Quantitative evaluation of intercellular local deformation of human oocytes during Piezo-assisted intracytoplasmic sperm injection using video-based motion analysis.

Objective: To evaluate the relationship between the quantitative properties of local deformation of the ooplasm during Piezo-assisted intracytoplasmic sperm injection (Piezo-ICSI) and oocyte developmental fate after Piezo-ICSI.

Design: Video-based motion analysis and case-control study.

Setting: Private fertility center.

Patient(s): A total of 99 couples assigned to the standard Piezo-ICSI program.

Intervention(s): Video recordings of the sperm injection process during Piezo-ICSI.

Main Outcome Measure(s): Quantitative deformation properties consisting of the orientation of deformation perpendicular (Perp) or parallel (Para) to the oolemma and the mechanical response of the ooplasm (elongation, contraction, and total): Perp, Perp, Perp, Para, Perp, and Para.

Result(s): The deformation parameters were compared among different angular ranges of 30°-60°, 60°-90°, 90°-120°, and 120°-150° (defined as 0° at the 3 o'clock puncture site). The Perp value at 30°-60° was significantly greater than that at the other angles (130.2 vs. 57.7-85.5, respectively) primarily due to substantially greater Perp values. The Para value at 30°-60° was significantly greater than that at the other angles (20.1 vs. 6.7-10.3, respectively) primarily due to substantially smaller Para values. The deformation parameters of the ooplasm adjacent to the first polar body were also compared among different developmental fates (fertilization failure, cleavage arrest, and blastocyst development). The Perp value of oocytes derived from blastocyst formation was significantly smaller than those derived from other developmental fates (58.1 vs. 70.0-87.3, respectively).

Conclusion(s): The Piezo-ICSI process induced deformation with various mechanical behaviors in different regions within a single oocyte. Furthermore, the exposure of the ooplasm adjacent to the first polar body to excessive deformation was found to be a possible trigger for adverse fertilization and embryo development after Piezo-ICSI.