Optimization of a dilution method for human expanded blastocysts vitrified using EM grids after artificial shrinkage.
OBJECTIVE
To verify a more effective dilution method that can be applied to human expanded blastocysts that are vitrified after artificial shrinkage.


METHODS
Surplus expanded blastocysts that remained after embryo transfer (ET) in in vitro fertilization (IVF) cycles, were cryopreserved. The blastocysts were vitrified on EM grids following artificial shrinkage. After thawing the blastocysts, cryoprotectants were diluted using either a 6- or 2-step method. We examined the survival rate and clinical outcome of blastocysts of 151 patients in our ET program after thawing.


RESULTS
The survival rate of blastocysts that were thawed using a 2-step method (91.6%, 239/261) was comparable with that of the 6-step method (89%, 186/209). The clinical pregnancy rate (45.9%, 39/85) and implantation rate (24.1%, 53/220) were slightly higher in the 2-step method than in the 6-step method (40.9%, 27/66; 19.4%, 33/170).


CONCLUSIONS
Our data indicate that the 2-step dilution method could be a simpler and more effective protocol for human expanded blastocysts that are vitrified using EM-grid following artificial shrinkage.
In Vitro Fertilization Laboratory, Maria Infertility Hospital, Dongdaemun-gu, Seoul, South Korea. snail0@mariababy.com
So-Young
SY
Lee
Hyung-Jun
HJ
Kim
Sung-Jin
SJ
Park
Hye-Jin
HJ
Yoon
San-Hyun
SH
Yoon
Kyung-Hoon
KH
Lee
Won-Don
WD
Lee
Jin-Ho
JH
Lim
D001755:Blastocyst; D015925:Cryopreservation; D046149:Embryo Culture Techniques / Q000379:methods*; D006801:Humans; D008854:Microscopy, Electron / Q000295:instrumentation