Prior to placement in the uterus (Artificial Insemination), it is beneficial to separate motile sperms from the remainder of the semen specimen.
This procedure uses a two-layer density gradient technique to separate motile sperms from the seminal constituents, which includes non-motile sperms, debris, seminal fluid, white blood cells and bacteria.
Before the insemination, the male partner collects a semen specimen at the laboratory or at home. Following collection, the specimen is allowed to liquefy at room temperature.

The liquefied specimen then is layered onto a specially prepared density gradient. The density gradient is made up of two increasingly dense layers of a liquid, which contains suspended micro-particles that act as a liquid filter. The layered tubes are placed in a machine that spins the layered tubes at a very high speed.

The centrifugal force created by the spin encourages motile sperms to migrate out of the seminal constituents and concentrate into a pellet at the bottom of each tube. The seminal constituents and gradient layers are removed and discarded. Then the remaining pellet of motile sperms is washed two times to remove the remaining density gradient.

Following the final wash, the sperms are re-suspended into a small volume used for the insemination. The procedure takes approximately half an hour.