A novel micro-straw (LSL straw): the reliable cryopreservation vehicle for rare or very low concentrations of human sperm (83 cases reported)

Objective To analyze the pregnancy outcome of cases who underwent intracytoplasmic sperm injection (ICSI) with frozen-thawed sperm, which was rare and weak, cryopreserved by a novel micro-straw (LSL micro-straw). Methods The present study retrospectively analyzed the post-thaw results of cryopreserved human sperm from 83 severe infertility male patients (including oligospermia and asthenospermia). Then we investigated the evolution of embryo development and pregnancy outcome in 23 patients underwent ICSI. Results About 89.5% (94/105) frozen-thawed samples could observe motile sperm in quality control. About 73.9% (17/23) sperm were available in 18 ICSI cycles. The fertilization rate, the cleavage rate, the available embryo rate and the high-quality embryo rate were 78.0%, 92.5%, 62.7% and 78.0%, respectively. The implantation rate, the clinical pregnancy rate and the cumulative live birth rate were 31.1%, 52.5% and 55.6%, respectively. Totally 12 live births were obtained with no birth defects reported. Conclusion LSL micro-straw is a safe and feasible new carrier for cryopreservation of oligospermia and asthenospermia, which can be widely applicated in assisted reproductive technology. Key words: Rare human spermatozoa; Freezing and thawing; Novel micro-straw (LSL micro-straw); Intracytoplasmic sperm injection (ICSI); Pregnancy outcomes