Intrauterine Insemination Explained
The objective of intrauterine insemination (IUI) is to introduce a quantity of sperm into the female partner’s uterus, and thereby facilitate fertilization. For IUI, sperm are first washed and placed in a sterile medium. The sperm are then concentrated in a small volume of medium and are injected into the uterus.
Which couples benefit from IUI?
Because sperm (separated from the liquid portion of the semen) are inseminated into the uterus, it is important that the female partner has no other fertility problems. Investigations should ideally show that the female is ovulating normally, has open fallopian tubes, and has a normal uterine cavity. Often, infertility tests are normal in both partners. IUI has been found to be useful in couples with no obvious cause for infertility.
IUI may also be effective in women with ovulatory disorders, provided they respond properly to fertility medications. In these situations, ovulation is stimulated by a course of treatment, such that intrauterine insemination is timed to take place close to ovulation. This technique of stimulating ovulation with hormones and introducing the sperm (commonly referred to as washed sperm) just before ovulation has proved very effective in a variety of situations and is now the preferred method in patients with or without an ovulatory disorder.
Because IUI relies on the natural ability of sperm to fertilize an egg within the reproductive tract, it is important that tests for male fertility indicate “reasonable” sperm quality in terms of count, motility, and morphology (shape of sperm). Sperm counts are usually expressed as the number of sperm per milliliter of semen. Sperm motility is the percentage of sperm that are moving. Morphology refers to the shape of the sperm and is usually expressed as the percentage of completely normal shaped sperm. Depending on the criteria used to determine if a sperm cell has a normal shape, a semen sample may be considered normal if it contains greater than 4% normally shaped sperm. When considering whether an abnormal sperm sample may succeed in achieving a successful pregnancy, some studies have suggested that a “total motile count” of 5 million is the minimum number that offers a “reasonable” prospect for a successful pregnancy. This number may be derived by multiplying the total semen volume by the sperm count by the percentage of moving sperm in the sample. For example, a sample containing 4ccs of semen with a count of 3million/cc and a motility of 20% would have a total motile count as follows:
4 x 3million x .2 = 2.4 million total motile sperm
There has been some success with IUI in patients where the female partner has endometriosis in the absence of mechanical distortion of the pelvic structures. Endometriosis is a very common disorder, particularly in women in their thirties who have not had children, and may be associated with as many as one-in-four patients with infertility. The condition occurs when tissue from the lining (endometrium) is spilled through the fallopian tubes into the pelvis, and implants on the surface of the pelvic cavity and often the ovaries. Women with mild endometriosis are often treated similarly to women with unexplained infertility.
Studies have shown that IUI will not be effective in couples where the male has a very low sperm count, very poor motility, or a very high percentage of morphologically abnormal sperm. Similarly, women with severely damaged or blocked tubes will not be helped by IUI.
How does the technique of IUI work?
The most recent studies of intrauterine insemination suggest that the best resultsare achievedwhen insemination is coupled with ovulation induced by fertility drugs. For this reason, the two procedures are often linked together as ovulation induction followed by IUI (i.e. Clomid/IUI).
Because fertility drugs can produce several eggs, careful monitoring is important during ovulation induction to assure that any side effects of treatment and/or the risk of multiple pregnancies are reduced. Monitoring of treatment is carried out by measuring estrogen concentrations in blood samples, and by following the development of pre-ovulatory follicles by ultrasound. If too many follicles develop, too many eggs may be released and thus increase the risk of multiple pregnancy. Therefore, the usual aim of controlled ovarian stimulation with IUI is to stimulate the release of 2-3 eggs.
When 2-3 eggs have reached pre-ovulatory size, ovulation is induced with a further hormone injection (hCG) to simulate the LH surge. Then shortly after (24-36 hours), around the time of expected ovulation, a sample of fresh semen is collected by the male, washed, inserted through the cervix, and placed high into the uterus of the female partner through a fine catheter. This is a painless procedure, comparable to the collection of a pap smear. It is also possible that in certain patients, a semen sample would have been collected at an earlier date and frozen for later use. At the time of IUI, it could be thawed and then similarly prepared as is done for a fresh sample.
Step-by-Step IUI Treatment
1) Drug treatment to stimulate the development of pre-ovulatory follicles (eggs)
-Usually clomiphene citrate (oral) or gonadotropins (injections) is used to stimulate the growth of follicles and cause ovulation
2) Monitoring of treatment, to assure the growth of follicles, individualized drug doses, and prevent serious side effects
-By transvaginal ultrasound scanning 1-3 times during a treatment cycle
-Measuring estrogen in a blood sample
3) Sperm sample is collected on the morning of ovulation, washed, and used for insemination later that day.
4) Pregnancy testing and ultrasound monitoring of early pregnancy
What are the potential complications of IUI?
While complications of IUI are infrequent, they include cramping after the procedure, and infection. Risks of ovarian stimulation include multiple pregnancy and Ovarian Hyperstimulation Syndrome (OHSS). Oral medication (clomiphene citrate) can cause OHSS but this is extremely rare. When hyperstimulation does occur it is usually the result of stimulation with injectable medications (gonadotropins). When this condition occurs, the ovaries rapidly enlarge and fluid may accumulate in the abdomen. Careful monitoring with blood estrogen levels and vaginal ultrasound allow for adjustments in the ovulation induction regimen, thereby minimizing the chances of OHSS.