When you want to know whether you are going to ovulate you take the ovulation test. Ovulation is preceded by a release of Luteinizing Hormone (LH) via the pituitary gland, and the test can detect its presence in the urine. As soon as there is an LH surge the ovulation prediction kit (OPK) displays a positive result.
What exactly is a positive result? While in pregnancy the home pregnancy test is designed to discover the presence of a hormone which is not there in the general run of things, LH is in your body always, and the test can detect traces of it even if you are not going to ovulate soon – so, it can be a bit confusing. Therefore, if the OPK test line is faint and quite narrow, it does not mean a positive result yet. You have to compare the resulting line with the control line. If you get a line of the same intensity or darker, the result is truly positive.
With some women the positive result is easily detectable, while with others the opk result may look dubious. It often happens when a woman has not been using the opk for a long time: she may regard any two lines as a positive result without actually comparing them, and end up mistaken about it. In this case a confirmation will be advisable, and you can go for another way to detect ovulation like fertility charting or a digital test which will leave no room for doubt as to the result.
Then again, if your opk test is definitely positive, it is no guarantee of your ovulating. Remember, the test indicates that there is more hormone LH in your urine than usual. You only know that your LH has come up to a certain level and you may be sure there was a hormone surge. What you cannot be sure of is whether the surge will lead on to the expected outcome. It may happen, or it may not.
Your body can actually emit the hormone, prime itself for an ovulation, and, finally, fail to ovulate. An illness or a stressful condition can cause this kind of failure. Certain conditions, for example, polycystic ovarian syndrome (PCOS) or premature ovarian failure (POF), are characterized by abnormally high LH levels and therefore may affect the results of the test. With such women, the tests are still more confusing than ever, showing a surge when there isn’t one, because such is their basic level – they need a much higher level for the result to be truly positive.
Some medications like Clomid can produce a false positive result, when the test is conducted while the drug is still in the body. Clomid heightens the FSH and LH levels, thus distorting the results of the opk.