CLEAVAGE VS BLASTOCYST STAGE EMBRYO TRANSFER

Transcription

1 CLEAVAGE VS BLASTOCYST STAGE EMBRYO TRANSFER

2 2013, Issue 6

3 Description of the Intervention Over the past decade there has been a steady shift in practice to transfer of embryos on Day 5 or 6 when the embryos are blastocysts, the 64-cell stage. The need for an evidence-based approach using meta-analysis of small trials was, therefore, required to assist in deciphering the overall effect of blastocyst culture to help identify patient subsets and practices that might best benefit from this approach.

4 ARGUMENTS FOR BLASTOCYST TRANSFER With the application of stage-specific media, there have been reports of blastocyst development and implantation rates as high as 60% to 65% (Shoolcraft 2001). The uterus provides a different nutritional environment from the oviduct; therefore it is postulated that this may cause stress on the embryo and result in reduced implantation potential (Gardner 1996). The second argument for blastocyst culture is their innately higher implantation potential compared with early cleavage embryos. As a consequence of self selection, it is postulated that only the most viable embryos are expected to develop into blastocysts.

5 Objectives To determine if blastocyst stage (Day 5 to 6) embryos transfers (Ets) improve live birth rate and other associated outcomes compared with cleavage stage (Day 2 to 3) Ets. Data Collection and analysis Of the 50 trials that were identified, 23 randomised controlled trials (RCTs) met the inclusion criteria and were reviewed (five new studies were added in this update). The primary outcome was rate of live birth. Secondary outcomes were rates per couple of clinical pregnancy, cumulative clinical pregnancy, multiple pregnancy, high order pregnancy, miscarriage, failure to transfer embryos and cryopreservation. Quality assessment, data extraction and meta-analysis were performed following Cochrane guidelines.

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9 Results There was no difference in clinical pregnancy rate between early cleavage and blastocyst transfer in the 23 RCTs and no difference in miscarriage rate (13 RCTs). Embryo freezing rates (11 RCTs, 1729 women) and failure to transfer embryos (16 RCTs, 2459 women) favoured cleavage stage transfer.

10 Authors conclusions This review provides evidence that there is a small significant difference in live birth rates in favour of blastocyst transfer (Day 5 to 6) compared to cleavage stage transfer (Day 2 to 3). However, cumulative clinical pregnancy rates from cleavage stage (derived from fresh and thaw cycles) resulted in higher clinical pregnancy rate than from blastocyst cycles. Future RCTs should report miscarriage, live birth and cumulative live birth rates to enable ART consumers and service providers to make well informed decisions on the best treatment option available.

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12 WHAT IS THE CHANCE OF A DAY 3 EMBRYO MAKING IT TO BLASTOCYST STAGE?

13 GOOD AND POOR AT CLEAVAGE STAGE

14 Overall Rates for Good or Poor Day 3 Embryos Making it to Blastocyst Good Day 3 Embryo 253/383 66% Poor Day 3 Embryo 300/872 34% P Value <.001 * Good defined as embryos having six to eight cells of equal size and less than 20% fragmentation ** Poor defined as not meeting above criteria

15 Implantation Rates for Good Blastocysts Derived from Good or Poor Day 3 Embryos Age of Eggs < Good Day 3 Embryo* 41/56 73% 10/15 67% Poor Day 3 Embryo** 43/109 39% 5/19 26% P Value < * Good defined as embryos having six to eight cells of equal size and less than 20% fragmentation ** Poor defined as not meeting above criteria Implantation rates are defined as # Sacs/ # Embryos Transferred

16 Pregnancy Rates for Good Blastocysts Derived From Good or Poor Day 3 Embryos Age of Eggs < Good Day 3 Embryo* 30/56 54% 9/15 60% Poor Day 3 Embryo** 37/109 34% 5/19 26% P Value * Good defined as embryos having six to eight cells of equal size and less than 20% fragmentation ** Poor defined as not meeting above criteria Pregnancy rates are defined as # Viable Pregnant/ # Transfer