O-204 Is mosaicism affected by an embryologist’s experience in biopsy?
Authors: Yap W Y , Lim M W , Lee C S S 
Published: August 2021

Abstract

Study question
Are there any correlations between blastocyst mosaicism rate and biopsy experience among embryologists?

Summary answer
Blastocysts biopsied by embryologists with ≥1 year of biopsy experience have significantly lower mosaicism rate compared to those with &lt;1 year of biopsy experience.

What is known already
It has been reported that the incidence of blastocyst mosaicism is highly variable between centres (PGDIS, 2019). It is also suggested that the technical aptitude of the embryologist performing blastocyst biopsy may give rise to mosaicism. Thus, a retrospective study was conducted to investigate the relationship between blastocyst mosaicism rate and biopsy experience among embryologists in Alpha IVF.

Study design, size, duration
Thirteen competent embryologists who were trained in blastocyst biopsy were included in this study: 5 have ≥1 year of biopsy experience (Group A; Embryologist A-1, A-2, A-3, A-4, A-5); 8 have &lt;1 year of biopsy experience (Group B; Embryologist B-1, B-2, B-3, B-4, B-5, B-6, B-7, B-8). Embryologists from Group A biopsied a total of 4795 blastocysts while those from Group B biopsied 4869 blastocysts from January 2018 to December 2019.

Participants/materials, setting, methods
TE biopsy was performed either on Day 5, 6 or 7 using the laser or flicking method. The biopsied cells had Preimplantation Genetic Testing for Aneuploidy (PGT-A) analysed using Next Generation Sequencing (Ion Torrent, USA) and chromosomal mosaicism analysis was done using ReproSeq Mosaic PGS w1.1 workflow. Mosaic blastocysts were reported when 20% - 80% of aneuploid cells are tested in the biopsied samples. Only successfully amplified biopsy samples were included in this study.

Main results and the role of chance
The mosaicism rate of blastocysts biopsied by embryologists from Group A and B were 17.8% and 19.8% respectively. Blastocysts from Group A showed significantly lower mosaicism rate compared to Group B (p = 0.01). The mosaicism rates of blastocyst biopsied by Embryologist A-1, A-2, A-3, A-4 and A-5 were 17.3%, 19.1%, 16.8%, 15.2%, and 18.9% respectively. The mosaicism rates of blastocyst biopsied by Embryologist B-1, B-2, B-3, B-4, B-5, B-6, B-7, and B-8 were 17.5%, 18.6%, 22.5%, 20.4%, 27.8%, 20.6%, 20.1% and 20.3% respectively. There were no significant differences in blastocyst mosaicism rate between embryologists within Group A (p &gt; 0.05). Contrarily, in Group B, Embryologist B-5 had a significantly higher blastocyst mosaicism rate compared to the other embryologists within the same group (p &lt; 0.05).

Limitations, reasons for caution
Since this study is retrospective in nature, the biopsy technique (either the laser or flicking method) was not controlled. Hence, further studies to analyse the differences between these 2 biopsy techniques should be carried out to confirm its effect on the occurrence of blastocyst mosaicism.

Wider implications of the findings
Our study demonstrates that blastocysts biopsied by embryologists with ≥1 year of biopsy experience have significantly lower mosaicism rate compared to those with &lt;1 year of biopsy experience. This indicates that the skill and experience of an embryologist in biopsy may have an impact on the mosaicism rate.

Trial registration number
Not applicable