Intrauterine inseminations are predominantly suggested for subtle male factor infertility (to place the sperm under the fallopian tubes so that they have less barriers to cross and a shorter distance to travel to meet the mature egg within the fallopian tube) or an abnormal sperm mucus interaction (a pelvic factor that can be assessed with the postcoital test).
If abnormal sperm is identified without a specific cause, treatment options include intrauterine insemination (IUI), controlled ovarian hyperstimulation with IUI, and IVF with ICSI. For mild to moderate male factors, I typically recommend a progression through the available treatment options from less aggressive to more aggressive (until a pregnancy is achieved). If there is a marked abnormality in the semen analysis I may recommend that the couple initiate treatment at a more aggressive level with controlled ovarian hyperstimulation with IUI or IVF with ICSI.
If an abnormal postcoital test is identified, IUI is a simple and relatively inexpensive way to place the motile sperm above the apparent cervical (mucus) barrier at the time of ovulation. Ovulation is usually predicted in these natural cycles by using an ovulation predictor kit or an ovulation monitor. I generally do not suggest “fixing” the hostile sperm mucus interaction since I have not had good success with available treatments. It also usually takes a long time (months) to determine whether treatment is effective (effectiveness of a treatment generally requires reassessment of the mucus in a subsequent menstrual cycle).
There appears to be a significant reproductive advantage for sperm that is placed within the uterine cavity. When sperm are deposited “naturally” during intercourse into the vaginal vault there is reportedly a very rapid dropoff in the number of sperm as they move from the vagina toward the fallopian tube. If about 50-500 million sperm are placed within the vaginal vault during intercourse (where they normally live for less than 1-2 hours), then only about 1 million sperm find their way to the “friendlier” cervical mucus (where they normally can live for a few days), only a few thousand sperm eventually find their way to the top of the uterine cavity where the tubal openings are located, and only hundreds to thousands of sperm enter the tube in search of a mature egg. The mechanism for this tremendous dropoff of sperm along the way to the tube is not fully understood.
Intrauterine insemination is a procedure that usually places more than 1 million motile sperm (many men with decreased sperm counts will have greater than 1 million motile sperm per ejaculate) at the top of the uterine cavity near the opening of the tubes (where only a few thousand motile sperm normally make it) to improve the ability of those sperm to enter the fallopian tubes and fertilize a mature egg.
The success of these procedures that attempt to optimize the sperm’s natural fertilizing ability is apparently limited by the inherent sperm quality. When equal numbers of motile sperm are separated from semen that initially has a normal semen analysis versus semen that initially has a poor semen analysis, there appears to be better fertilization and pregnancy rates with the sperm from the normal sample.
The exposure to risk with intrauterine insemination is small.
There is an underlying risk of uterine perforation (making a hole in the wall of the uterus) with the insemination catheter, but the catheters that are currently available are generally quite soft and flexible (so this risk is minimal).
There is a risk of infection with insemination from bacteria that either originated within the inseminated semen sample or was introduced (during the preparation process) into the insemination sample. Inert buffered media used to wash sperm often contains antibiotics (eg., penicillin and streptomycin) to limit this risk of infection-- and the overall risk appears to be quite small. For example, in my own practice I have never seen an infection introduced at the time of insemination.
There is a risk of localized trauma to the endometrium (uterine lining) and subsequent bleeding with insemination. The endometrium is very delicate (friable) and introducing a catheter into the uterine cavity certainly could create a “groove” in this lining and result in a small amount of bleeding. A small amount of flow following intrauterine insemination is not known to reduce the pregnancy rate for that insemination and has no known longer term risks.
There is a risk of discomfort with the insemination procedure. Introduction of the insemination catheter into the uterine cavity may produce a uterine cramp (contraction) simply due to the presence of a foreign body (the catheter) in the uterus. Also, if there is any semen that has not been completely washed from the inseminated sperm sample then this can cause a contraction if placed within the uterus.