P-217 Laboratory and clinical outcomes for fresh and vitrified-warmed oocytes after Piezo-intracytoplasmic sperm injection (Piezo-ICSI)

Abstract

Abstract Study question How is the performance of Piezo-ICSI on vitrified-warmed oocytes compared to fresh oocytes in human IVF? Summary answer Laboratory outcomes for fresh and vitrified-warmed oocytes after Piezo-ICSI were comparable. What is known already ICSI is utilized as the fertilization method for 60-80% IVF patients undergoing assisted reproductive technology (ART) worldwide. In the past 3 decades, Piezo-ICSI (Prime Tech Ltd, Japan), a refined ICSI methodology had shown increased fertilization and survival rates. The fertilization rate (2PN, 1PN, and >2PN) achieved via Piezo-ICSI was reported as high as 84-91% in previous publications. Study design, size, duration This retrospective cohort study included 12,195 fresh and 1,065 vitrified-warmed oocytes retrieved or warmed from 1334 and 93 patients respectively between January 2020 and November 2021. Mean age was 35.9 (ranged 19-49) for fresh oocytes and 27.3 (ranged 18-49) for vitrified-warmed oocytes. The vitrified-warmed oocytes were mainly originated from young donors and thus reflected in lower maternal age in this cohort Participants/materials, setting, methods All oocytes fertilized using Piezo-ICSI technology during the study period were included. Piezo-ICSI is performed using a piezo impact drive unit (MB-S; Prime Tech Ltd, Japan) driven by a controller (PMM4G; Prime Tech Ltd, Japan). The ultrathin walled micropipette (PINU06-25FT; Prime Tech Ltd, Japan) filled with 1-1.5cm operation liquid (Flourinert FC-770; Sigma, Belgium) was used for microinjection. For vitrified-warmed oocytes, Cryotec Method (Reprolife, Japan) was used for both vitrification and warming of oocytes. Main results and the role of chance The two groups (fresh and vitrified-warmed oocytes) were comparable (p > 0.05) in terms of fertilization (2PN and >2PN) rate (81.5% vs 80.0%), post-ICSI oocytes survival rate (93.3% vs 92.8), blastocyst-formation rate from 2PN oocytes (74.6% vs 71.0%) and blastocyst-utilization rate from 2PN oocytes (53.2% vs 49.3%). This study demonstrated that fresh and vitrified-warmed oocytes achieved comparable laboratory outcome following the use of Piezo-ICSI technique and ultrathin walled injection pipette. Limitations, reasons for caution The methodology in performing Piezo-ICSI differs compared to conventional ICSI, hence training is required to achieve optimal results. Wider implications of the findings Our data resonates with previously published data using the same Piezo-ICSI platform. Trial registration number Not applicable