研究開発・学会発表
診療・治療
32nd Annual Meeting in Helsinki, ESHRE 2016
- Inner cell mass of blastocyst grade and loosening of inner cell mass is related to monochorionic diamniotic twinning
- 2016年7月3日(日)〜7月6日(水) ヘルシンキ
- 32nd Annual Meeting in Helsinki, ESHRE 2016
- Junko Otsuki, Toshiroh Iwasaki, Yuya Katada, Haruka Sato, Yukari Tsutsumi, Kanae Hatano, Yuta Tsuji, Kohyu Furuhashi, Yukiko Matsumoto, Shoji Kokeguchi and Masahide Shiotani
Hanabusa Women’s Clinic, Kobe, Japan
Study question:
Is inner cell mass (ICM) grade and morphological configuration is related to the occurrence of monochorionic diamniotic (M-D) twinning?
Summary answer:
Yes, low ICM grade and loosening of ICM can be the risk factors of M-D twinning.
What is known already:
Monozygotic twinning (MZT), which includes monochorionic diamniotic (M-D), monochorionic monoamniotic (M-M) and monozygotic dichorionic diamniotic (D-D) is known to increase with ART procedures. Extended culture, younger age, oocyte/embryo manipulations such as assisted hatching (AH) and ICSI have been considered to contribute MZT, however, they are still controversial and it remains unknown what factors contribute to that increased risk.
Study design, size, duration:
Retrospective cohort study involving 8435 women who underwent frozen-thawed single blastocyst transfer with hormone replacement treatment (HRT) between January 2011 and December 2014. 71 ICM of blastocysts observed by time lapse system (Embryo Scope) from June 2013 to December 2014 were also retrospectively analyzed.
Participants/materials, setting, methods:
Statistical analyses were carried out to explore the cause of MZT. Any changes in configuration of the ICM observed by time lapse system was retrospectively analyzed. Loosening of the ICM was defined as when more than 5 cells were loosened after a tight ICM was once observed by the time lapse system. Pregnant patients underwent a vaginal ultrasound and monozygotic twinning (M-D, M-M and D-D) was confirmed at both 6-7 weeks and 8-9 weeks.
Main results and the role of chance:
A total of 8435 frozen-thawed single blastocyst transfer with HRT resulted in 3445(40.8%) clinical pregnancies having a total of 80 MZT (2.32%). The number of M-D, M-M D-D twins and monochorionic triplet were 36(1.04%), 3(0.09%), 39(1.13%) and 2(0.06%) respectively. Gender discordance in twins was found in two D-D cases. The rate of dual live birth was also significantly higher in M-D twinning than in D-D twinning (p=0.0017). The M-D twinning rate when blastocysts with a high grade ICM (grade A) were transferred was 0.38%(3/796), whereas it was 1.38%(34/2463) when blastocysts with a lower grade ICM (grade B and C) were transferred, and there was a significant difference between the two groups (p=0.033). 71 frozen-thawed blastocysts were transferred after observation by time-lapse system. The hCG, GC, FHB positive rates were 74.2%(52/71), 63.4%(45/71), 57.7%(41/71) respectively, and there were two D-D and one M-D twins. Among the 41 cycles with positive FHB, 36 cases were delivered, 4 cases miscarried and 1 case lost contact. By careful observation of the embryo resulting in the one M-D case, it was found that the ICM became loose as a result of having 8 cells de-compacted, which was not observed in the other ICM of transferred blastocysts.
Limitations, reasons for caution:
The birth of babies derived from natural conception cannot be eliminated although the occurrence is very small. As the occurrence of M-D twinning is around 1% and availability of data and time-lapse systems are limited, multi-center study is necessary to confirm these findings.
Wider implications of the findings:
The occurrence of M-D twinning can be reduced by avoiding the transfer of embryos when the loosening of ICM is confirmed by time-lapse observation in addition to observing splitting of two or three inner cell masses in an expanded blastocyst.
Study funding/competing interest(s):
None
Trial registration number:
Not applicable
