IUI or Intrauterine Insemination is a broad category for donor insemination. IUI involves the injection of sperm into the uterus. The process is not painful, yet can be slightly invasive since IUI uses a catheter to enable the sperm to reach the uterus.
IUI requires the husband to supply a semen sample about 36 hours after his wife's eggs are released from her ovaries. The semen is then washed and the healthiest sperm are picked. The doctor then inserts a catheter through the cervix into the womb and then injects the sperm into the uterus.
Although not always necessary, some doctors also apply fertility drugs along side IUI treatment.