By Dr. Liz Kane

What is IUI?

IUI (intrauterine insemination) is a procedure in which concentrated sperm is placed into the uterine cavity at the time of ovulation. It is usually a quick, safe, and painless procedure that involves placing a speculum to visualize the cervix, and then inserting a small catheter through the cervical canal into the upper uterus, where the sperm can swim into the fallopian tube and find the ovulated egg. This procedure can be performed by a physician (fertility specialist or OBGYN) or a mid-level provider (ie. nurse practitioner or physician assistant). Learn more in The Scoop on IUI

Timing of IUI is critical

Once a mature egg is released from the ovary, the egg must be fertilized within about 24 hours for pregnancy to occur. To pinpoint this timing, your physician will either use ultrasound monitoring at the clinic or will have you use Ovulation Predictor Kits at home. Monitoring at home through Ovulation Predictor Kits can save time and money -- a pack of 7 ovulation tests costs just $18 compared to hundreds for an ultrasound. And one study of 719 patients showed both methods had similar pregnancy rates. 

The most accurate way to time insemination using home monitoring is by ovulation tests, aka Ovulation Predictor Kits (OPKs).

The most accurate way to time an insemination using home monitoring with ovulation tests. Because fertility treatments are not often covered by insurance, ovulation tests or OPKs are a low-cost option to help you and your physician determine the optimal timing for an IUI procedure (12-36 hours after positive result). 

You might be wondering—when during the day are you most likely to get your positive result? This study found that people most often got their positive test results at lunch-time, between 11 am and 3 pm. 

The trigger shot

Your doctor can also precisely control when an egg is matured by using what is informally called a “trigger-shot” that induces an egg to mature and ovulate within 24-36 hours. The trigger shot is usually composed of human chorionic gonadotropin (hCG), which is structurally similar enough to luteinizing hormone (LH), the hormone that induces eggs to mature and ovulate, that your body reacts the same way hCG as it would to LH. This option usually involves blood-work and ultrasounds and can be more financially burdensome for those that are self-paying for fertility treatments. 

Timing insemination - fresh vs frozen sperm 

If the procedure is using frozen sperm (say, from a donor), it is especially important to time the introduction of sperm as close as possible to ovulation. That is because sperm that has been frozen is estimated to live in a woman's body for at most 24 hours. Because of this some physicians recommend doing an insemination the day your OPK is first positive and again the following day in order to maximize the chances of sperm arriving in the vicinity of the egg when it is released.

How to use Ovulation Predictor Kits

After you follow the test instructions, pee on the stick, and wait for a result, take a look at the test window. This test window can display two lines—one for the control line (C) to make sure the test worked and another, the test line (T) that shows the ovulation result. 

Unlike a pregnancy test, two lines alone is not a positive result since your body makes LH at low levels throughout your cycle. A result is only positive if the test line (T) is as dark or darker than the control line (C) line. 

You’ll want to be sure your test is 100% positive before you inseminate. If your test line is almost as dark as the reference line, but not quite, it is not yet a positive result. 

Check out The Ovulation Test Cheat Sheet. And learn more about our ovulation tests here.

Recommended ovulation tests for IUI

The Natalist Ovulation Tests are recommended for women undergoing IUI because they are easy to use and reliable (over 99% accurate).