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Developmental potential of surplus morulas with delayed and/or incomplete compaction after freezing-thawing procedures.
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ABSTRACT: Background
Morulas with delayed growth sometimes coexist with blastocysts. There is still limited evidence regarding the optimal disposal of surplus morulas. With the advancement of vitrification, the freezing-thawing technique has been widely applied to zygotes with 2 pronuclei, as well as embryos at the cleavage and blastocyst stages. The freezing of morulas, however, has rarely been discussed. The purpose of this study was to investigate whether these poor-quality and slow-growing morulas are worthy of cryopreservation.Methods
This is a retrospective, observational, proof-of-concept study. A total of 1033?day 5/6 surplus morulas were cryopreserved from January 2015 to December 2018. The study included 167 women undergoing 180 frozen embryo transfer cycles. After the morulas underwent freezing-thawing procedures, their development was monitored for an additional day. The primary outcome was the blastocyst formation rate. Secondary outcomes were clinical pregnancy rate, live birth rate and abortion rate.Results
A total of 347 surplus morulas were thawed. All studied morulas showed delayed compaction (day 5, n?=?329; day 6, n?=?18) and were graded as having low (M1, n?=?54), medium (M2, n?=?138) or high (M3, n?=?155) fragmentation. The post-thaw survival rate was 79.3%. After 1 day in extended culture, the blastocyst formation rate was 66.6%, and the top-quality blastocyst formation rate was 23.6%. The day 5 morulas graded as M1, M2, and M3 had blastocyst formation rates of 88.9, 74.0, and 52.8% (p?ConclusionsThe post-thaw blastocyst formation rate was satisfactory, with approximately one-half of heavily fragmented morulas (M3) developing into blastocysts. Most of the poor-quality morulas were worth to freeze, with the reasonable goal of obtaining pregnancy and live birth. This alternative strategy may be a feasible approach for coping with poor-quality surplus morulas in non-PGS (preimplantation genetic screening) cycles.
SUBMITTER: Tsai NC
PROVIDER: S-EPMC6821030 | biostudies-literature | 2019 Oct
REPOSITORIES: biostudies-literature
Publications
Developmental potential of surplus morulas with delayed and/or incomplete compaction after freezing-thawing procedures.
Reproductive biology and endocrinology : RB&E 20191030 1
<h4>Background</h4>Morulas with delayed growth sometimes coexist with blastocysts. There is still limited evidence regarding the optimal disposal of surplus morulas. With the advancement of vitrification, the freezing-thawing technique has been widely applied to zygotes with 2 pronuclei, as well as embryos at the cleavage and blastocyst stages. The freezing of morulas, however, has rarely been discussed. The purpose of this study was to investigate whether these poor-quality and slow-growing mor ...[more]