An innovative design for trophectoderm biopsy without laser pulses: A step-by-step demonstration.

OBJECTIVE: To present a novel trophectoderm biopsy method independent of laser pulses using innovatively designed micropipettes on blastocysts at different stages and showing variable characteristics.

DESIGN: A step-by-step demonstration of this method with narrated video footage.

SETTING: In vitro fertilization laboratory.

PATIENTS: Individuals whose embryos underwent preimplantation genetic testing.

INTERVENTIONS: Trophectoderm biopsy is accomplished using micropipettes that contain a set of innovative designs. The biopsy and holding pipettes are both characterized by sharp, flat opening ends. The holding pipette is designed with an inclined plane on the outer wall surface of its opening end; this aims to help the biopsy pipette make contact with the holding pipette with increased stability, preventing slipping during the detachment of the trophectoderm cells. There is a narrow structure inside the biopsy pipette designed to trap released fragments and prevent sample loss. A trophectoderm biopsy for fully expanded blastocysts commences from artificial shrinkage, followed by zona pellucida drilling. Then, 5-10 trophectoderm cells are aspirated into a biopsy pipette. The blastocyst is released from the holding pipette, the edge of the opening end of the biopsy pipette is tightly pressed onto the inclined plane of the holding pipette, and the biopsy pipette is directly flicked without laser pulses or pulling of the trophectoderm cells. The aspirated trophectoderm cells are subsequently detached by the mechanical friction between the edges of the biopsy and holding pipettes. Other than drilling the zona pellucida for fully expanded blastocysts, the remaining steps do not require lasers. For hatching (including peanut-shaped and 8-shaped) and hatched blastocysts, a trophectoderm biopsy is accomplished by aspirating the cells without securing the blastocyst with a holding pipette, followed by detachment using the direct flicking method.

MAIN OUTCOME MEASURES: The biopsy time, the sample loss rate, the successful DNA amplification rate, and the survival rate.

RESULTS: The innovatively designed micropipettes facilitate the successful detachment of trophectoderm cells through a single direct flicking procedure. This eliminates thermal damage caused by laser pulses, notably simplifying operational steps and shortening the biopsy time. Significant differences were noted between the direct flicking method and the conventional method, in which laser pulses and pulling of trophectoderm cells are prerequisites for cell detachment. When comparing the average biopsy time of fully expanded blastocyst (61 ± 8 s vs 104 ± 9 s, p<0.05), peanut-shaped hatching blastocyst (35 ± 6 s vs 113 ± 13 s, p<0.05), 8-shaped hatching blastocyst (32 ± 4 s vs 59 ± 6 s, p<0.05), and hatched blastocyst (34 ± 4 s vs 67 ± 8 s, p<0.05), the direct flicking method shows a significantly decreased biopsy time. The narrow structure inside the biopsy pipette effectively prevents sample loss, showing a significantly reduced sample loss rate (0%) compared to the conventional biopsy method (18%) for trainees. Moreover, a satisfactory survival rate (100%) and successful DNA amplification rate (99.5%) were achieved using the direct flicking method.

CONCLUSIONS: This innovative trophectoderm biopsy method independent of laser pulses has wide applicability and a satisfactory, stable performance. Moreover, the simplicity of the method makes it easy to master.