Assessing the clinical value of the Kruger strict morphology criteria over the World Health Organization fourth edition criteria

The Kruger WHO5 and WHO4 morphologic criteria correlate closely. Only two men (0.4%) with an abnormal Kruger morphology had normal WHO4 morphology. Given the limited predictive value of sperm morphology, the additional cost and effort of Kruger criteria may not be warranted in lieu of, or in addition to, the WHO4 classification.