The best timing of vitrification after blastocyst biopsy
7/14/2016 09:05:00 PM
What is the correlation between the vitrification timing
after biopsy and the following clinical outcomes?
Time is what we want most,
but we use worst.
Through preimplantation genetic screening (PGS), couples
with the indications of repeated implantation failure, recurrent miscarriage,
and advanced maternal age, may select the chromosomally normal embryo to
transfer (euploid embryo transfer). On the widely-used PGS platform—aCGH (now
has been gradually replaced by next-generation sequencing system), the tested
embryos must be vitrified after biopsy to wait for the PGS report release .
When should the embryologists vitrify the biopsied embryo? Does the timing of
vitrification correlate with the following clinical outcomes?
An information provided by Lee Women's Hospital in 2015 Annual Meeting of Taiwan Society of
Reproductive Medicine (2015 TSRM) displayed the clinical outcomes of different
vitrification timings after biopsy. A total of 224 cycles were involved, and
the biopsy criteria were shown as below:
1.
Gardner grading system: Grade of expansion 4, 5, 6
2.
Gardner grading system: Inner cell mass(ICM) and Trophectoderm(TE) Grade A
or B (AA/AB/BA/BB)
3.
Biopsy on Day 5 or Day 6
Table
1. The correlation between the timing of vitrification and embryo expansion before cyropreservation:
Table
2. The correlation between embryo expansion level at vitrification and
following clinical outcomes:
*The
survival rate of warming embryo =100%。
*The
single euploid embyro transfer was performed.
According
to Table 2, the implantation rate was higher in Group 4 than Group 1
(p=0.0492), and both the Group 3 and 4 had higher clinical pregnancy rates than
that of Group 1 (p=0.009 and p=0.027, respectively). Combining
the information in Table 1 and Table 2, vitrification after 3 hrs of biopsy
and with over 3/4 expansion displayed better clinical outcomes. Compared those
fitted these observations and those did not, both the implantation rate and
clinical pregnancy rate could reach significant difference (p=0.01 and p=0.006,
respectively).
The
above analyses was limited by its retrospective nature (e.g. sample size variation among groups), and it deserved further
study to validate the "best timing" of vitrification for the biopsied
embryos. More precise the timeline of embryo can be hold, better clinical
outcomes may be obtain.
Glad to learn something new, like reading your blogs, the same like learning something new about silica particles
ReplyDelete