The application of assisted reproductive techniques (ART) has revolutionized the treatment of infertility. With ART, semen samples must first be processed before they can be used for insemination. Sperm preparation methods seek to replicate in vitro the natural process in which viable sperm are separated from other constituents of the ejaculate as they actively migrate through the cervical mucus. An ideal sperm processing technique should be gentle and one that recovers a highly functional sperm. Various sperm separation or isolation methods include swim-up methods, two-layer discontinuous gradient centrifugation, pentoxifylline wash, test-yolk buffer, sedimentation methods, polyvinylpyrrolidone (PVP) droplet swim-out, electrophoresis and fluorescence cell sorting methods. Retrograde ejaculation occurs when semen is directed into the urinary bladder during ejaculation.