Embryo Biopsy Flashcards
Identify 3 primary stages of embryo biopsy
How to breach the ZP in embryo biopsy?
Pros/cons of each approach?
No difference in laser vs acid in terms of embryo outcome, though some have noted higher rate of cell lysis with acid.
Overall, 98.8% successful biopsies in US SART data.
Laser - quick & easy, but exposes embryo to heat and is $$$
Acid - cheap, but requires a dual pipette setup, may expose blastomeres to acid, requires extensive training
What does the amount of heat seen by the embryo depend on during laser biopsy?
Pulse duration (longer duration = bigger hole)
Distance from laser
Power (set by manufacturer)
What is the problem with performing embryo biopsy on only 1 polar body on D1?
Premature separation of sister chromatids can allow for aneuploid polar bodies but euploid embryos. If the wrong polar body is biopsied, can lead to discard of potentially viable embryos
(theoretically, if both PBs are euploid, oocyte is euploid)
Pros/Cons of polar body biopsy
Pros - every potential embryo can be biopsied, biopsy of non-embryonic material (will not affect subsequent embryo development), results available within 5-6 days, allowing for fresh ET
Cons - no info re: paternal DNA contribution (though majority of aneuploidy is maternally derived) , only meiotic errors noted, 2-day biopsy (biopsy PB #1 on day 0 prior to ICSI, then #2 on day 1 vs both on day 1).
How many blastomeres are typically removed at cleavage biopsy stage?
1 (sometimes 2)
Pros/cons of cleavage stage biopsy
Pros - potential to biopsy every embryo, info re: both maternal and paternal, allows 2-3 days for genetic material
Cons - damage to embryo, requires exposure to Ca/Mg-free medium to loosen junctions between blastomeres, mosaicism
Important considerations for cleavage-stage biopsy technique
Blastomere to be biopsied should be positioned at 3:00
Use of Ca/Mg-free medium to loosen junctions
Care not to lyse blastomere during removal (avoid aspiration into pipette)
3 methods:
- Aspiration technique
- Displacement method
- Extrusion method
Where should polar body be aligned during biopsy?
12:00
Pros/Cons of 1 vs 2 cell removal in cleavage stage biopsy
1-cell: less detrimental? (no diff in LBR), but less time in Ca2+/Mg2+ free medium
2-cell: detect mosaicism, diagnosis of single gene (allele dropout ADO)
Blastocyst biopsy pros/cons
Pros - does not decrease implantation, CCS limits effects of mosaicism (single result for 5-6 cells)
Cons - does not allow for biopsy of every embryo, does not allow for a fresh transfer, euploid blastocyst must survive the thaw after
Pros/cons of assisted hatching on D3 for blastocyst biopsy
Assisted hatching to assist protrusion of trophectoderm from ZP and allow for an easier biopsy
However, AH on D3 may cause premature hatching, which may lead to biopsy of non-expanded embryos and affect embryo development
ICM could end up hatching instead, requiring an additional trophectoderm hole
No AH allows for less intervention, allows for removal of trophectoderm directly (and furthest) across from ICM
However, it requires advanced training to minimize the number of laser pulses required to breach ZP and obtain trophectoderm biopsy
Cleavage vs blastocyst stage biopsy
Cleavage stage biopsied embryos appear to have lower implantation than blastocyst stage biopsied embryos
Where should trophectoderm be biopsied during blastocyst biopsy?
5:00, across from ICM
