In a normal sperm sample almost half of the sperm are immotile (do not swim well or do not swim at all). This means that in order to fertilize an egg via intercourse the healthy sperm must first swim past immotile sperm, travel up through the cervix and the uterine cavity, to meet the mature egg in the fallopian tube. Intrauterine insemination (IUI) is a treatment that helps to increase the chance of conception, by placing the healthy sperm directly inside the uterus.
First, the healthy sperm are isolated, washed and prepared in the lab. The sperm are then placed into a medium that promotes fertility. Finally, a small catheter is used to transfer the sperm into the uterus.
IUI has been shown to offset mild male factor infertility and to improve the chance of pregnancy in cases of unexplained infertility. It is also frequently used in combination with ovulation induction to maximize the benefits of both methods.