[Comparison of two methods of cryoconservation of sperm when in very small numbers].

Objective: In case of severe oligozoospermia or following testicular biopsy in case of azoospermia, fertilization remains possible by intracytoplasmic sperm injection (ICSI). However, if there are only a few spermatozoa available to be preserved for a delayed ICSI, these gametes must be cryopreserved according to a specific method. We have found that, using the straw classical technique, less than 2 sperm were recovered at thawing when 20 sperm were frozen and no sperm were available following freezing-thawing of only 1 to 10 sperm per straw. Then, the feasibility of programmed ICSI is always uncertain in these cases and unnecessary medical acts (ovarian stimulation and egg collection) as well as patient disappointment are frequent.

Material And Methods: We have tested a new technique by introducing (with an ICSI pipette) 1 to 100 sperm in a microdrop (0.5 microl) of freezing medium setting in a culture dish under paraffin oil.

Results: Following freezing-thawing the dish, all (100%) of the frozen spermatozoa were recovered.

Discussion And Conclusion: Since only motile sperm were frozen, the sperm which are non motile after thawing (more than 50%) are nevertheless considered usable for ICSI.