Can you always trust express pregnancy tests? This question is still open.
Experts assess the possibility of a false-negative pregnancy test at about 1-5%, but there is such a possibility.
The accuracy of a pregnancy test depends on its maker, on how closely you follow its instructions, on what medicines you take, and other factors.
How do pregnancy tests work?
Traditional express-tests are based on a simple principle of detecting human chorionic gonadotropin (hCG – a hormone which is produced by a female body immediately after the conception has happened but reaches the necessary for its identification level only one day after the fertilized egg is implanted into the uterine wall) in urine. It happens after approximately a week since the conception.
Pregnancy test results are more accurate after a missed period – in other words, at least 14 days after the conception.
Why can a negative pregnancy test be faulty?
You can get a negative pregnancy test result due to the following reasons:
- The most trivial cause of a false-negative pregnancy test is using an expired or defective because of the wrong storage conditions one. Before buying a pregnancy test, make sure the pack is intact.
- The time of implantation has an influence on the test result. It will come negative unless the fertilized egg cell has fastened to the uterine wall. If you do the test earlier it can provide a false-negative result because of low hCG. Implantation usually happens 6-12 days after fertilization. To get a trustworthy result, you must use a test 14 days after the sexual intercourse.
- Another reason for a negative pregnancy test can be your failure to follow the instructions. You should use it in the morning, the urine should be fresh – dip the stick into it as marked for the time specified in the instruction.
- You can get a wrong picture if you’re taking hormones: they change the proportion of hormonal levels in your body and lead to a negative pregnancy test.
- An incorrect result is often a consequence of some diseases. Women who have kidney problems usually get a negative pregnancy test.
- If you’re pregnant but the test has come negative there is a possibility of some pathology, such as an ectopic pregnancy or a miscarriage. A negative pregnancy test is often the first sign of danger which tells you a miscarriage can happen or has already happened.
- You get a wrong picture if you drink a lot of water before using a test. Excess fluid makes your urine thin – there is not enough hCG concentrated in it for an express pregnancy test to detect.
Can you get a false-negative pregnancy test after extracorporeal fertilization (IVF)?
A natural pregnancy or a result of extracorporeal fertilization – a pregnancy test detects it anyway. The presence of a fertilized egg cell leads to the production of hCG, and after the implantation of the embryo hCG reaches the level sufficient for identification by a simple over the counter pregnancy test.
It’s recommended to use the test not earlier that the 10th day after the implantation of the fertilized egg because using the test before this date is likely to lead to a false-negative result. When the test is used correctly you’ll be able to see bright two lines – a clear sign that you’re pregnant.
When the pregnancy test shows two lines you should immediately make an appointment with a gynecologist if you want your baby to be healthy. Follow the simple recommendations presented in this article, and they’ll make it possible for you to notice the changes related to pregnancy going on in your organism in time. The only thing you need to do is to set the right schedule of taking basal temperature measurements.
Why can the second line on a pregnancy test be faint?
Even a faint line on a pregnancy test is a sign of pregnancy. The reason for a vague result is a low concentration of human chorionic gonadotropin in your urine.
The second line provides you with the result at a particular moment after the missed period. The exactness of test results depends on the pregnancy test sensitivity.
If you have any doubts you’d better take another test after a few days or buy a more sensitive one. Anyway, the more hCG there are in your urine the brighter the second line on a test becomes.
Negative pregnancy test but pregnant – what should I do?
If your pregnancy has been confirmed but your hormonal background still hasn’t reacted to the changes you should consult a gynecologist and an endocrinologist. One internal organ’s dysfunction often causes a chain-reaction which involves other organs and systems of organs.
Considering that a false-negative test result may be a warning of a possible miscarriage or an ectopic pregnancy, the necessity of professional medical help becomes clear. Such a state of health is very dangerous for the fetus and the future mother.
How to eliminate a false-negative result?
If the reason for a false-negative test is low hCG level you should make an appointment with your doctor to pass an hCG blood test and an ultrasonic examination.
If the false-negative pregnancy test is a consequence of some pathological process you’ll require a complex diagnostic examination aimed at the identification of the pathology and further treatment.
Psychoemotional stress can also be a cause of a false-negative pregnancy test – in this case you’ll have to consult an expert to take measures that ensure the normal course of pregnancy.