IDENTIFICATION OF THE OPTIMAL PUNCTURE POSITION BY A REAL-TIME IMAGE ANALYSIS CAN REDUCE OOCYTE DEGENERATION IN PIEZO-ICSI

Abstract

It is known that the oocyte degeneration after ICSI is often observed when unintentional membrane rupture (UMR) occurs during the puncturing process. In case of Piezo-ICSI, UMR is defined as an unpredictable rupture of membrane prior to the application of Piezo pulses. We have reported that visualization of the shape features of the oocyte membrane (oolemma) using moving image analysis during Piezo-ICSI can locate areas on the oolemma where UMR is likely to occur. Based on this principle and accumulating imaging data, we have developed an imaging system called ICSI POSITION DETECTOR (IPD), which can identify an area where rupture is likely to occur and visualize it in real-time on a video monitor. In this study, we assessed whether IPD is clinically useful for reducing oocyte degeneration. This study included a total of 662 Piezo-ICSI inseminated oocytes from 71 consenting patients (77 treatment cycles, average maternal age: 38.5±4.6 y.o.) and moving images were recorded during Piezo-ICSI using IPD. In order to evaluate the usefulness of IPD, Piezo-ICSI was performed blindly, while images by IPD were recorded and analyzed retrospectively. Inseminated oocytes were subsequently divided into two groups according to IPD results, 522 oocytes in which ICSI was performed at a position that IPD identified as having a low chance of UMR (IPD recommended group) while 140 oocytes at a position with a high chance of UMR (IPD not-recommended group). The rates of UMR, degeneration, fertilization, blastocyst formation, and good-quality blastocyst (Grade 3BB and above on day 5 by the Gardner scoring) were compared between the two groups. A chi-square test was used for statistical analysis. The areas in which UMR is less likely to occur and the one more likely to occur are heterogeneously distributed. When Piezo-ICSI was performed blindly, 21.1% of oocytes (140 out of 662) happened to be punctured at an unfavorable position. The rate of UMR in IPD recommended group was 6.9%, significantly lower than IPD not-recommended group (18.6%, P<0.001). Similarly, the rate of oocyte degeneration in IPD recommended group was 1.3%, remarkably lower than the counterpart (5.0%, P<0.05). The rates of fertilization (85.8% vs. 79.3%), blastocyst formation (52.9% vs. 48.6%), good-quality blastocyst (24.8% vs. 22.8%) were all in favor of IPD recommended group, but not significanly different. The IPD recommended group showed lower rates of UMR and degeneration than the IPD not-recommended group. These results indicate that real-time visualization of the shape feature of the oolemma using IPD is capable of reducing oocyte degeneration by 75%, and consequently generating more fertilized oocytes and embryos available for transfer or cryopreservation. It warrants a further prospective study.