What is Sperm Washing?
Sperm washing, also known as sperm processing or sperm preparation, is the name given to the laboratory technique that separates sperm from seminal fluid for use in infertility treatments such as intrauterine insemination (IUI) and in-vitro fertilization (IVF). The goal of sperm washing is to separate healthy or motile sperm from unhealthy or non-motile sperm. In the case of IUI, the healthy sperm are then injected directly into a woman's uterus to facilitate union with an egg (fertilization). Semen itself is not directly injected into the uterus since it contains chemicals that can cause painful contractions or infection.
How and When Is a Semen Sample Collected?
A semen sample can be collected via ejaculation into a sterile cup, or the sample can be obtained by using a collection condom. Since it is important for the semen sample to reach the lab within thirty minutes after ejaculation, so the sample should be collected in a private setting that is nearby, or at the clinic itself.
Processing the sample can take between 30 minutes to two hours, depending on the washing technique used. Once the sample has been prepared and washing is complete, insemination is performed as soon as possible.
How is Sperm Washed?
There are two laboratory techniques commonly used to process sperm.
- The "swim-up" or "sperm-rise" method uses a layering technique, in which 2-5cc of special culture medium are placed on top of a small amount of semen in a test-tube, causing the motile or high-quality sperm to "swim up" into the culture medium. After 30-90 minutes this sperm-rich medium is then centrifuged. Centrifugation is the process that separates materials with different densities by spinning them at high speed in a machine called a centrifuge. This entire process may be repeated a few times in order to obtain more sperm. After the final wash, the sperm cells are ready for injection into the uterine cavity.
- A more sophisticated method of separating motile sperm from unhealthy sperm is "Density Gradient Separation." This process provides the best recovery of healthy sperm and is especially recommended for samples of poor quality sperm. Using a dense liquid solution, the lighter immotile sperm and debris separate from the motile sperm, which sink to the bottom of the test tube. After centrifugation the collected sperm cells can be used for IUI.
Washed Sperm Count Needed for IUI
For IUI to succeed, it is estimated that a count of over one million washed sperm is necessary. When the sperm count is less than 5-10 million, resulting pregnancy rates are significantly lower. Conversely, success rates are higher with washed counts of over 20-30 million, although counts of over 50 million do not seem to offer significant advantage.
Completing the IUI Procedure
After sperm washing or preparation is complete, the sperm concentrate is injected through the cervix into the uterus by means of a thin, flexible catheter. The actual insemination process takes only minutes.
Women may experience mild but temporary cramping during the process. While they can resume their regular activities the same day, women should be aware that there is a small (less than one percent) risk of infection following IUI. If women notice any symptoms such as fever, chills, pelvic or abdominal pain, they should contact their physician immediately.