you are not actually pregnant. This is called a false positive.
False positives can happen if you have a miscarriage soon after a fertilized egg attaches to the lining of your uterus (regression) or you take a pregnancy test too soon after taking fertility drugs containing HCG . An ectopic pregnancy, menopause, or problems with your ovaries can also contribute to skewed test results.

Some false positive cases of pregnancy test such as:
Due to infertility treatment: During artificial insemination, the doctor will inject a large amount of hCG hormone into the woman's body. The purpose of this is to stimulate ovulation, in order to facilitate artificial insemination. If the pregnancy test takes place while the body still has some amount of hCG hormone, using the test strip can lead to a false positive result. Due to the failure of artificial insemination: It is possible that, after the embryo implanted in the uterus for a while but could not survive and develop anymore, it will lead to a false positive. At this time, the placenta has grown and produces a sufficient amount of hCG hormone for the test strip to detect, leading to a false positive pregnancy test. Due to ectopic pregnancy: Sometimes, people who have IVF will have an ectopic pregnancy. At this time, the placenta is still developing normally and producing enough hCG hormone for a pregnancy test to detect. However, the larger the fetus, the higher the risk of miscarriage and stillbirth. At this time, the hCG level is still present in the body and the pregnancy test detects it, creating a false positive result. 5.2. False negative pregnancy test In addition to a false positive result, you can also get a negative result from a home pregnancy test but you are actually pregnant. This is called a false negative. You can get a false negative if you:
Take a pregnancy test too soon: The sooner you take a home pregnancy test after a missed period, the harder it will be for this test to detect HCG. For the most accurate results, repeat the test one week after your missed period. If you can't wait that long, ask your healthcare provider for a blood test. Check the test results too soon: You should allow the pregnancy test strip to come into contact with your urine exactly as directed on the package. Use diluted urine: For the most accurate results, do the test first thing in the morning - when your urine is most concentrated.

6. What to do if the result is false negative or false positive

Based on your test results, consider taking the following steps:
Your home pregnancy test is positive, or you have tried several home pregnancy tests and received different results. Make an appointment with your healthcare provider. You may need a blood test or an ultrasound to confirm your pregnancy. The earlier pregnancy is confirmed, the more effective antenatal care you can begin. Your home pregnancy test is negative. If your period hasn't appeared, repeat the test in a few days or a week - especially if you had the test before or shortly after your period missed. You keep getting negative test results, but your period hasn't started or you still think you might be pregnant. Check with your healthcare provider. Many factors can lead to a missed period (amenorrhea), including thyroid disorders, low body weight, ovarian problems, excessive exercise, and stress. If you're not pregnant, your healthcare provider can help you get your period back on track. To prepare for a healthy pregnancy, both husband and wife should have a reproductive health checkup 3-5 months before becoming pregnant.
The wife should:
Get vaccinated before pregnancy (especially against rubella because rubella in pregnancy is extremely dangerous ) Genetic testing to screen for genetic diseases before pregnancy

Check the status of gynecological infections to avoid affecting the health of the mother and the fetus. Especially, women over 35 years old, if they want to become pregnant (especially if they have never been pregnant), will have to have a very detailed health check. Secretions caused by pregnancy at this age often have problems: ovarian failure, premature birth, higher risk of fetal malformations, placenta previa, preeclampsia. The husband should:
Check reproductive health, detect diseases of testicular atrophy, physiological weakness, weak sperm... Sexually transmitted diseases, especially those that cannot be cured, are extremely dangerous. Vinmec currently has many comprehensive health care programs for couples, pregnant mothers and their unborn babies, including basic pre-marital examination packages, advanced pre-marital examination packages, and maternity packages. . Vinmec has a team of experienced doctors in the fields of obstetrics and gynecology, IVF, stem cells, gene technology, capable of synchronously and comprehensively deploying the most advanced assisted reproductive techniques today.
For specific information about fertility and maternity packages at Vinmec, please contact the hospitals and clinics of Vinmec health system nationwide.

Please dial HOTLINE for more information or register for an appointment HERE. Download MyVinmec app to make appointments faster and to manage your bookings easily.

Reference source: mayoclinic.org

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