Does laboratory practice need to change?

Does laboratory practice
need to change?
One Child at a Time
“Clinical embryologists need
to develop embryo rating and
cryopreservation policies with
a focus on increasing the
proportion of cases in which
eSET is performed.”
The 3 key points
• Embryo Selection
• Day of embryo transfer
• Cryopreservation strategies
Professional Guidelines
• To provide a review of literature
• To provide an evidence base
• To make recommendations
BUT they are not meant to be prescriptive
Labs will develop their own policies based on
their clinical practice and patient population
A starting point
Embryo Selection
Evidence suggests that
embryo ‘quality’ is the most
predictive factor
for outcome of treatment,
with a correlation existing
between
early embryo morphology
and implantation rate
Recommendations
• Evidence based national grading scheme
• Wide variation between labs and individuals
(ACE pilot scheme)
• Consistency and reproducibility
• Used within a national EQA scheme developed
by NEQAS
Suggested Grading Scheme
Early Cleavage
Blastocyst
Blastomere number
Blastomere size
4 = regular, even division
3 = <20% difference (blast diam)
2 = 20-50% difference
1 = >50% difference
Hardarson et al 2001
Fragmentation
4 = <10% frags by volume
3 = 10-20%
2 = 20-50%
1 = >50%
van Royen et al 200335
Example: The grade is recorded as [cell number] c (size/fragmentation); therefore a 4cell embryo with slightly uneven cell division (~10% difference in cell size) and around
30% fragmentation by volume will be scored as 4c(3/2)
Embryo grading
2-cell
4-cell
8-cell
2-cell
4-cell
Grade 4
Grade 3
Grade 2
Grade 1
BLASTOMERE SIZE
FRAGMENTATION
8-cell
Embryo morphology
4c (3/4)
8c (4/4)
4c (1/3)
4c (4/4)
8c (3/4)
2c (3/3)
4c (1/1)
1c (-/1)
Blastocyst scheme
• Based on scheme originally developed by
Gardner and Schoolcraft and developed
further by Stephenson et al.
• Three-part system, already utilised by
many centres worldwide, appears to be a
more accurate predictor of clinical
outcome than other less detailed systems
of grading.
Expansion Status
1=
Early blastocyst; blastocoel less than half the volume of the embryo,
little or no expansion in overall size, zona pellucida (ZP) still thick
2=
Blastocyst; blastocoel more than half the volume of the embryo, some
expansion in overall size, ZP beginning to thin
3=
Full blastocyst; blastcoel completely fills the embryo.
4=
Expanded blastocyst: blastocoel volume now larger than that of the
early embryo. ZP very thin
5=
Hatching blastocyst; trophectoderm has started to herniated through
the ZP
6=
Hatched blastocyst; the blastocyst has evacuated the ZP
ICM grading
A=
ICM prominent, easily discernible and consisting of many cells, cells
compacted and tightly adhered together
B=
Cells less compacted so larger in size, cells loosely adhered together,
some individual cells may be visible
C=
Very few cells visible, either compacted or loose, may be difficult to
completely distinguish from trophectoderm
D=
Cells of the ICM appear degenerate or necrotic
E=
No ICM cells discernible in any focal plane
Trophectoderm
a=
Many small identical cells forming a continuous trophectoderm layer
b=
Fewer, larger cells, may not form a completely continuous layer
c=
Sparse cells, may be very large, very flat or appear degenerate
Blastocyst Grading
Blastocyst grading - I
Grade 4
Grade 3
Grade 5
Grade 2
Grade 6
Grade 1
EXPANSION STATUS
Blastocyst grading - II
ICM
TROPHECTODERM
Grade
A
Grade B
Grade a
Grade E
Grade b
Grade C
Grade D
Grade c
Blastocyst Morphology - good☺
2Aa
5Aa
4Aa
6Aa
Blastocyst Morphology - bad
3Ea
3Ba
5Ba
Day of Embryo transfer
• Different strategies
– Scandinavian countries: early cleavage
– Australia: Blastocyst
• Day of ET influenced not only by biological
criteria but also workforce planning and
resources
Evidence – blastocyst transfer
• Higher pregnancy and live birth rates for
selected patient populations
• Recent systematic review and metaanalysis demonstrated a much improved
live birth rate compared to the early
cleavage stage when equal numbers of
embryos were replaced
Cryopreservation
Many studies have shown pregnancy rates
were significantly lower for patients having
eSET for individual fresh and frozen cycles
NEED EFFECTIVE
CRYOPRESERVATION
BUT
PROGRAMMES
the cumulative live birth rates between
the DET and eSET groups were not
significantly different.
Evidence
• The most important determinant of postthaw quality is the percentage of
blastomeres remaining intact, embryos
with no apparent cell loss appear to do
best
• Recent developments using vitrification
appear to result in significantly improved
survival rates
Developing a lab strategy
• Suggested basic algorithm of
management
• Develop own strategy based on
– Own data
– Experience
– Patient population
– Workforce
– Resources
Patients <37 years, 1st cycle
(all donor egg patients)
Day
2
3
5
I top grade
embryo
2-3 top grade embryos
SET
Culture to day 3
4+ Top grade embryos
Culture to day 3
1-3 top grade
embryos
0 top grade
embryos
1-3 top grade
embryos
Eset day 3
and cryo
DET day 3
eset day 3
and cryo
4+ top grade
embryos
eset day 3 and cryo OR
Culture to day 5
0 good blastocysts
1+good blastocyst
2 BT if available
eSBT and cryo
Conclusion
Develop our own strategies based on:
EMBRYO SELECTION
AUDIT THE
EFFECT ON MBR
DAY OF EMBRYO
TRANSFER
And importantly……….
!
CRYOPRESERVATION
Acknowledgments
Novocellus Project
ACE/BFS guidelines
Diane Critchlow
Tony Rutherford
Daniel Brison
Steve Roberts
Catherine Wass
Susan Pickering
Ruth Arnesen
David Morroll
Rachel Cutting