The ovulation test detects the peak of the LH hormone released by the pituitary gland and leads to the release of the egg from the ovary 24-48 hours later.
To do the ovulation test properly, it should be started several days before the expected date of ovulation, about three days before (for example, if the woman has her period every 28 days and theoretically ovulates on day 14, start testing on day 11-12 of the cycle). The first morning's urine should not be used and should be repeated twice on the day about 12 hours apart. In addition, the patient must be persistent and do the test daily until it is positive.
The test uses test strips and/or digital devices, which have different sensitivities, which are measured in the international measurement of units per litre (IU/L). This parameter indicates the minimum amount of LH that the test can detect in the urine (10 to 40 IU/L). Thus, tests with high sensitivity (10 IU/L) are more likely to detect a peak of LH even though it is lower than those with low sensitivity (40 IU/L).
Thus, a negative ovulation test can also be due to the following reasons:
- The woman does it with the first urine in the morning or without following the instrucitons correctly.
- The patient is tested too far in advance of the LH peak (e.g. patient with long cycles).
- The LH peak can be short (2 hours) and when the patient is tested, too much time has passed for the test to be positive. It is therefore advisable to do it twice a day.
- The sensitivity of the test used is low and does not detect the specific LH peak of the patient studied.
On the other hand, it is worth noting the possible false positive results: the test may be positive but there is no ovulation:
- The peak LH produced from the pituitary gland may be high but not followed by ovulation at ovarian level.
- In women with polycystic or multifollicular ovaries there is a peak of LH but no consequent ovulation.
Conclusion: Ovulation tests are not accurate tests and should be carried out carefully in the knowledge that they can lead to false negative and/or positive results.
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