The Usefulness of Sperm Viability Testing in Reproductive Technology: The Hypo-Osmotic Swelling Test, Laser and Motility Stimulants
The Scientific and Biological Bases of Testing Sperm Viability
It is commonly accepted that the standard World Health Organization (WHO) criteria for sperm number, motility, and morphology are a good, although not always perfect, indication of a male’s fertility status. The current criteria1 have recently been changed from the 1999 to 2010 WHO recommendations, whereby semen volume (2-1.5 mL), sperm concentration (20-15 million per mL), progressive motility (505%-32%), and normal forms (14%-4%) have all been decreased, respectively. Although the current criteria suggest a certain volume, number, motility, and morphology, it must be emphasized that this is an indication that the male may have difficulties to father a child rather than predicting fertility.
Fortunately, the majority of these males that fall below these semen parameters will conceive even though it may take longer or they will need assistance through one of the assisted reproductive technology methods. Some, however, will be diagnosed with extremely low or absolute asthenozoospermia, and even with the assistance of intracytoplasmic sperm injection (ICSI) it becomes difficult to treat this condition.
These extreme cases of ICSI where there are no motile spermatozoa, extremely few motile spermatozoa, only twitching spermatozoa, or when sperm numbers are extremely low now represent the most challenging treatment situations. The advent of no motile spermatozoa may arise due to a number of scenarios not excluding immotile cilia syndrome, which is thought to be present in approximately 1 in 5000-6000 men.2-3 More frequently, the presence of no motile spermatozoa will arise after sperm are extracted from the testes or epididymis or after a low-quality sample is frozen and thawed.
Along with the presence of no motile spermatozoa is also the inability to distinguish if those spermatozoa are in fact viable or dead. It is well accepted that the arbitrary selection of an immotile spermatozoon and attempt at fertilization by ICSI will provide significantly lower chances of success.4-8 The challenge, however, is how to treat these men, indeed the question is, “When an ICSI technician is deprived of the chance to choose a motile spermatozoa how does he/she find a live sperm?” This chapter discusses the various options that allow in vitro fertilization (IVF) clinics to improve the chances of success for couples in which the male has extremely poor sperm parameters that limit the chance of selection of a viable sperm.