Blastocyst grading
10 Replies
TS2005 - March 25

Dr. Smith,
Does at matter at which stage you transfer a blastocyst (in terms of success rate)? Can you explain blastocyst grading to me? It appears the the grading is based pretty much on the stage of development of the blastocyst.
I had 2pn frozen embryos (donor egg) cultured for 5 days and transferred a grade 2 blastocyst and a 3bb blastocyst. The embryologist told me they were early blasocysts but that it didn't matter if we transferred them then or after they had developed a little more. He said evaluating quality was a little difficult at the early stages but that they looked good.
Thank you for your input.


Dr Smith - March 27

For the most part, the embryologist was telling the truth. The grading system for blastocyst stage embryos is different from that used for early cleavage stage embryos. See

there were only two embryos that had reached the blastocyst stage, then I agree that there is no point in waiting any longer for the embryos to further develop to the expanded blastocyst stage. It wouldn't matter anyway. However, if there were additional embryos, it might have been prudent to wait until the embryos had expanded a bit more (especially the Grade 2) and then select the embros with the best developmental potential. As the blastocyst cavity expands, the inner cell mass containing the stem cells becomes visible and may be graded based on the size and number of stem cells present (A is good, D is bad). The size of the inner cell mass and the number of stem cells present reflect the developmental potential of the embryo, in that the stem cells form the baby. Very few stem cells is not a good sign and may result in a "chemical" or "empty sace" pregnancy


Deb - April 1

Dr. Smith,
I am planning on having an FET in the next couple of months. I have 2 blasts frozen 4AA (was a 8cg3) & 4BB (was a 7cg3). I know nothing can be for certain but I have read so many different things about survival of the embryo when thawed. I read one thing which makes me feel positive & then I will read something different & feel so discouraged. I am trying to relax so I am not so stressed so I am hoping you could give me a clue about if these are good embryos or not. Thank you so much!!


Dr Smith - April 1

Provided the lab has experience freezing and thawing blastocyst stage embryos, they should suvive. The main reason blastocyst stage embryos don't survive the freeze-thaw process is because they were of poor quality to begin with (not all blastocyst stage embryos are created equal - that's why we grade them). Your embryos received the highest grade, so I'm reasonably confident that they will make it. Best of luck with the FET.


scandigirl - September 14

Dr. Smith,
I just completed a DE cycle. The donor produced 22 eggs, 14 mature, 9 fertilized, 5 made it to day 3, on day 5 two "grade 3" (scale is 1-3, 3 being worst) blasts were transferred and 2 morula left to day 6 to grow and potential freeze (didn't). My questions are - how well did this donor produce ? I have no reference for the numbers. And how does the grade 3 blasts impact chances for success? The clinic has a 67% DE succes rate.
Thank you!


Dr Smith - September 15

When donated eggs are used, 50-60% of the embryos should make it to the blastocyst stage with majority be of top quality. Based on your post, this donor did not measure up in terms of quality (quanity was O.K.). There are a few explanations. (1) Life is like a box of chocolates... Athough a first time donor may look good on paper, E2 levels and U/S, the quality of the eggs cannot be ascertained until the eggs are fertilized and the embryos cultured to the blastocyst stage. We have also seen this kind of substandard development in our donor program (see footnote). (2) Poor quality sperm (i.e. excessive DNA fragmentation) can negatively affect embryo development to the blastocyst stage and the quality of the resulting blastocysts. If there was a contributing male factor, this may the reason. (3) The stimulation was mismanaged - unlikely, but possible. (4) Substandard lab conditions - again, unlikely with a DE rate of 67%, but possible in your specific case.

Your chances are significantly dimished from 67%. The other problem with low grade blastocysts is that are more likely to cause "chemical" and "empty sac" pregnancies. There are not enough stem cells in the low grade blastocysts to continue development.

Footnote: In our program, we can identify with the recipient's disappointment when only poor quality embryos are available for transfer in a DE cycle. In our minds, once you have accepted using DE (and that always a difficult decision) you are depending on us to give you the best chances of success by adequately screening the donor to minimize this kind of situation. So, it is our policy to guarantee at least two good quality blastocyst stage embryos for transfer in a DE cycle. If we find ourselves in the same situation as you (and it does happen occasionally because you just never know on a first time donor), we perform another DE cycle for free. This reduces the stress experienced by the recipient couple. As far as I know, we are the only program that does this.


scandigirl - September 17

Is there any way to test for poor sperm quality? ICSI's was performed. This donor has two biological children under 5 yo. Just trying to figure out where to go from here. Also, with a chemical pregnancy, will the beta hcg levels rise as normal? At what point is a chemical pregnancy defined?
Thank you so much for your honest answers.


Dr Smith - September 19

The routine semen analysis evaluates the basic sperm parameters, but only tells us so much. Recent research suggests that excessive DNA fragmentation may play a role in early embryonic demise as well as first trimester miscarriage (chemical and empty sac pregnancies). For more information on perm DNA fragmentation and its clinical significance, see

Generally speaking, a chemical pregnancy is defined as positive pregnancy tests, followed by an abnormal rise in hCG. The hCG rises slowly, peaks in a few days to weeks and then declines. A chemical pregnancy occurs when the embryo implants in the endometrium, releases hCG, but does not continue to develop because (1) the embryo is genetically abnormal (i.e. does not have enough stem cells, or (2) the endometrium fails to provide a hospitable environment for continued embryonic development.


scandigirl - September 21

I am the one that received two grade 3 blasts transferred. Had my day 9 hcg come back at 124 and day 11 at 273. I know you said there is a higher rate of blighted ovum with lower grade blasts. Do the hcg results make that less likely ? What is the % of time someone has good and doubling hcg levels and then no heartbeat at 6 weeks?
Thank you.


Dr Smith - September 22

Your hCG levels are appropriate for Day 9 and Day 11. No worries there. You are referring to "empty sac" pregnancies where the hCG rises appropriately, but there is no fetal heartbeat at 6 weeks. This happens in about 8-10% of IVF pregnancies when embryos are transferred on Day 3. This is reduced to approximately 3-5%, if only blastocysts are transferred (our own unpublished data) If only good quality blastocyst stage embryos are transferred, this can be further reduced to less than 1% (again our unpublished data). So, by subtraction, the chances of an "empty sac" pregnancy due to transferring poor quality blastocysts is about 2-4%. This is still considerably less than with Day 3 transfers. That means, when a pregnancy results from a blastocyst transfer (even of poor quality) there is a 95-97% chance of term pregnancy. Cautious optimism is in order.



hepburn - April 24

Dr Smith
I had an IVF cycle two years ago, which was very lucky to get 6 blastocysts all of good grading. The fresh implant was successful at that stage. My dr believes in one egg at a time.
With 5 of them frozen we thought we would try for another baby. First cycle was in march, the 1st blastocyst was defrosted the night before only to die in the morning. They defrosted another 2 hours prior to the procedure. It had fully expanded, but was showing promising signs. That cycle only proved to be an emotional rollercoster with no result.
April cycle they defrosted the blastocyst the night before, by the time of transfer the blastocyst had fully expanded. Does this improve my chances of success



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