Evaluation of sperm morphology using Kruger's strict criteria

Prospective and retrospective studies were conducted to evaluate sperm morphology using strict criteria for predicting fertilization capacity in males. Severely impaired male fertility potential was measured by a result of less than or equal to 4% (denotes percentage sperm having normal morphology) and scores of greater than 14% indicated normal fertilization potential. There were no statistically significant differences found in pregnancy rates in partners of men with normal morphology of less than or equal to 4% vs. those with 14% or greater (chi 2 analysis): the prospective study showed a 41% pregnancy rate in less than or equal to 4% group vs. 29% rate in greater than 14% group (p = 0.44 NS); the retrospective analysis showed a 50% pregnancy rate in the group with less than or equal to 4% morphology scores vs. 67% in greater than 14% group (p = 0.45 NS). When only the men with normal motile density (greater than 10 x 10(6)/ml) were evaluated, a statistical difference was found in the retrospective study between the group with morphology results greater than 14% (93%) vs. the group less than or equal to 4% (40%). However, the 56% success rate in the men with less than 10 x 10(6)/ml sperm and normal morphology less than or equal to 4% reduces the significance of the diagnosis of sperm morphology using the new strict criteria.