Debate: IMSI - Is there any scientific evidence of its value?
Before we should ask the question, if there is any scientific evidence of the value of IMSI, we should start asking whether there is any medical indication not to select good spermatozoa for injection into the oocyte? Is there any scientific evidence of choosing good sperm vs bad sperm with ICSI. Whoever is using WHO or Krueger criteria to evaluate sperm morphology believes, that sperm morphology has a value on embryo development? Otherwise, why do it? I do not know of one single publication comparing IVF or ICSI using good vs bad morphology sperm for fertilization. Would it not be time to start performing a classic prospective study on IVF and ICSI before discussing the extra benefit of IMSI, which is evident in higher number of blastocysts?
It is now well established in the literature that vacuoles only visible with the IMSI technique are closely related to disturbed chromatin condensation and DNA-fragmentation. It is one of the only therapeutic techniques applicable in the IVF lab to positively select intact sperm. The main critics against IMSI are that this technique is that expensive microscopes are necessary, it is a time consuming method and due to this point we risk oocyte aging. All these critics can be easily avoided by running a well-organized lab with motivated biologists which politics is to do the best for the patients.
Seeing that this simple non-invasive technique still raise debates and skepticism exists about its efficiency, mainly due to a low number of controlled randomized studies published yet. One fundamental question is whether we should select spermatozoa with these defects for injection if we have only to change the optics and with the knowledge that sperm vacuoles are related with abnormal chromatin packaging and possibly with DNA fragmentation? According to a recently published paper, sperm nucleus morphological normalcy, assessed at high magnification, could decrease the prevalence of de novo major fetal malformations in ICSI children. As far as we know, there is no reason for not selecting the morphologically best spermatozoa.
Furthermore, which ethical committee would give green light for a prospective randomized controlled study where purposely injection of known defective sperm with vacuoles would be necessary? If it is hard or even impossible to do prospective randomized controlled studies on ICSI comparing good vs bad sperm as good as possible, as many defects are hidden in the haziness of low magnification, how should it be possible to perform such a study with IMSI where defective spermatozoa are observable at high magnification? Who is willing to compare normal vs abnormal looking sperm, please raise your hand! And is it really necessary to conduct such a study, when observational reports show already a clinical benefit of this technique, such as an increase in the number of blastocysts obtained increasing the chance of a good expected gametes performance (EGP) and consecutive babies born, one at a time after frozen embryo-transfer with surplus embryos.
Nowadays, IMSI has to be regarded as an additional therapeutic option in the armamentarium of the very few therapeutics available in an IVF-Lab.