Conception is a complicated process. Very few sperm are strong enough to swim from the vagina through the cervix, into the uterus, and up the fallopian tubes to meet and fertilize a woman's egg. To complicate matters more, the sperm must reach the egg within a precise window of time (ovulation) in order for fertilization to take place. Intrauterine insemination (IUI) aims to make this process as easy as possible.
IUI is a procedure for artificial insemination in which the sperm is prepared and placed directly in the uterus around the time of ovulation to be closer to the egg. IUI aims to increase the chance of fertilization, so that it’s more likely the woman becomes pregnant.
How it works
Usually, sperm is placed in the cavity of the uterus by means of a fine catheter passed through the cervix. This ensures accurate timing of sperm in the uterine cavity, and bypasses any hostile effects of cervical mucus on the sperm.
IUI helps to prepare and place sperm in a woman's uterus, but it doesn’t affect her eggs. Therefore, IUI can be used within a natural cycle or in conjunction with hormonal stimulation if there is difficulty ovulating. IUI is usually a quick and painless procedure, performed in the office when a woman is ovulating.
Who it’s for
IUI is used when pregnancy is being attempted with donor sperm or previously frozen sperm. It may also be a good choice for people with:
- Unexplained infertility
- Cervical abnormalities
- Lack of ovulation (anovulation), in conjunction with ovulation indication
- Ejaculation problems
The procedure will only be performed if a woman has healthy fallopian tubes to ensure that the egg or a fertilized embryo can travel to the uterus.
Possible side effects*
- Increased chance of getting pregnant with multiples (triplets, quadruplets, and high-order multiple births), which can have health risks for both the mother and babies
- Small risk of infection
The chance of birth defects is not increased with IUI. As with natural conception, birth defects occur in 2% to 4% of children.†
*This may not represent all side effects. Please discuss with your healthcare provider.
†Intrauterine insemination (IUI) Fact Sheet from ReproductiveFacts.org, the Patient Education Website of the American Society for Reproductive Medicine. Revised 2016.
What women can expect in a cycle
Your doctor may use ovulation induction medications, such as estrogen blockers or gonadotropins, to stimulate your ovaries to produce, mature, and release one or more eggs.
When your eggs are mature, you’ll receive a “trigger shot.”
A semen sample will be collected from your male partner or donor and may be screened for any diseases and genetic disorders. Your embryologist will prepare the sperm by “washing” and filtering them, removing any mucus and non-moving sperm. This leaves a concentrated solution of the most active sperm ready for IUI.
Your IUI procedure will be scheduled to happen within 24 hours of the “trigger shot.” During the procedure, your doctor will insert a speculum into your vagina to keep the vaginal walls apart. A syringe containing the prepared sperm is attached to a catheter, which is then inserted through the vagina. The washed semen sample is slowly injected into your uterus.
After the procedure comes a waiting period before a pregnancy test can be taken known as the “two-week wait.” This can be a difficult time, filled with hope and anxiety. Building a support network can help you during the wait.
Note that pregnancy tests measure the level of hCG in the urine or blood. Therefore, it’s important to take a pregnancy test only when advised by your doctor, because the test may pick up the hCG from the ovulation trigger injection and show a false positive result.
If you get the joyous news of a positive pregnancy test, your clinic will closely monitor your pregnancy with scans and blood work to ensure the health of you and your baby. You’ll be released to your OB when your pregnancy is 8 to 10 weeks along.
How successful is IUI?
How well IUI works depends on the reasons for your infertility. People with unexplained infertility, cervical abnormalities, or ejaculation problems typically have the best success. For infertility that has no known cause, pregnancy rates may double with IUI compared with no treatment at all. Treatment is also more successful when used in combination with OI medications.
Just like fertility, IUI cycles are usually less effective as a woman gets older. According to a 1998 study of the outcomes of 9963 consecutive IUI cycles, IUI resulted in pregnancy in approximately*:
- 11.1%-18.9% of women under 40 years
- 4.7% of women 40 to 45 years
- 0.5% of women over 45 years
Fertilization can be difficult to achieve. If IUI doesn’t work right away, it doesn’t mean that pregnancy won’t ever be possible. It may take more than one round of IUI to conceive successfully.
IUI is less expensive and less invasive than in-vitro fertilization (IVF), but pregnancy rates are also lower. A fertility doctor can advise how many cycles are best for you before considering a different fertility treatment.
*Starosta A, Gordon C, Hornstein M. Predictive factors for intrauterine insemination outcomes: a review. Fertility Research and Practice. 2020;6(23). Stone B, Vargyas J, Ringler G, et al. Determinants of the outcome of intrauterine insemination: Analysis of outcomes of 9963 consecutive cycles. J Obstet Gynecol. 1999;180(6):1522-34.
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