Manual Methods for Sperm Motility Assessment

Abstract

Progressive motility is a vital functional characteristic of ejaculated human spermatozoa that governs their ability to penetrate into, and migrate through, both cervical mucus and the oocyte vestments, and ultimately fertilize the oocyte. A detailed protocol, based on traditional manual/visual methods, is provided for performing an accurate four-category differential count including the reliable identi fi cation of rapid progressive (grade " a ") spermatozoa-the most biologically, and hence clinically, important subpopulation. Thorough prior training and the use of a microscope fi tted with a heated stage are both essential requirements for achieving accuracy and an acceptable uncertainty of measurement of no more than ±10%. Progressive motility is a vital functional characteristic of ejaculated human spermatozoa that governs their ability to penetrate into, and migrate through, both cervical mucus and the oocyte vestments (cumulus-corona complex and zona pellucida) (1). The quality of sperm progression is of far greater importance in the prediction of functional competence than either sperm concentration or percentage motility (2). When using traditional manual/visual methods, assessment of sperm progression is best achieved using a four-category differential count (3, 4) , allowing the identi fi cation of the proportion of rapid progressive (grade " a ") spermatozoa, i.e., those with a progression velocity of ³ 25 m m/s at 37°C. The importance of this is supported by evidence relating to the ability of more rapidly progressive spermatozoa to penetrate cervical mucus in vitro (5, 6) , achieve in vivo conceptions (7, 8) , and give higher clinical outcomes when using donor insemination (9) , intrauterine insemi-nation (IUI) (10) , in vitro fertilization (IVF) (10, 11) , and even intracytoplasmic sperm injection (ICSI) (12) .