P-125 Relationship between ooplasmic fluidity and oocyte degeneration examined by image analysis after Piezo-intracytoplasmic sperm injection (ICSI)
Authors: Morimoto T , Matsubayashi H , Takeuchi T , Ishikawa T , Haraguchi R 
Published: July 2024

Abstract

Study question
Can image analysis of ooplasmic fluidity in Piezo-ICSI predict unintentional membrane rupture (UMR) and subsequent oocyte degeneration?

Summary answer
Image analysis of ooplasmic fluidity using “optical flow” can be used to predict UMR and subsequent oocyte degeneration in Piezo-ICSI.

What is known already
UMR during Piezo-ICSI sometimes leads to oocyte degeneration, but not all oocytes degenerate. Leakage of ooplasm is often observed in degenerating oocytes after Piezo-ICSI. We speculated that the occurrence of ooplasmic leakage could relate to the ooplasmic fluidity. Optical flow is an image processing algorithm that analyses the movement of an object in a motion picture. In this study, the motion vectors for all pixels in the image were calculated using the dense optical flow method.

Study design, size, duration
We developed an image analysis system that detects the movement of the ooplasm on Piezo-ICSI videos using the OpenCV library. Videos of 96 oocytes recorded during Piezo ICSI (mean maternal age: 39.2±5.4 years) retrieved in our institute between January 2020 and September 2023 were retrospectively analyzed using the system. To minimize the potential influence of technical factors, Piezo-ICSI was performed by two embryologists.

Participants/materials, setting, methods
The oocytes were characterized by survival or degeneration and labeled with and without UMR. To evaluate the ooplasm fluidity, we analyzed the vertical motion vectors of all pixels between the start to puncture and the rupture of the oolemma (1st period) and between sperm injection and withdrawal of the pipette (2nd period). The velocity between groups was compared at the 95th, 99th, and 99.5th percentiles, followed by statistical analysis by the Mann-Whitney U test.

Main results and the role of chance
The 95th, 99th, and 99.5th percentiles of the survival group (n = 75) were significantly higher than those of the degeneration group (n = 21) in the 1st period (P &lt; 0.01). Additionally, the 99th, and 99.5th percentiles of the survival group were significantly higher than those of the degenerative group in the 2nd period (P &lt; 0.05). The 95th, 99th, and 99.5th percentiles without UMR (n = 52) were significantly higher than those with UMR (n = 44) in the 1st period (P &lt; 0.001). Similarly, the 95th, 99th, and 99.5th percentiles without UMR were significantly higher than those with UMR in the 2nd period (P &lt; 0.001). ROC curves were generated at the 95th, 99th, and 99.5th percentiles in the 1st period. The resultant areas under the curve (AUC) were 0.73, 0.75, and 0.73, respectively. Using a threshold of 0.75 for the 99th percentile, oocyte degeneration was predicted with a sensitivity of 85% and specificity of 57%. In the 2nd period, ROC curves at the same percentiles resulted in the AUCs of 0.63, 0.69, and 0.67, respectively. Using a threshold of 0.69 for the 99th percentile, oocyte degeneration was predictable with sensitivity as 57% and specificity as 86%.

Limitations, reasons for caution
This study did not control for variations among the embryologists performing Piezo-ICSI. The culture outcomes and clinical outcomes had not been evaluated. We only showed the relationship between ooplasmic fluidity and oocyte degeneration because it was a retrospective study. A prospective study using image analysis is needed.

Wider implications of the findings
Before the investigation, we expected that more ooplasmic fluidity (less viscosity) could increase UMR and oocyte degeneration. This study, however, indicated that more ooplasmic fluidity (less viscosity) decreased UMR and oocyte degeneration. Elucidation of the mechanism under this phenomenon may lead to reduced UMR and oocyte degeneration.

Trial registration number
Not Applicable