Intrauterine insemination is often an important part of treatment for couples that are infertile due to sperm disorders. IUI involves injecting sperm through a narrow catheter into the wife’s reproductive tract. For most couples, artificial insemination is performed with the husband’s sperm. Depending on the husband’s sperm count and motility, the wife’s cervical mucus quality at the fertile time of her cycle and the estimated time to egg release from the ovarian follicle, a well-timed IUI can be very effective. In a laboratory, the sperm can be separated from the seminal fluid and re-suspended in a very small volume of sterile medium that will keep the sperm alive and actively mobile. Often, preparation involves a “swim-up” procedure, in which only the fastest swimmers are selected for insemination. The insemination is performed by passing a sterile catheter through the cervical canal into the uterine cavity and then injecting the sperm suspension into the uterine cavity. Usually the insemination itself causes little if any discomfort.