Slow growing embryos /arrested before blastocyte
1 Replies
helene - October 9

Dear Dr. Smith,

I’ve been blowing this site for these days after my first IVF try. It’s been a great pleasure reading all you posts.

I am 35 (DH 36), no previous pregnancy, dx as unknown infertility. 9 eggs were retrieved, after ISCI, 5 of 9 fertilized. My Dr. called on day 2 saying we should be prepared on a day 3 transfer since we don’t have many embryos to wait too long in vitro. On day 3, we got a call form Dr said that all 5 embryos were slow growing (2 4-cell, 2 3-cell, 1 2-cell stages for 5 embryos respectively) and proposed for a day 6 transfer. Today (day 6) I got another call from my Dr. that all 5 embryos were arrested around the stage between multi-cell stage to blastocyte so there were no embryos to transfer for this cycle. This is all I know after retrieval.

My questions to you:

1.   All the embryo had been growing/dividing slowly as we can see from stages on day 3. To me it is quite possible that these embryos just arrived the stages as the results of slow growing other than arresting. Is there a clear line to distinguish these two processes according to your expert experiences? If there is no clear line there, would you rather go ahead to do the transfer or cancel the cycle as my Dr did?

2.   what are possible reasons for the arresting at this stage? If we wanna do another try, what are possible approaches to prevent this happening again? I understand biologists using some chemicals to arrest cells at G2 stage, is the arresting here on embryos more due to the culture medium or replication machinery in embryos? The reason I am asking this is that if this is more due to culture (we don’t know exactly embryos needs at the sage), will transferring earlier (day 3 other day 5) be a possible mechanism to prevent this?

Your thoughts would be greatly appreciated




Dr Smith - October 10

If an embryo fails to progress for 48 hours or more, it has arrested development. By comparison, an embryo that continues to divide, but more slowly than the anticipated rate, may still be considered viable. In your case, the embryos had arrested prior to compaction (a process the embryo must undergo before becoming a blastocyst). They were more than 48 hours behind in development. I agree with your doc to cancel the transfer. Because of the slow growth throughout, it is likely quality of the eggs was poor on this particular cycle.

Embryos may grow slowly or arrest because they failed to complete cytoplasmic maturation while still in the follicle. When this is the case, changing the protocol can adjust the rate of growth of the follicles and improve egg maturation.

Another reason embryos arrest development is that they are genetically abnormal. Between the 4- and 8-cell stage of the development, the embryonic genome becomes active (before the 4-cell stage, there is no genetic activity - the embryo is on autopilot). If there are abnormalities in the embryonic genome, the embryo simply stops growing. Nature is very efficient. If there is a genetic problem, as soon as it is detected, embryonic development is terminated.

With these two explanations in mind, it is unlikely that culture conditions would change either of these situations. Replacing the embryo to the uterine environment would not change the cytoplasmic maturity or the genetic make up of the embryo. The days of suboptimal embryo culture conditions (thankfully) are well behind us now.



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