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Intracytoplasmic Injection of Testicular Sperm Results in Higher Fertilization Rates than Ejaculated Sperm from Oligoteratozoospermic Males.

This research presented at the American Society for Reproductive Medicine (ASRM), San Diego, 2000.

CA Adams, LS Anderson, PG Wise, SH Wood. Reproductive Sciences Center, La Jolla, CA, USA.

Objective: To compare the fertilization, pregnancy and implantation rates of couples undergoing ICSI with testicular sperm extraction (TESE) versus couples with severe male factor infertility using ejaculated sperm for ICSI. Design: A retrospective analysis of ICSI cycles performed between 1997 and 1999. Materialsand Methods: The results from 21 TESE/ICSI procedures were compared with a subgroup of 25 ICSI cycles with severe oligoteratozoospermic males using ejaculated sperm (median values for sperm count, motility, and normal morphology using Kruger's strict criteria were: 7x 106 / ml, 40 % and 2 %). Testicular sperm was retrieved by fine needle aspiration (19 g butterfly), 3-24 hours prior to ICSI, from 17 obstructive and 4 non-obstructive patients. Testicular tubules were finely minced and supernatant processed on 3-layer mini-density gradients. After 2x wash, testicular sperm was resuspended in microdrops of HTF + 5% HSA under oil and incubated at 37¡C in 5% CO2. Immediately prior to injection, motile or twitching sperm were collected into a drop of media, then placed briefly into 10% PVP and selected for injection. All ICSI procedures were performed by the same embryologist, 3-6 hours after oocyte retrieval, using standardized techniques. Embryos were transferred from day 2-5. Statistical analyses used the unpaired t-test. Results: There was no significant difference between the means of patient age (34 yr.), number of oocytes retrieved, number of oocytes injected, and number of embryos transferred (3.5) for the two groups of couples (testicular versus ejaculated sperm). The mean 2PN fertilization rate with testicular sperm was 76%, significantly higher than for the oligoteratozoospermic group (56%; P< 0.05). (These compared with an overall ICSI 2PN fertilization rate during this period of 65%.) Pregnancy and implantation rates were the same for the TESE/ICSI and oligoteratozoospermic groups (52% and 22% respectively). Conclusion: Previous studies have shown that normal fertilization rates with ICSI using testicular sperm are generally lower than with ejaculated sperm. In contrast to these results, our data indicates that higher fertilization rates may be achieved with testicular sperm. A possible cause of the high fertilization rate achieved with testicular sperm is that the majority of the TESE patients had obstructive azoospermia, in which spermatogenesis is normal. Sperm extracted from these patients may have a higher fertilization potential than ejaculated sperm from severe male factor patients. In addition, improved protocols used during the processing and injection of testicular sperm (e.g. separation on a density gradient, incubation of processed sperm prior to injection and minimal exposure to PVP) may increase its fertilizing capability.