Intrauterine Insemination Facts: What is 'Sperm Washing?'

Posted on March 14, 2017 by NYRW

If you've researched intrauterine insemination (IUI), you've probably know the sperm sample is washed before being delivered to the uterus. You may wonder why this process is conducted. Is the sperm dirty? Does it need to be "clean" to fertilize an egg? While "sperm washing" may sound strange, it actually increases the chances of fertilization. By using a sample that contains only the strongest, healthiest sperm, you significantly increase your chances of conception. Here's how it works.

What is Sperm Washing?

Sperm washing separates sperm cells from semen, removes dead or slow-moving sperm, white blood cells, mucous and prostaglandins that may impede fertilization or endanger the woman’s health.

What are Prostaglandins?

Prostaglandins are chemicals found in the body that cause muscle contractions. They are actually responsible for cramps during menstruation and pregnancy. If raw semen that includes prostaglandins is inserted directly into the uterus (instead of first going to the cervix), a woman could experience severe pain and cramping. In some scenarios, raw semen could also cause the uterus to collapse, a severe complication.

How is Sperm Washing Done for Intrauterine Insemination?

After a sperm sample is collected from the male partner, it is subjected to one of three sperm washing techniques.

Simple Sperm Wash

The most basic method involves diluting sperm in a test tube with a solution of antibiotics and protein supplements. The sample is placed in a centrifuge where it is spun at high speed for about 30 minutes. The spinning motion causes the sperm cells to fall to the bottom of the test tube. The result is a mass of highly mobile sperm available for IUI.

Density Gradient Sperm Wash

Density gradient sperm wash takes the process a step further and separates dead cells, white blood cells and other waste products from the sperm. A test is tube filled with several layers of liquids, each with a different density. The semen sample is placed on the top layer, and the test tube is spun in a centrifuge. After spinning, healthy sperm will be collected in the bottom layer of liquid. Dead sperm and other debris will be trapped by the other layers of liquid. The process takes about an hour.

Swim Up Technique

This process ensures only the healthiest, strongest sperm are used in IUI. Semen is placed in a culture dish with a layer of media culture. Sperm are attracted to the culture and will swim up to it. They are collected as they swim up to the culture. To ensure enough sperm are collected for IUI, the process requires about two hours.

Regardless of which technique you select, sperm washing is a vital part of IUI. We’re happy to talk with you further about the process during a consultation.



American Society for Reproductive Medicine
College of American Pathologists
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Society for Assisted Reproductive Technology
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