Ovulation Predictor Kits (OPKs)
Why would you use an Ovulation Predictor Kit?
An Ovulation Predictor Kit is a home test that can be used to help you determine if and when you are ovulating by detecting the level ofluteinizing hormone (LH) in your urine. In most women, the level of luteinizing hormone rises slightly right before ovulation. Using ovulation predictor kits during specific times of the month allows a woman to pinpoint when that surge occurs and estimate fairly accurately when ovulation will happen.If you are trying to get pregnant, you might use this test to figure out approximately when you will be ovulating and thus, the best times to have intercourse. If you have been trying to get pregnant with no success, this test will also help you--and possibly your doctor--determine if your body is indeed releasing an egg during your monthly cycle. Finally, some women utilize the OPK tests to prevent pregnancy by using them to determine when they are most fertile and avoid intercourse during those time periods.
What to expect
You can purchase Ovulation Predictor Kits in a variety of places, including K-mart or Target. Some online retailers will offer a discount for bulk purchase which is helpful if you have an irregular cycle and tend to use alot of OPK’s each month. OPKs are almost always located near the home pregnancy tests in the typical retail store.
Most Ovulation Predictor Kits usually contain 7 individual tests that appear almost identical to a home pregnancy test in shape and size. They typically consist of a “pee stick” wrapped in a foil or plastic covering. One end usually has a thumb grip and the other is an absorbent tip that is passed through the urine. In the middle you will usually find one or two windows where the control and result lines will appear. Some brands will provide a cover for the absorbent end so that you can lay the stick down while waiting for results without worrying about having the urine covered tip exposed on your counter.
Since you are attempting to find the LH surge and ovulation during your cycle, you will want to start testing prior to when your best estimate ofthat date would be and continue testing until the OPK indicates that you have reached your surge. This means that if your cycles vary from month to month or you have an extremely long cycle, you may use more tests in a month than a woman with a short or regular cycle. The most widely used method of calculating when to start testing is to take the number of days in your shortest cycle and count backwards by 14-16 days. The result will be the cycle day on which you should begin using the OPKs. (Note: Cycle days are counted from the date your period begins until the day before the next period begins). For example, if your shortest cycle in the last six months was 27 days, you would begin testing on day 11 or 13. In addition to this “rule of thumb”, the OPK box usually contains which days you should use the test based on various cycle lengths.
The best time to use the OPK tests is early afternoon or evening. This is due to the fact that occasionally your body will experience an LH surge inthe morning but it will not show up in your urine until several hours later. By testing mid-day you are more likely to catch a surge if it happens that day. It is a good idea to test the same time each day. Use the test by placing the absorbent tip into your urine stream for several seconds and then reading the results in the test window after waiting for the time specified on the kit’s instruction leaflet. If you want to, you can also place the urine into a sterile cup and dip the absorbent tip of the OPK into the cup for several seconds.
Every time you use an OPK test, one line will appear in the window. This is the control line and is there for use as a comparison to the result line and to let you know that the test is working properly. At some point during your cycle a second line (result line) should appear. It may be faint at first – this is not a positive test result. When this result line becomes as dark or darker than the control line, you have gotten a positive OPK test and will most likely ovulate within the next 12-48 hours. (Note: Some brands of OPKs consider it a positive result only if the test line is darker. Other brands consider it a positive result as soon as the result line is equal in darkness to the control line). If you are trying to get pregnant, at a minimum you should have intercourse on the day your test is first positive and for at least two to three days after.
Problems that may arise and ways to troubleshoot
It is important to note that the use of Clomid may produce false positives in an OPK test. Many manufacturs suggest waiting several days after taking Clomid to use an OPK. I have also read that Pergonal, Humegon and Repronexcan also cause false results.
If you do not get a positive result there may be several different reasons. First, you may have missed your surge. Some people need to test earlier in their cycle and some need to test more than once per day in order to catch their LH surge. If you try more frequent testing and more than one brand of test and still find that you are not detecting an LH surge, you may want to discuss this with your doctor. You may have a line in the results window for several days that gets darker each day until finally becoming a positive result. This is not unusual. If you are trying to get pregnant it is not a bad idea to begin having intercourse when the line gets close to being an actual positive result rather than waiting until it is truly positive.You may experience a positive test one day and then another positive a day or two later. This, too, is not unusual as you may catch the LH surge on both the way up and down. If you do not have a line in the control window, the test may be defective and you may want to consider trying again.
Lastly, it is possible to have more than one LH surge in a cycle. Often times, the body will gear up for ovulation several times, giving several false LH surges before producing the true surge that releases the egg.
I strongly suggest starting testing very early in your cycle when you first begin using OPKs. You are more likely to find your LH surge this way. I went by the “rule of thumb” and charts on the pamphlet for months with no success before testing earlier than they said and finally getting a positive test. It turned out that I usually ovulate way before the days they were telling me to begin testing. When you first start using OPKs, it might seem like an impossible task trying to decipher the “dark” or “darker” color coding system (I can’t tell you how many pee sticks I’ve held up to the light trying to figure out the subtle color shades). Don’t stress. It will probably be pretty obvious when the actual surge occurs.
I mentioned above that OPK tests look a lot like a home pregnancy test (HPT). Since I use a lot of both, I always have both on hand. I also switch brands of both a lot depending on what is available at the store and what is priced reasonably. Needless to say, I have a variety of brands of each in my cabinet. One month I accidentally used an OPK thinking I was taking a pregnancy test and was quite surprised by the results. I would definitely suggest keeping your various pee sticks in separate places to avoid this confusion. Many women also use basal body temperature charting (BBT) to track ovulation. I use this in conjunction with the OPK tests since the OPK test tells you that you are ovulating prior to it happening but the BBT charting shows more after you have already ovulated.
Finally, as a side note, there are also saliva test kits, ovulation monitors (expensive), and mucus test kits that can be used to help detect ovulation.