P–134 Zygote morphokinetic parameters (ZMP) differs between fertilized and non-fertilized (in vitro maturation) oocytes

Abstract

Abstract Study question Is there any difference on the ZMP between the fertilized and the non-fertilized oocytes in an IVM cohort? Summary answer The zona pellucida (zp_g) , cytoplasm greyscale（cm_g),the cytoplasm size (cm_size), radius (cm_r) and deviation (cm_d) showed different patterns from the two groups. What is known already We developed a convolutional neural network (CNN) based algorithm that provides instant and bias-free analytical outcomes of oocyte morphological segmentation. The mature but not-fertilized oocytes tend to be static while the fertilized oocytes are more dynamic for preparing its following biological events. Study design, size, duration This was a case-control study on oocytes including 631 normal fertilized oocytes and 100 IVM oocytes from 01/08/2017 to 31/12/2019 conducted in the Prince of Wales Hospital, The Chinese University of Hong Kong. Participants/materials, setting, methods We used the convolutional neural network (CNN) algorithm to segment the ZMPs of the cytoplasm and zona pellucida of the oocytes. The ZMPs include cm_g, cm_size, cm_r, cm_d, zp_g, thickness of zona pellucida and the area of perivitelline space. For the ZMPs that did not change with time, we used t-test to test the significance and for the parameters changed with time we used dynamic warp timing and similarity test to find the difference. Main results and the role of chance The IVM group had a higher intensity of zp_g of 142.03 (128.52–158.70) compared with the fertilized group of 137.04 (121.69–154.37). The cm_g of IVM group was higher than fertilized group [122.55 (114.87–137.62) vs 119.37(108.88–132.87)]. The cm_size, cm_r and cm_d as parameters changed with time and showed a different pattern in two groups. The IVM group decreased the cm_size faster than the fertilized group but the fertilized group had a more dynamic change in the shape of cytoplasm (cm_d) during the development. The cm_r changed with the same pattern of cm_size provided evidence supporting the finding above. Limitations, reasons for caution The ZMPs in the IVM group was captured for 21 hours from the first polar body extrusion. Though the duration was similar to the one from fertilized to the first cleavage. The morphology change during that period may not represent the holistic one of IVM oocytes. Wider implications of the findings: The IVM oocytes have different morphokinetic performance from fertilized oocytes. We used a novel method based on CNN to confirm the differences between the two groups showing that our algorithm was able to describe the morphokinetic changes in a quantitative way and corresponded with embryologist’s experience. Trial registration number The Hong Kong Obstetrical & Gynaecological Trust Fund