Reacción a "Reactions: Ultrasounds increase sperm mobility by 266%"

Assisted reproduction techniques have been improving their outcomes since the birth of the first baby in England in 1976, but in recent years, we have seen how this progressive improvement has stalled despite the incorporation of advanced and costly technologies in our laboratories. We have managed to increase our predictive capacity and improve the study and diagnosis of the embryos we obtain in in vitro fertilization cycles, but without substantially increasing the pregnancy options for our patients. We know very well what a good embryo should be like and we identify it, but we still have a long way to go to know how to improve the quality of those embryos.

That's why lately the focus has been turning towards the development of new basic laboratory techniques that allow us better treatment and processing of gametes, both eggs and sperm, and this work would fit perfectly into this approach.

In this sense, logic suggests that an increase in sperm motility should be important within a reproductive process, but it has not really been seen to be so decisive when applying in vitro fertilization techniques.

In practice, we have been able to verify that there is not such a direct relationship between motility and fertilizing capacity, and often we encounter normal sperm, with good motility, that are not capable of fertilizing the egg; while others, with poorer motility, have no problem doing so.

The explanation lies in the fact that there are other factors involved in the process with equal or even greater importance, such as the interaction between membrane proteins existing in the sperm head and in the zona pellucida of the egg, a point that is not considered in this study.

A separate issue would be that of men with completely immobile sperm (severe asthenozoospermia) or those obtained through testicular biopsy since, often, in these cases sperm motility is practically zero, which does not allow distinguishing viable sperm from dead ones, increasing the risk of total failure of egg fertilization in the case of using the latter. The possibility of activating such motility through ultrasound (in 33%), as indicated by the authors, would allow selecting viable sperm, thereby improving fertilization rates in these situations.

In conclusion, as with any laboratory improvement, it is important to objectively define the cases in which the technique may clearly be indicated. In situations of severe absence of sperm motility, it could serve us to easily distinguish viable sperm from non-viable ones, but it remains to be shown whether this increase in motility actually translates generally into an increase in egg fertilization rates and better embryo quality.