RBA embryology grading system / My embryo grades

I asked for my embryology report from RBA and got it the other day. I was confused by it, asked some clarifying questions, and finally got this guide to help clarify:

rba embryo grading system

It seems quite different from the Gardner grading system. The embryology report for all three of my embryos has a column claiming that they are all “Grade A” embryos, but their inner cell mass (ICM) and trophectoderms are identified as “B.” If you were reading back in Sept  you might recall that Dr. S and the embryologist stated that the embryo that was transferred into me during my SET was an “A” and “perfect.” But I see on the embryology report something a little different.

Here’s how it breaks down:

  • Single embryo that was transferred in September: Day 5 “Grade A” XBBB embryo. X = Expanded. 1st B = Blastocyst. XB = Expanded Blastocyst, cells fill up more than 50% of the cavity. 2nd B = ICM (inner cell mass) is fair. 3rd B = Trophectoderm, there is a fair # and morphology of cells in the trophectoderm. Therefor, a BBB basically = fair size and cohesiveness.
  • Embryo that was frozen on transfer day: Day 5 “Grade A” EBBB embryo. E = Early. Cells fill up less than half of the cavity. The rest is the same as above.
  • Embryo that was frozen the day after transfer: Day 6 “Grade A” XBBB embryo. The same as the first one.

I’m fine with this—I know that “fair” embryos become successful pregnancies all the time. It’s just an odd grading system—why not just call them “Grade B” embryos instead of “Grade A”?

Thought I’d post this in case it is helpful to anyone trying to parse out their own grading system. An industry standard would be such an improvement.

Leave a comment


  1. so confusing!

  2. The printout makes sense. Calling an XBBB a “A” does not! So frustrating. Did they give you the printout? I’m taking it with me to Atlanta so they can’t look at me sideways when I say I want more than one letter!!!

  3. That’s very interesting! I’m totally fascinated by “data”. And I’ve seen other bloggers mention that their RE’s had been chastised for “upgrading” embryos. But it sounds like Dr. S is only slightly “fudging” the data by omitting some of it. XO sweets!

  4. Wow! I have heard about the two letter system but this is a lot! I always like more information. But you are smart to remember that the are just words. I am now pregnant with two embryos that were “good” and I have two frozen blasts that at first were scored “fair” and then matured to “good or excellent” a day later. It’s art and science I think

  5. Danielle

     /  December 24, 2013

    Thank you for sharing. I will definitely reference it when I go to Atlanta in January

  6. sarah go

     /  February 1, 2014

    I hope you won’t mind me asking but can i have a copy of your exact protocol/calendar? Interested to know more about ccrm protocol 3. I had 2 failed ivf’s and planning on a 3rd one. Thanks so much.

  7. My blast is the exact same grading as yours! XBBB! My beta is next Friday, I am praying that it will be BFP!!!!


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