“Sperm washing” is the common name for the semen processing technique used to select sperm. How is “sperm washing” done? Which is closer to “fruit washing” or “card washing”? In fact, it’s not. Let’s take a look at what “sperm washing” in IVF is all about. “Sperm washing”, mainly used in assisted reproductive technology IVF treatment and artificial insemination treatment, is a certain procedure to select sperm, that is, to select mature, active sperm with fertilization potential. The ideal technique for semen processing should include simple and fast operation without causing sperm damage and removing dead sperm and other cells such as white blood cells and bacteria whenever possible. The more common method used in our center is density gradient centrifugation. The principle is that live sperm, dead sperm, leukocytes and bacteria have different settling coefficients and will have different settling speeds under certain centrifugal forces, forming zones in different gradient solutions. The approximate procedure is shown below: Of course, the density gradient centrifugation method is not suitable for patients with very severe oligospermia or patients with surgical puncture for sperm extraction. In addition to the density gradient centrifugation method, depending on the form of sperm retrieval and the quality of semen, direct upstream methods, centrifugation followed by upstream methods, and direct sperm finding in high magnification field of view may also be used. So, this is how “sperm washing” is done, and I have mastered a new use of “washing”!