THE HYPOOSMOTIC SWELLING TEST FOR SELECTION OF VIABLE SPERM FOR INTRACYTOPLASMIC SPERM INJECTION IN MEN WITH COMPLETE ASTHENOZOOSPERMIA

Objective: To determine the ability of the hypo-osmotic swelling test to select viable sperm from nonmotile sperm samples for intracytoplasm ic sperm injection (ICSI). Design: Nonrandomized, sequential comparati ve study. Patients: Thirteen couples enrolled in our ICSI program had 16 cycles in which sperm preparations with 0% motility were obtained. Five cycles used cryopreserved epididymal sperm with complete asthenoz oospermia. Interventions: In eight cycles, the semen samples were wash ed through a Percoll gradient and sperm mere selected randomly for ICS I. In another eight cycles, the washed sperm were placed in a hypo-osm otic solution (75 mM fructose; 25 mM sodium citrate dihydrate) and the sperm with curled tails taken up with the microinjection needle, rins ed, and used for ICSI. Main Outcome Measures: Fertilization rate per o ocyte injected as determined by the presence of two pronuclei at 18 ho urs after retrieval and embryo cleavage rate per oocyte injected at 48 hours after retrieval. Results: With random sperm injection, the fert ilization and cleavage rates were 26% and 23%, respectively. In contra st, after injection of sperm selected using the hypo-osmotic swelling test, fertilization and cleavage rates were significantly greater (43% and 39%, respectively). There were three pregnancies in the eight-cyc les with the hypo-osmotic swelling test-selected sperm, including two from frozen epididymal sperm. Conclusion: Based on these preliminary o bservations, we believe that the hypo-osmotic swelling test will prove to be valuable for increasing fertilization and cleavage rates and pr egnancy rates in ICSI cycles where no motile sperm are recovered.