Correlation between the motility of frozen-thawed epididymal spermatozoa and the outcome of intracytoplasmic sperm injection

The purpose of this study was to investigate if the outcome of ICSI was inf luenced by epididymal sperm motility in frozen-thawed specimens. A total of 18 ICSI treatment cycles using spermatozoa retrieved by microsurgical epid idymal sperm aspiration (MESA) were analysed retrospectively. Cryopreservat ion of epididymal spermatozoa was performed when enough epididymal aspirate s were collected. Sixty-nine out of 126 oocytes injected with spermatozoa r etrieved by MESA were fertilized, giving a fertilization rate of 54.8%. Out of 18 embryo transfer cycles, 6 (33.3%) achieved pregnancies. Fresh epidid ymal spermatozoa were used in 5 cycles while frozen-thawed epididymal sperm atozoa were used in 13 cycles for ICSI. The fertilization rates were 68.6% (35/51) in the former group and 45.3% (34/75) in the latter group, respecti vely. There was a significant difference between the two groups (p < 0.05). In ICSI treatments using fresh epididymal spermatozoa, the cells used for injection were all motile. However, motile epididymal spermatozoa could be used in only five ICSI treatment cycles after freeze-thawing. In 6 cycles, only immotile sperm were used for injection of frozen-thawed spermatozoa. T he fertilization rate in each group was 68.4% (13/19) and 31.6% (12/38), re spectively. There was a significant difference between these groups (p < 0. 01). These results indicate that the outcome of ICSI was influenced by sper m motility in frozen-thawed epididymal specimens. When no sperm motility co uld be recovered after freeze-thawing even with chemical treatments, consid eration should be given to retrieving fresh epididymal spermatozoa again to achieve a better fertilization rate in such patients.