Time-lapse imaging of inner cell mass splitting with monochorionic triamniotic triplets after elective single embryo transfer: a case report.

RESEARCH QUESTION: Can detailed scrutiny of time-lapse imaging (TLI) of inner cell mass (ICM) splitting help to reduce the frequency of multiple pregnancies following elective single embryo transfer (eSET)?

DESIGN: Retrospective analysis of time-lapse images of an embryo in vitro, which resulted in a monochorionic triamniotic pregnancy following eSET on Day 5 of development.

RESULTS: A 37-year-old female patient underwent a frozen embryo transfer cycle whereby a single vitrified/warmed embryo was transferred at the hatching blastocyst stage. The subsequent pregnancy scan revealed a monochorionic triamniotic pregnancy. Because the blastocyst was cultured in an incubator incorporating TLI, retrospective scrutiny of the digital recordings demonstrated two distinct ICM structures splitting apart, which formed during the '8-shaped hatching'.

CONCLUSIONS: Assisted reproductive techniques and in-vitro culture have been associated with an increased frequency of embryo splitting. This has been postulated to be linked to the in-vitro hatching method observed at the blastocyst stage of development. This case report highlights the need to objectively assess any splitting of the ICM, beyond standard grading of the quality of the ICM and the trophectoderm. Such assessments of ICM splitting should be routine practice in clinical embryology when selecting embryos for transfer.