Sperm chromatin heterogeneity as an infertility factor.

Semen samples from husbands with a history of unexplained infertility (n = 33), of women with habitual abortion (n = 36), or normal fertile donors (n = 20) were subjected to conventional semen analysis (SA), Acridine orange test (AOT), and zona-free hamster egg penetration test (HEPT). The three tests operate independently. The most discriminatory test was AOT (p = 0.0001) followed by HEPT (p = 0.019). The frequency of sperm chromatin heterogeneity as detected by AOT red fluorescence was highest in habitual abortion (39.4%), followed by unexplained infertility (16.4%), and, last, donors (9.4%). However the percentage of penetration was highest in habitual abortion (50.7%), followed by donors (43.1%), and least in unexplained infertility (33.9%). Conventional semen parameters (sperm density, motility, abnormality, and vitality) were the least to discriminate between the three groups. The presence of abnormal sperm chromatin may lead to infertility as a result of early pregnancy loss.