Are my spermies germy? Why do we wash semen before an IUI?

Your partner has been instructed it is time for her IUI and you are on deck to produce a sample. You hear the words “you need to produce a sample” and “we need to wash the sample before we can use it” and think to yourself “My sperm need WASHED? How dirty are they?”

While it sounds like we are saying that the sperm needs a good cleaning up, washing the sperm doesn’t mean that the sperm are dirty. It simply means that we are separating the good sperm from the seminal fluid. Seminal fluid needs to be removed prior to IUI because 1) it contains debris, white blood cells and dead sperm cells, which can produce oxygen radicals that can impair fertilization of the egg. 2) it also contains prostaglandins, which can cause intense and painful cramping. 3) bacteria in the seminal fluid can lead to infection. These are the reasons why raw semen is never used for IUI! When ejaculated into the vagina, these components are naturally prevented from entering the cervix and getting through to the uterus.

Now for some technical stuff. There are two commonly used sperm preparation techniques – swim-up and discontinuous density gradients.

Swim-up

Specific medium is gently layered over semen in a sterile conical-based centrifuge tube. The tube is inclined at an angle of 45 degrees and incubated for 1 hour at 37⁰ C. It is then gently returned to the upright position and the upper layer removed. The upper layer of motile cells is then diluted with a large volume of medium,, centrifuged at 500g for 5 minutes, and finally resuspended in 0.5 ml of culture medium for IUI.

Discontinuous density gradients

This is the preferred technique at InVia fertility Specialists. It utilizes a density gradient to isolate and purify the motile sperm. When a semen sample is placed upon the gradient layer and centrifuged, any debris, cells, non-motile, and poor quality sperm remain in the top layers. The motile sperm are able to get through the gradient layer and concentrate at the bottom of the test tube. This makes for a highly concentrated, purified sample for IUI. Sometimes, it is necessary adding a swim-up procedure for having a best sample.

Both techniques are equally effective with no difference in the pregnancy or miscarriage rates.