Sperm Morphology: The Most Important Parameter in the Semen Analysis:

• Kruger Morphology Strict Criteria is widely accepted as the best predictor of male fertility potential, better than concentration or motility

• Low Kruger morphology has been associated with poor outcome in spontaneous conception, IUI cycles and traditional IVF. IVF/ICSI is considered to be the treatment of choice when there is poor morphology as assessed by the Kruger strict criteria

• With IVF/ICSI, poor sperm morphology has been associated with normal fertilization rates but higher rates of spontaneous abortion (Soderlund 1994; Janny and Menezo 1994; Oehninger 1988)

• Delayed fertilization and lower embryo cleavage rates have been associated with morphologically abnormal sperm (Ron-El et al. 1991)

• Sperm with abnormal morphology result in higher incidence of embryos with poor cleavage, fragmentation and overall poorer embryo morphology

• Abnormal morphology of sperm correlates with the DNA/chromatin quality; higher rates of abnormal morphology correlate with higher rates of DNA damage. DNA damage, in turn effects, embryo development, cleavage of the embryos, blastocyst formation and subsequent ability to implant successfully.

• Poor morphology of the sperm is linked to abnormal embryo development and poor implantation with subsequent early repeated pregnancy loss (S. Hammah et al. 1997, Hum Rep Update)

• Specific sperm structures, like the centrosome housed in the sperm midpiece, have been closely associated with poor embryo cleavage (von Berklom, 1995 Hum Rep Up)

• As good as the Kruger strict criteria system is, relative to other established semen assessment standards, it is imprecise in predicting live birth outcome. This is partly due to the fact that at the time of ICSI, clearly abnormal sperm (at 250x magnification) are de-selected by the embryologist prior to injection of any single sperm into the egg.

• The Kruger assessment is done at 1000x magnification thus some more subtle abnormalities seen at the time of the semen analysis are not visible that at the time of ICSI (250x magnification).

• Thus, our ability to select the morphologically best sperm is limited by the system of sperm preparation and magnification. However we now have an improved way of doing this whole process, allowing us to isolate and use the most normal appearing sperm in a sample. In this way we can take full advantage of the eggs that are ‘normal’, we are doing the best we can to not compromise the eggs with morphologically poor sperm.

• We have now instituted this process of sperm selection at SIRM St Louis. Our ability to see the amount of morphologically ‘textbook appearing sperm’ is now optimized with what we call the MSA. This is a high resolution semen analysis that tells us the most we can learn about morphology of the sperm and how we can optimize treatment with IVF/ICSI.