Clinical significance of the Acridine Orange test performed as a routine examination: comparison with the CASA estimates and strict criteria

The aim of the present study is to clarify the clinical significance of the Acridine Orange (AO) test (a sperm function test) as a routine examination by investigating the relationships between chromatin decondensation assessed by the AO test and routine semen analysis. Totally 543 semen samples were obtained from 286 infertile men. The AO test was performed, and spermatozoa displaying green fluorescence were considered as mature. The threshold of green AO fluorescence as 50% was adopted and the values <50% were considered as positive in the test. Computer-aided sperm analysis (CASA) and strict criteria were used for routine semen analysis. Twenty-two (4.05%) of 543 semen samples were positive in the AO test. In 20 semen samples obtained from men with severe male infertility treated by intracytoplasmic sperm injections (ICSI), the positive rate was 30.0%, which was significantly higher than that (2.63%) treated by conventional in vitro fertilization (IVF) (p=0.01). As for the basic sperm parameters, there were significant correlations between the AO test and sperm motility (p<0.001), and between the AO test and normal sperm morphology (p=0.02). However, there was no relationship between the AO test and sperm concentration (p=0.585). Sperm motion parameters assessed by CASA, including amplitude of lateral head displacement (ALH), curvilinear velocity (VCL) and rapid sperm movement (Rapid), were significantly correlated with the AO test. The information obtained using the AO test was indicated to be useful in planning treatment strategy for infertile couples.