Intrauterine insemination (IUI) is a procedure in which concentrated motile sperm are deposited into the uterus through the cervix by a soft insemination catheter.
The environment of the vagina is naturally unfriendly to the sperm due to its mildly acidic environment. After ejaculation, sperm have about 1 hour to enter the cervix to continue to be viable. Conditions that can prevent entry of sperm into the uterus include poor cervical mucus or small cervical opening (cervical stenosis). Under normal condition, less than 0.1% of the ejaculated sperm would eventually reach the end of the tubes to fertilize the egg. IUI can help improving the odds by delivering millions of sperm into the more hospitable environment of the uterus while reducing the distance the sperm have to travel to reach the egg at the end of the tubes.
Intrauterine insemination can also improve conception in men with normal sperm parameters by increasing the number of sperm that make it pass the cervix. Ejaculated sperm are usually consisted of a mixture of fast and slow moving sperm, with some able to move forward and efficiently while others that can only wobble, move in circles, or not moving at all. Similar to a stalled car on the highway slowing traffics, the immotile sperm can clump together and form ‘sperm traps’ that can impede the progression of the sperm into the cervix. IUI can ensure smoother sperm traffic, bypass the cervical barrier, and shorten the distance sperm have to travel to fertilize the egg.
The cost of IUI cycle is much less than that of an IVF cycle and can vary depending on whether other treatments are also required. Ovulation induction medications and monitoring sonograms may be required in some women in order to improve the quality of ovulation and chance of pregnancy; however, these additional cost may not be necessary if there is a history of regular cycles.
At IVFMD we go through the following steps to prepare sperm for IUI:
1. Fresh semen is placed in a test tube above several layers of solutions that act as filtering barriers.
2. The tube is centrifuged to facilitate migration of motile sperm to the bottom of the tube.
3. Motile sperm accumulate in the bottom of the tube as a white pellet. The pellet is then removed and mixed in a small volume of another special solution that invigorates the sperm, extends their survival time and improves their motility. The sperm preparation (IUI Prep) is subsequently stored in an incubator up to the time of the IUI procedure. The media solution is often pink in color.
In order to get enough motile sperm for IUI, a semen sample usually must have an initial sperm concentration of at least 15 million/ml and fast motility of >15%. Lower sperm concentration or motility may not yield enough motile sperm to obtain a visible pellet for IUI to be practical.
The best chance of pregnancy is seen when at least 3 million motile sperm are available for insemination.