An effective method for trophectoderm biopsy using mechanical blunt dissection: a step-by-step demonstration
A series of systematic and effective biopsy strategies based on mechanical blunt dissection is demonstrated for blastocysts of different stages and characteristics.
VOLUME 114, ISSUE 2, P438-439
Dalei Yang, M.S., Di Feng, M.D., Yingzhuo Gao, M.S., Matthew Sagnelli, B.S., Xiuxia Wang, M.D., Ph.D., Da Li, M.D., Ph.D.
To present an effective approach to trophectoderm biopsy for blastocysts of different stages and characteristics by mechanical blunt dissection (MBD).
Stepwise demonstration with still pictures and operational video clips to explain tips and tricks for trophectoderm biopsy. (This demonstration was approved by the Reproductive Study Ethics Committee at Shengjing Hospital of China Medical University.)
In vitro fertilization laboratory.
Patients who underwent preimplantation genetic testing.
The illustrated techniques of blastocyst trophectoderm biopsy using micromanipulation methods include artificial shrinkage, zona pellucida drilling, injecting media from the drilling, aspiration of trophectoderm cells into the biopsy pipette (outer diameter 27 μm for fully expanded blastocysts and peanut-shaped hatching blastocysts; outer diameter 20 μm for 8-shaped hatching and hatched blastocysts), detachment of the trophectoderm cells by laser pulse combined with MBD (performed using the rims of the biopsy and holding pipettes), and release of the biopsy fragment.
Main Outcome Measure(s)
Successful biopsy rate and survival after warming.
Our biopsy strategy does not involve assisted hatching on day-3 or day-4 embryos, which can leave the embryo undisturbed in culture up to the expanded blastocyst stage. Notably, this approach demonstrates several noteworthy advantages for sampling blastocysts of different stages and characteristics, and it maintains a desirable successful biopsy rate (95.4%, n = 1,872) and survival rate after warming (100%, n = 440). The MBD method may reduce thermal damage because fewer laser pulses are used, compared with the traditional laser-only biopsy techniques. For noncollapsed blastocysts after artificial shrinkage, the strategy of injecting medium from the zona pellucida drilling helps to separate the trophectoderm cells from the zona pellucida, thus facilitating the biopsy procedure. For peanut-shaped hatching blastocysts, this approach could provide better control over the aspiration of trophectoderm cells into the biopsy pipette. Especially if the inner cell mass is herniating from the zona pellucida, the trophectoderm biopsy can be performed away from the inner cell mass to avoid damaging it. In addition, the MBD approach combined with the biopsy pipette (outer diameter 20 μm) can effectively control the target number of trophectoderm cells, thus simplifying the process of obtaining a biopsy from a hatched blastocyst.
Our biopsy approach demonstrates several noteworthy advantages. Considering its benefits and the simplicity of its execution, this systematic biopsy method for blastocysts of different stages and characteristic can be widely applied.