Success through quality

Sperm selection

It is owed to the substantial progress in Assisted Reproductive Technologies that a successful treatment outcome may be achieved for couples who, in the past, had no prospect of success due to an extremely poor sperm test.

Years ago, a method referred to as Intracytoplasmic Sperm Injection (ICSI) has become a milestone in infertility treatment. With the aid of this technique, a single sperm can be injected directly into the cytoplasm of an oocytein order to achieve fertilization.


Our biologist, Dr. Pierre Vanderzwalmen, is a pioneer in this field and has made a major contribution to establishing this method.

The enhancement of the ICSI-procedure is referred to as "Intracytoplasmic Morphologically Selected Sperm Injection" (IMSI procedure).

For conventional ICSI, spermatozoa are selected at 200-400-fold magnification. The IMSI procedure allows a far better assessment, since spermatozoa are selected at high magnification (6000 – 12.500-fold).

For comparison: Just imagine watching the surface of the moon by merely using a pair of binoculars. Whether you use opera glasses or the Hubble Space Telescope makes all the difference.

Due to the novel IMSI technique it has been shown that even in the case of “normal” sperm tests there are still differences in quality that can’t be identified and evaluated by ICSI.

On average, 50 % of all spermatozoa are showing poor quality. The poorer the sperm test, the less spermatozoa of good quality can be identified. With the help of the IMSI procedure we were able to establish a novel classification scheme for spermatozoa (sperm quality 1 - 4).

Using grade 1 – 2 sperm for fertilization (compared to using grade 3 – 4 sperm) has led to a significant increase in the number of embryos reaching the blastocyst stage by day 5.


Interestingly enough, this correlation is not clearly evident on day 3 of embryonic development. This may be explained by the fact that the “late paternal effect” can become manifest as early as day 3 of embryonic development.

Late Paternal Effect

To this end, we must conclude that, in addition to choose the best blastocyst, it is crucial to perform sperm selection as well.

Final conclusion:
As already mentioned, 50 % of all spermatozoa are of poor quality. Using such sperm for fertilization will only rarely result in the development of a blastocyst.

Our theoretical considerations are as follows:
Assuming that in 50 % of all cases the wrong sperm is selected for fertilization by performing conventional ICSI (the assessment of defects in sperm heads is rather difficult), we are at risk that e.g. in a 38 year old woman one of two oocytes cannot utilize its “development potential”.

Thus, pregnancy rates and baby-take-home-rates will be halved within this age group by applying only the ICSI technique instead of the IMSI procedure.

We have carried out and published detailed scientific investigations on this issue that strongly support our conclusions.

New figures imply that the IMSI method is also superior to conventional IVF. The question arises as to whether the oocyte is capable of detecting sperm head defects (even sperm that seems to be morphologically normal may present severe head defects with large vacuoles when evaluating sperm morphology by the IMSI technique).

Literature on the subject

   Pub Med

     Blastocyst development after sperm
       selection at high magnification is
       associated with size and number
              of nuclear vacuoles.

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