A rapid pregnancy test can give both false positive and false negative results. It all depends on the quality of the manufacturer, the woman taking hormonal drugs and many other factors.
How does a pregnancy test work?
The urine of a pregnant woman contains chorionic gonadotropin, a special hormone that is produced by the structures of the embryo after it is attached to the fallopian tube or uterus. HCG is produced in the mother's blood and then excreted through the kidneys. Any express test is based on a type of chromatographic analysis called immunochromatography. It is based on the interaction of the analyte with antibodies to it. In the urine of a pregnant woman, 7-10 days after fertilization, the level of hCG is 25 mIU / ml. This is the minimum concentration that is immediately detected by immunochromatographic tests.
Pregnancy tablet systems are more advanced tests. Due to the simplicity of conducting them, the occurrence of errors is minimized - a drop of urine is applied directly to the test itself.
Incorrect use of the test
Young ladies who are afraid of unwanted pregnancy, as well as women who have long dreamed of a child, often wonder whether the test can be wrong. This largely depends on compliance with the rules for its conduct. For example, if you "overexpose" the test for more than 5 minutes, as indicated on the package, a faint false positive streak may appear. It occurs due to the destruction of the conjugate and the release of the dye due to the evaporation of water from the surface of the express test. To “be sure”, you should not wait 10 minutes instead of 5. Nothing good will come of it. It is better to carefully study the instructions with visual photos.
Poor quality manufacturer and drug intake
In low-quality tests, blurry spots can form, which most often women like to mistake for a false positive second strip. This is due to the fact that the antibody-hCG-dye complex reaches the reaction zones later than the dye is cleaved from the conjugate. In a woman taking drugs containing hCG, for example, "Profazi" and "Pregnil", which stimulate ovulation, at the end of the course of treatment, the level of the hormone can persist for up to two weeks. It is better to postpone the test for this period, otherwise it will show incorrect results.
Electronic tests have become widespread, in which there is no need to evaluate the result, since the screen displays “yes” or “no”.
False negative result
False negative test readings are quite common, in contrast to false positives. Most often, they are obtained when the gestational age is still very small, and hCG is contained in less quantity than is needed for the reaction of the text. It also happens that the test itself is not sensitive enough. Then, in the early stages, it is guaranteed not to show pregnancy.
