When a woman conceives naturally, sperm travel from the vagina through the cervix (narrow, lower part of the womb), into the uterus (womb), and up into one of the fallopian tubes. If sperm arrive in a tube soon after the release of the egg from the ovary (ovulation); the sperm and egg can meet and unite (fertilization) in the tube.
The cervix naturally limits the number of sperm that enter the uterus, so only a small percentage of the sperm in the ejaculate actually make their way into the fallopian tubes.
Infertile women sometimes take medications (by mouth or as an injection) that cause their ovaries to mature several eggs at once. Intrauterine insemination (IUI) is a procedure that places sperm past the cervix and in a woman’s uterus around the time of ovulation making the passage to the fallopian tubes much shorter. The goal is to increase the chance of pregnancy by putting more sperm in contact with more eggs.
The most common use for IUI is when no cause for infertility is found.
IUI is helpful when a woman’s cervix has scarring that prevents the sperm from entering the uterus from the vagina. For example previous surgery on the cervix (cryosurgery, cone biopsy, Loop Electrosurgical Excision Procedure [LEEP], etc.).
IUI can also be used for couples in which the male partner cannot become or stay erect or is not able to ejaculate effectively, or at all. For example, retrograde ejaculation is when the sperm are released backward into the bladder, instead of through the penis, at the time of male orgasm.
Most of the time women who do not release an egg regularly (ovulate) can become pregnant through intercourse. Sometimes, IUI may be helpful.
Men may collect and freeze (cryopreserve) their sperm for future use before having a vasectomy, testicular surgery, or radiation/chemotherapy treatment for cancer. The sperm may be thawed later and used for IUI.
IUI is used when couples use sperm from a man who is not the woman’s partner to have a baby. This is called donor insemination (DI). DI is done when the male partner has no sperm or when the sperm quality is so low and in vitro fertilization is not an option. DI can also be used if the man has certain genetic diseases that he does not want to pass on to his children.
Most commonly, the man masturbates into a sterile glass or plastic cup or can be collected during sex in a special condom that is provided by the andrology laboratory, a laboratory that specializes in dealing with male health issues.
If a man has retrograde ejaculation, the sperm can be retrieved in the laboratory from urine he has collected.
Men who have a difficult time with erection or ejaculation despite using medications, as well as men with a spinal cord injury, may be able to produce a sperm sample with the help of vibratory stimulation or electroejaculation.
Once collected, the semen sample is then “washed” in the laboratory to concentrate the sperm and remove the seminal fluid (seminal fluid can cause severe cramping in the woman). This process can take up to 2 hours to complete. IUI is performed near the time that the woman is ovulating. The IUI procedure is relatively simple and only takes a few minutes once the semen sample is ready. The woman lies on an examining table and the clinician inserts a speculum into her vagina to see her cervix. A catheter (narrow tube) is inserted through the cervix into the uterus and the washed semen sample is slowly injected. Usually, this procedure is painless, but some women have mild cramps. Some women may experience spotting for a day or two after the IUI.
The success will vary depending on the underlying cause of infertility. IUI works best in patients with unexplained infertility, women with a cervix that limits the passage of sperm, and men who are unable to ejaculate effectively. For example, for unexplained infertility, the pregnancy rate with IUI is double that over no treatment. IUI does not work as well for men who produce few sperm or have slight abnormalities with their sperm and does not help women who have severe fallopian tube disease, moderate to severe endometriosis, or a history of pelvic (lower belly) infections. The success rates depend on whether fertility medications are used, age of the woman, and infertility diagnosis, as well as other factors.
If a woman is taking fertility medications to increase the number of eggs when she has an IUI, her chance of getting pregnant with twins, triplets, or more is greater than if she were not taking fertility medications. Having an IUI does not increase the risk of birth defects. The chance of birth defects in all children is 2% to 4% whether conceived naturally or from IUI. The risk of developing an infection after an IUI is small.
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