Evaluation of Sperm Morphology Using Kruger's Strict Criteria

Abstract

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 ≤4% (denotes percentage sperm having normal morphology) and scores of > 14% indicated normal fertilization potential. There were no statistically significant differences found in pregnancy rates in partners of men with normal morphology of ≤4% vs. those with 14% or greater (x² analysis): the prospective study showed a 41% pregnancy rate in ≤4% group vs. 29% rate in > 14% group (p = 0.44 NS); the retrospective analysis showed a 50% pregnancy rate in the group with ≤4% morphology scores vs. 67% in > 14% group (p = 0.45 NS). When only the men with normal motile density (>10 × 10⁶/ml) were evaluated, a statistical difference was found in the retrospective study between the group with morphology results >14% (93%) vs. the group ≤4% (40%). However, the 56% success rate in the men with <10 × 10⁶ /ml sperm and normal morphology ≤4% reduces the significance of the diagnosis of sperm morphology using the new strict criteria.

Key Words:

• Fertilization
• Morphology
• Sperm