The value of fast blastocoele re-expansion in the selection of a viable thawed blastocyst for transfer

Fertil Steril. 2009 Feb;91(2):401-6. doi: 10.1016/j.fertnstert.2007.11.083. Epub 2008 Mar 4.


Objective: To investigate the role of fast blastocoele re-expansion in the selection of viable thawed blastocysts for transfer.

Design: Retrospective study.

Setting: Academic assisted reproductive program.

Patient(s): Transfer cycles were divided into two groups according to the presence or absence of fast re-expanded blastocysts. In group I (124 cycles), all transferred blastocysts had fast re-expanding blastocoele. In group II (113 cycles), no fast re-expanded blastocysts were included in the transfer.

Intervention(s): Blastocyst survival was defined as >50% of cells remaining intact after thaw and re-expansion after culture in vitro for 2-4 hours before transfer. Blastocysts with >or=50% re-expansion were designated as fast re-expanded blastocysts.

Main outcome measure(s): Percentage of blastomere loss immediately after thaw, degree of blastocoele re-expansion, and clinical outcomes (pregnancy and implantation rates).

Result(s): The rates of survival and fast blastocoele re-expansion of partially intact blastocysts were significantly reduced as compared with fully intact blastocysts. Significantly higher rates of clinical pregnancy (37.1% vs. 16.8%) and implantation (26.7% vs. 11.3%) were obtained when all transferred blastocysts had fast re-expanding blastocoele as compared with those transfers without fast re-expanded blastocysts included.

Conclusion(s): Our results showed that blastomere loss of thawed blastocyst was associated with a reduced ability to re-expand. As a discriminative morphologic marker of superior embryo viability, a fast re-expanded blastocyst would be given priority for transfer to better utilize the cryopreserved blastocysts.

MeSH terms

  • Adult
  • Blastocyst*
  • Cell Proliferation*
  • Cell Survival
  • Cryopreservation*
  • Embryo Culture Techniques
  • Embryo Implantation
  • Embryo Transfer*
  • Female
  • Humans
  • Pregnancy
  • Pregnancy Rate
  • Retrospective Studies
  • Time Factors
  • Treatment Outcome