It seems a bit stupid to ask this question in 2021! Embryo culture is a process of elimination. From oocyte retrieval, fertilization to embryo development, every stage is a survival of the fittest. Back in 2010, the concept at that time was like this: blastocysts have a higher pregnancy rate, ectopic pregnancy, and miscarriage rates are lower. At that time, the most worrying thing is“the failure of culture to blastocyst”. Some people said that ”the uterus is the best incubator, and it should be implanted as soon as possible”. This sounds reasonable at first, but after thinking about it thoroughly, “the early embryos are still in the fallopian tube, doesn't it need to be implanted in the fallopian tube?" We, Stork Fertility Center, did a lot of TET (Tubal Embryo Transfer) more than ten years ago, and the pregnancy rate was up to above 50%. Compared with only 30% when implanted in the uterus, these two practices are poles apart in pregnancy rate.
Reverse thinking: is it correct to transfer in a hurry since worrying about the failure of culture to blastocyst? In fact, a certain percentage of embryos die after implantation. Aren't these people using themselves as "clinical trials"? Waiting 15 days for a failed pregnancy for an unknown reason, and don't know how to improve next time. Then, we can only do the treatment in the same way. Therefore, we often say that the most expensive thing for doing IVF is "the pain of unexplained pregnancy failure".
What do we learn from this case?
Worry about the failure of culture to blastocyst, therefore transfer in a hurry. Stop burying your head in the sand. Rather than experience "unexplained pregnancy failure", it is better to find a way to construct an excellent "culture system".
Our experience in culturing blastocysts is as following:
Blastocyst transfer has ruled out the variations that the embryo cannot grow to blastocyst. If a failed pregnancy, it can be more accurate to speculate that there are other invisible causes, such as embryo chromosome abnormalities or autoimmunity and thrombosis.
