Causes of a false positive pregnancy test

Causes of a false positive pregnancy test

A false positive test result shows the presence of pregnancy in its absence. That is, not being pregnant, a woman gets two strips on the body of the dough. Why is it so?

The reasons for a false positive pregnancy test can be very different. And in order to understand why the test can deceive, we will briefly describe the principle of its operation.

A special reagent is applied to the dough strip, which reacts to the hCG hormone, binding to it and staining reddish-pink. The canvas of the test has two zones: a control and a test zone. The first is designed to confirm that the test is usable (i.e., it works properly), it reacts just to urine. The second is manifested only if enough hCG is present in the urine. The most sensitive pregnancy tests are able to catch it at the level of 25 mIU / ml. To such indicators, the hormone chorionic gonadotropin in most cases increases by the first day of delay.

That is, in fact, the pregnancy test determines not the pregnancy itself, but an increased level of hCG in the human urine. Normally, it rises only in women and only after fixing a fertilized egg in the uterus: the forming placenta (or rather the chorion) begins to produce this most human chorionic gonadotropin, which in the first weeks of pregnancy is rapidly increasing, doubling every two days and reaching its peak at 8-11 weeks. But the growth of hCG in the body (and in particular in the urine) of a person can be caused not only by pregnancy, and in principle even men can use the test to determine its level, which can become an early diagnosis of tumor development in the body.

All because to produce chorionic gonadotropin are also capable of various kinds of education: cysts, tumors. Therefore, in the absence of pregnancy, an elevated level of this hormone can indicate the course of the pathological process in the body.

HCG in urine may remain at high elevations for some time after abortion or miscarriage. If a woman has recently removed an ectopic pregnancy, traces of hCG may also persist.

In addition, some hormonal drugs are also able to increase the level of gonadotropin, affecting the test results.

In addition to the really elevated level of hCG in the absence of pregnancy, false positive results may be the result of using a low-quality test or incorrect reading of information. On some test strips, after drying the liquid, a vague trail develops at the site of the second strip, which can be erroneously interpreted as a positive result. Therefore, the instruction always writes a warning that the result is reliable, estimated no later than 5-7 minutes after dipping the test strip into the urine. Note that for a positive result, you should take the presence of a second strip, the same color, clarity and width from the control.

  • The presence of neoplasms in the body (chorion of the uterine epithelium, bladder skidding);
  • A recent abortion, miscarriage, or removal of an ectopic pregnancy;
  • taking hCG-containing medications;
  • low-quality test;
  • violation of the storage conditions of the test;
  • incorrect evaluation of test results.

It should be said, that false-positive test results are relatively rare. Where more often women get false-negative results, when a pregnancy test does not show it. In the vast majority of cases, this is due to too early home testing: the level of hCG in the urine is still very low so that the reagent can "detect" it.

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