To diagnose a sperm sample as teratozoospermic, today labs use the WHO's criteria, which indicate that a man has teratozoospermia if more than 96% of sperm are abnormally shaped.
However, some labs continue using Kruger's strict criteria to evaluate sperm morphology. According to Kruger's, a man is teratozoospermic if more than 85% of the sperm are abnormal.