ObjectiveTo search for an effective method for cryopreservation of rare human sperm (RHS) by comparing the effect of RHS cryopreservation technology with that of conventional cryopreservation technology on post-thaw sperm from patients with severe oligozoospermia.

METHODSSemen samples obtained from 82 patients with severe oligozoospermia were preserved by RHS cryopreservation technology, and another 24 samples cryopreserved by conventional technology, the former divided into groups A (sperm concentration < 1×10⁶/ml, n = 54) and B (1×10⁶/ml ≤ sperm concentration < 5×10⁶/ml, n = 28), and the latter included in group C (sperm concentration < 15×106 /ml, n = 24). The survival rate of post-thaw sperm and recovery rate of progressively motile sperm (PMS) were compared among the three groups.

RESULTSThe survival rate of post-thaw sperm was significantly higher in groups A and B than in C (［62.8 ± 18.7］% and ［61.9 ± 17.2］% vs ［50.7 ± 13.5］%, P < 0.05), and so was the recovery rate of PMS (［68.7 ± 18.4］% and ［70.7 ± 15.5］% vs ［29.2 ± 12.4］% , P < 0.05), but there were no statistically significant differences between groups A and B in either of the two parameters (P > 0.05).

CONCLUSIONSThe cryopreservation technology for rare human sperm may yield relatively stable post-thaw results and deserves a wide clinical application in preserving male fertility.