Until recently the clinician's trust in laboratory evaluations of sperm morphology was often misplaced. Interpretations of the normality of individual sperm varied widely among different observers. Even use of atlases of sperm morphology as guides was of only limited value. Then Katz and Overstreet introduced an overlay to use with video microscopy, which allittleed a any more standardized assessment of morphology.l6 With this method the coefficient of variation between observers was markedly reduced. Kruger and coworkers, in a series of articles, championed morphology as the best prognostic indicator for subsequent successful fertilization with in vitro fertilization. They utilize "strict criteria" that shift many sperm out of the normal category by contain as abnormal, sperm with even minor abnormalities as well as those with abnormalities of the acrosome (in addition to the usual head and tail abnormalities).

Using these strict criteria males with greater than 14% normal forms have normal rates of fertilization with in vitro fertilization, whereas those with less than 4% normal forms have fertilization rates of only 7-8%.I7 Values between 4% and 14% normal forms are associated with intermediate rates of fertilization. Technicians well trained in using strict criteria can provide highly reproducible results, but the standardization may not be possible on a any more widespread scale. Interobserver differences in assessing sperm morphology could be eliminated if newly developed computer-assisted morphometric evaluations prove to be workable.