O-184 Piezo-ICSI reduces oocyte degeneration, improves ICSI success rates and has shown less dependence on the experience level of embryologists: cumulative data with 65,033 MII oocytes
Authors: Watanabe H , Nakagawa K 
Published: July 2024

Abstract

Study question
Dose piezo-ICSI improve the overall success rates of in ICSI operations compared with the conventional ICSI by the operators with different level of experience?

Summary answer
Piezo-ICSI showed lower oocyte degeneration rate during or after ICSI operations compared to the conventional ICSI for embryologists with different level of experience.

What is known already
Intracytoplasmic sperm injection (ICSI) with a glass micropipette can sometimes result in degeneration of the injected oocyte. Piezo-assisted ICSI has been developed as an alternative method to prevent such degeneration occurring during the procedure. It employs gentler and controlled impacts generated from the piezo electric elements attached to the injection micropipette holder to penetrate oolemma, and it does not require reciprocal aspiration of ooplasm required in the conventional ICSI. While there have been numerous study reports demonstrating the improvements in fertilization rates with piezo-ICSI, most of these studies have the limitation in the size study of population.

Study design, size, duration
We conducted a retrospective analysis of the ICSI results with 65,033 MII oocytes in 15,687 treatment cycles carried out between January 2018 and February 2023. ICSI were performed using the piezo-assisted equipment with flat-tip micropipettes (PIEZO PMM4G, Prime Tech Ltd., [n = 51,484, Piezo-group]) or in the conventional ICSI method with spiked-tip micropipettes (n = 13,549, C-group).

Participants/materials, setting, methods
Following the insemination with ICSI, the oocyte degeneration rate, fertilization rate per MII oocytes and blastocyst formation rate per 2PN embryos were evaluated in both the Piezo- and C-groups (n = 51,484 and n = 13,549, respectively). We also evaluated the degeneration rates and fertilization rates of ICSI by the operators: i.e., well-experienced embryologists (at least 10 years of experience) and less experienced embryologists (5 years or less of experience).

Main results and the role of chance
The fertilization and blastocyst formation rates in the Piezo-group were 83.8% (43,140/51,484) and 54.0% (23,300/43,140), respectively, which were significantly higher than the C-group (74.8% [10,132/13,549] and 36.6% [3,674/10,132], respectively, p &lt; 0.01). The oocyte degeneration rate in the Piezo-group was 2.9% (1,493/51,484), which was significantly lower than the C-group (6.9% [933/13,549], p &lt; 0.05). For the patients over 40 years old, the degeneration rate was also significantly lower in the Piezo-group (3.0% [632/20,770]) than the C-group (7.1% [351/4927], p &lt; 0.01), while the fertilization and blastocyst formation rates were higher in the Piezo-group (82.6% [17,164/20,770] and 46.6% [7,997/17,164], respectively) than the C-group (72.8% [3,588/4,927] and 25.8% [926/3,588], respectively, p &lt; 0.01).
We found a marked drop in the oocytes degeneration rates in the Piezo group recorded from both well-experienced and less experienced embryologists. The degeneration rates recorded by less experienced embryologists were 2.8% (119/4,242) in Piezo-group and 8.6% (8/93) in the C group (p &lt; 0.01), while the records by well-experienced embryologists were 2.7% (815/29,681) in the Piezo-group and 6.9% (555/8,037) in the C-group, respectively (p &lt; 0.01). The fertilization rates of the Piezo-group by less experienced and well-experienced embryologists were 84.1%(3,569/4,242) and 83.4% (24,757/29,681), respectively, which were significantly higher the C-group (71.0％ [66/93] and 76.7％ [6,167/8,037], respectively, p &lt; 0.01).

Limitations, reasons for caution
It is a retrospective study, in which the ICSI operations with piezo and the conventional methods were not equally assigned to the embryologists, especially, for those less experienced, thereby the number of conventional ICSI operations was more skewed to well-experienced embryologists than the less experienced colleagues.

Wider implications of the findings
Our results with piezo-ICSI showed a marked drop in the oocyte degeneration while achieving comparable fertilization rates amongst operators with different levels of experience. We found these as major advantages over the conventional method in standardizing the ICSI operation by filling the gap between embryologists with different length of carrier.

Trial registration number
Not applicable