Intrauterine insemination (IUI) is a fertility treatment where sperm are placed directly into a woman’s uterus. During natural conception, sperm have to travel from the vagina through the cervix, into the uterus, and up to the fallopian tubes. With IUI, sperm are “washed” and concentrated, and also placed directly into the uterus, which puts them closer to the egg.IUI is a relatively painless and noninvasive procedure. IUI is sometimes done in what is called the “natural cycle,” which means no medications are given. A woman ovulates naturally and has the sperm placed at a doctor’s office around the time of ovulation.