Table of contents:
- How pregnancy tests work
- When to take a pregnancy test
- Why rapid pregnancy tests lie
- How to do a pregnancy test correctly
2023 Author: Malcolm Clapton | [email protected]. Last modified: 2023-05-22 06:26
Even a perfect test will lie if you break simple rules.
Today you can buy express pregnancy tests in every pharmacy, and even at the supermarket checkout. They are easy to use and reliable: doctors estimate their accuracy at 99% Pregnancy Tests. But often such tests lie.
How pregnancy tests work
Absolutely all pregnancy tests check whether there is a special Pregnancy Tests hormone in the urine or blood (if we are talking about a laboratory test) - human chorionic gonadotropin, abbreviated as hCG. It begins to be produced as soon as the fertilized egg attaches to the wall of the uterus.
If there is no pregnancy, hCG has nowhere to come from. If it is, hCG will be required.
Usually, the egg is attached to the uterus six days after fertilization. During this period, it is pointless to do the test: it will not show anything. But then the level of hCG increases rapidly, doubling every 2-3 days.
When to take a pregnancy test
Already 8 days after ovulation, during which the egg meets its sperm, the level of hCG becomes sufficient so that pregnancy can be recorded using a laboratory blood test.
A few days later - that is, on the 10-12th day after fertilization - the usual pharmacy tests will also see pregnancy.
Although the instructions for many of them promise an accurate result already on the first day of the delay, doctors advise not to rush Home pregnancy tests: Can you trust the results? … The reason is simple.
If you ovulate on the 10-14th day of the cycle, then by the beginning of the next cycle, at least 13 days will pass from the moment of fertilization. This means that the test will beep to you with two stripes.
However, ovulation can shift. If the release of the egg took place on the 22nd day of the cycle, then by the beginning of the delay, the actual gestational age may be less than 7 days. This means that even perfect tests most likely will not fix anything.
If your cycle is longer or less than 28 days, it is even more confusing.
Therefore, in order to get the most accurate result, it is worth waiting 5-7 days from the start of the delay.
If you are pregnant, the level of hCG by this time will in any case be such that even the cheapest tests with low sensitivity will unequivocally recognize it.
But even if you meet all the deadlines, the test can still mislead you. For example, he will not see a high level of hCG and show a negative result with an existing pregnancy, or, on the contrary, will give out two strips, although it does not smell like pregnancy. To be fair, let's say that it's not so much the test that is to blame as you are. Five reasons for false-positive pregnancy tests.
Why rapid pregnancy tests lie
1. You used an expired or damaged test
Rapid tests contain special highly sensitive substances that react to the level of hCG. It is they who, upon contact with the urine of a pregnant woman, are painted in a bright second strip or plus sign.
But if the test is expired or stored improperly, the sensitivity of these substances may decrease. As a result, they will give a negative result, which may turn out to be false.
What to do
Buy tests only at pharmacies, where, unlike supermarkets, they try to ensure the correct storage conditions. When buying, be sure to check the expiration date.
2. You bought a test with low sensitivity
The sensitivity of rapid tests is indicated by numbers - 10, 20, 25, 30. These numbers indicate the concentration of hCG in urine (in mIU / ml), which they are able to capture. The higher the number, the less accurate the test. The most expensive and accurate options have a sensitivity of 10. But cheap ones may not catch hCG and deceive you by showing a negative result.
What to do
When buying a test, be sure to check with the pharmacist how sensitive it is. Also, this information can often be found on the packaging and always in the instructions.
3. You did the test this afternoon
It is not for nothing that the manufacturer speaks of morning urine in the instructions for the absolute majority of tests. It is more concentrated, there is more chorionic gonadotropin in it, which means that the test will be more reliable.
In the afternoon, the hCG content in the urine is lower.
What to do
Use the test exclusively in the morning, as instructed by the manufacturer.
4. You drank a lot of water before taking the test
Water dilutes the urine, which lowers hCG levels. The rapid test may not sense the hormone and give a false negative result.
What to do
Try not to eat or drink anything before the test.
5. You did not look at the results in time
The instructions for each test specify the rules for its use. For example, like this: "The result can be evaluated in 4-5 minutes after the test, but no later than 15 minutes." These minutes are not taken from the ceiling.
The lower limit indicates the time it takes for the test for the sensitive substances contained in it to react to the hCG level. If you look at the test before the agreed time, the second strip (or the plus sign in the corresponding window) may not yet appear and you will see a false negative result.
If you look at the strip after the time indicated as the upper limit, you run the risk of getting a false positive result. Evaporated urine can leave a line that can be easily confused with a second strip.
What to do
Before using the test, read the instructions and strictly follow them.
6. You are taking certain medications
Some diuretics and antihistamines affect the composition of the urine by diluting it. This lowers the level of hCG, which means there is a risk of getting a false negative result.
Other drugs, on the other hand, can give you two strips, although in fact they do not. These medications include:
- some tranquilizers and sleeping pills;
- fertility drugs.
What to do
If you are taking any of the medicines on this list, you should not rely on the rapid test paper. To determine if you are pregnant or not pregnant, have a lab blood test done.
7. You are sick
If your urine is high in blood or protein, this can also affect your rapid test result. But here it is important to note that such a situation itself is extremely unhealthy. Blood in the urine indicates abnormalities in the functioning of the bladder or kidneys, high protein indicates internal inflammation.
Therefore, it is likely that fever and / or discomfort in the genital area and kidneys will be attached to the erroneous two stripes on the test.
What to do
Do not rely on a rapid test if you have a fever and lower back and lower abdominal pain. With such ailments, it is necessary to consult a therapist, gynecologist or urologist as soon as possible, so as not to miss a serious illness.
8. You develop an ovarian tumor
Certain types of tumors can trick the test into showing two stripes.
What to do
Having received a positive result, do not delay the visit to the gynecologist. The physician will conduct research, during which he will establish the actual gestational age (if any) or send you for additional tests and to specialized specialists.
How to do a pregnancy test correctly
- Read the instructions. And follow it, of course!
- Remember the rule: if you are healthy and the test is positive, the chance of pregnancy is 99%. A negative result can be false for up to a week after the delay.
- Choose tests with a high sensitivity level. 10 is ideal.
- Do the test in the morning, not in the afternoon, and even more so not in the evening.
- Try not to drink at least an hour before the test.
- Do not rely on the test if you are taking the medications listed above or if you are concerned about fever and lower abdominal pain.
- Buy two tests at once to be able to double-check the result.
- If the rapid tests contradict each other, you shouldn't wonder what is the matter. Do a laboratory blood test to get a reliable result.
Important! A positive test, even if you have been waiting for it for a long time, is, alas, not a reason to rejoice. An increased level of hCG in the urine can be recorded, including with an ectopic or frozen pregnancy. Therefore, having received two strips, go to the gynecologist as soon as possible.