研究開発・学会発表

Study question:

Are there different outcomes between the two different time-lapse embryo observation systems, EmbryoScope and PrimoVision?

 

Summary answer:

Although better outcomes are expected with PrimoVision, having a group culture system, no significant difference was detected in the time-lapse parameters and pregnancy rates.

 

What is known already:

Since time-lapse systems became available, some parameters, such as speed and timing of embryo development were reported to predict good embryos. Group culture systems have been reported to improve embryo development rates and pregnancy rates. Closed incubator systems are considered to produce similar results, as compared to conventional open incubator systems. Although there have been reports comparing closed and open systems, there was previously no reported data which compared the culture dishes used in each system.

 

Study design, size, duration:

Comparison of two different types of time-lapse system (EmbryoScope: a closed incubator with individual culture, PrimoVision: an open incubator with group culture). This was a retrospective cohort study involving 2,372 embryos from 270 women (<40 years old) who underwent blastocyst culture using the two time-lapse systems, and cryopreservation of their all blastocysts between September 2013 and October 2015. Patients were allocated randomly to each time-lapse system. Mouse embryo testing was performed on culture dishes.

 

Participants/materials, setting, methods:

The time from pronuclear membrane break down (PNMBD) to 2̴5 cells and 8 cells（tpnb2-tpnb5, tpnb8, from 2 to 3 cells (cc3), from 3 to 4 cells (s2), from 5 to 8 cells (s3) were compared between the two systems. Embryo development rates, pregnancy rates, and abnormal cleavage rates were compared between the two systems. The mouse embryo test was performed in ES and PV dishes in the same open system incubator.

 

Main results and the role of chance:

Blastocyst development rates in ES and PV were 57.7% (357/619) and 53.4% (339/633) and high quality blastocyst (≧G3BB) development rates in ES and PV were 26.5% (164/619) and 26.9% (170/633). Chemical and clinical pregnancy rates were 66.7% (58/87) and 60.9% (53/87) in ES and 61.4% (35/57) and 50.9% (29/57) in PV. Abnormal cleavage rates, including reverse cleavage and direct cleavage from 1 cell to more than 2 cells and from 2 cells to more than 4 cells were 9.2% (8/87) in ES and 8.8% (5/57) in PV. The parameters tpnb2, tpnb3, tpnb4, tpnb5, tpnb8, cc2, s2 and s3 were 2.4h±1.1, 13.0h±2.9, 14.1h±2.6, 26.3h±5.3, 33.9h±7.8, 10.6h±2.9, 1.1h±2.0, 7.6h±7.3 in ES, and 3.1h±5.3, 13.1h±7.2, 14.7h±7.1, 26.3h±8.9, 34.5h±9.6, 9.9h±3.7, 1.4h±2.4, 8.0h±7.1 in PV respectively. In all parameters, there was no significant difference between ES and PV. The mouse embryo test showed that the blastocyst development rate was significantly higher in PV dishes (78.1%) than in ES dishes (30.4%) (p=0.0011). No significant difference was detected between the ES dish culture (30.4%) and the control (individual) culture (36.4%), whereas the blastocyst rate was significantly higher in the PV dish culture (78.1%) than in the control (group) culture (31.3%) (p=0.00016).

 

Limitations, reasons for caution:

As only patients who are younger than 40 are enrolled in this time-lapse observation, the results may not be enhanced to assist patients who are older than 40.

 

Wider implications of the findings:

As there was no statistical difference between the two time-lapse systems, the merits in each system might counterbalance each other. A time-lapse system, which employs both a group culture system and a closed incubator system, using a less toxic culture dish, will improve ART outcomes.

 

Study funding/competing interest(s):

None

 

Trial registration number:

Not applicable