One of the most frequent questions we receive from our readers is how to perform the pregnancy test to get a reliable result.
In the absence of menstruation, the most important pregnancy symptom, or any other symptom, many women want to confirm the suspicion by means of a pregnancy test, a method that allows, with a high margin of safety, to know if they are pregnant or not.
Types of pregnancy tests: blood and urine tests
There are two types of pregnancy tests: of blood and urine. Both detect the presence of the human chorionic gonadotropin hormone (hCG), also known as pregnancy hormone. This begins to occur after the implantation of the embryo and remains at high levels during the first trimester of pregnancy, although after that period it decreases, so if you took a pregnancy test after the first trimester it could be negative.
He blood test It is done in a laboratory and can detect pregnancy even before the first lack of menstruation. Quantitative tests can detect hCG levels as small as 1 mIU / mL, while urine tests require 20 to 100 mIU / mL, depending on the brand. An accurate result can be obtained in a few hours, including determining the exact age of the fetus, as well as detecting abnormal pregnancies such as an ectopic pregnancy, a molar pregnancy or a potential spontaneous abortion.
He urine test It can be purchased at the pharmacy without a prescription to perform at home. It consists of an absorbent strip, normally presented inside a plastic cartridge, which reacts to the presence of human chorionic gonadotropin in the urine.
They have a reliability of between 75 and 97 percent if the result is negative, while if the result is positive the reliability is 99 percent.
There are more sensitive than others, depending on the brand. Try to buy the ones that detect the lowest concentration of hCG. For example, a test that claims to detect hCG at 20 mIU / ml (International milli-units per milliliter of urine) will be more sensitive than one that claims to detect it at 50 mIU / ml.
How the pregnancy test is performed
He blood test It is done in a laboratory by extracting a blood sample from the woman. It does not require fasting and can be done at any time of the day.
The urine test is done at home. The first thing you should do when opening the test is to read the instructions in the attached brochure since the way to do it may vary from one brand to another. While it can be done at any time of the day, for greater reliability it is recommended to do it with the first urine in the morning, to make sure there will be more concentration of the hormone.
If you follow the manufacturer's instructions, you will see that the procedure is very simple and practically does not lead to errors. You must develop the test, remove the cover of the test strip and place it for 5 seconds in direct contact with the urine while peeing. Once the urine is collected, you must recap the test (it is important that it does not come into contact with any other substance), place it on a flat surface and wait 3-5 minutes to read the result.
The urine test result
Each brand has a different result reading system. The most common is that of two stripes for positive, even if they are dim. One of them indicates whether the test has been performed well and the other indicates the presence of the pregnancy hormone in the blood. Therefore, the presence of a single line indicates that the test has been done well and the result is negative.
Some tests, instead of the system of stripes or symbols, incorporate a small digital screen in which the result and the weeks of gestation are indicated. In any of them, if no result appears, it is most likely that the test is poorly performed, so the test must be repeated.
False negatives and false positives
The result may be negative when you are actually pregnant. This may be because you have done the test too soon so that the concentration of the pregnancy hormone can be detected in the urine. If the rule still does not come you must repeat the test a few days later or a week.
The false positive result, that is to say that the test yields a positive result when you are not pregnant, is very rare. It may be due to having suffered a spontaneous or voluntary abortion in the last eight weeks, having taken a medication to increase fertility that contains hCG, having an ectopic pregnancy (produced outside the uterus) or an anembryonic pregnancy (no embryo present). These circumstances can increase the level of the human chorionic gonadotropin hormone even without real gestation.
We hope to have clarified what is a pregnancy test and how is it performed. In a next post we will talk about when to take the pregnancy test, also a very frequent concern when considering the possibility of pregnancy.
