ABSTRACT
The clinical usefulness of the strict Tygerberg criteria for sperm morphology evaluation1 for in vitro fertilization outcome and later for in vivo pregnancies has been demonstrated by Kruger et al.2,3 and Van Zyl et al.4, respectively, and thereafter has been confirmed in many publications5. However, even in the presence of the so-called Ppattern or in the poor-prognosis group (≤4% morphological normal forms), some men achieve fertilization of oocytes in vitro, and in vivo pregnancies occur occasionally3,5. Therefore, efforts to develop more sensitive predictors, especially for expected in vitro fertilization rates, are continuously being put forward. Some of these predictors are based on sperm biochemical tests such as the sperm chromatin dispersion test6, the sperm chromatin structure assay7 and the ubiquitin-based sperm assay8, while others incorporate a combination of semen variables, for example the post-wash total progressively motile cell count9, or have refined certain existing semen variables such as sperm morphology by the use of more specific sperm morphology parameters, namely the sperm deformity index10 or the spontaneous acrosome reaction as seen with Spermac staining11.
