Day 5 development of embryos are the preferred day for embryo transfer as it gives a better selection and higher pregnancy rates for patients
Sponsored by Fertility Specialists of Texas
Written by Dr. Carlos Guerrero,brPh.D., HCLD,brELD
Howbrdoes an embryologist select the best embryos for transfer?
This is a question that Ibram routinely asked by patients undergoing IVF treatment. If an embryologist hasbr10 embryos from a patient how do we know which one will be the strong one withbra high potential to implant and ultimately become a baby? To the untrained eye,brembryos will look very similar to each other. However, each embryo displaysbrspecific morphological criteria that will allow us to distinguish the ones thatbrare developing the best. This is why a very experienced embryologist isbrparamount for a successful IVF treatment cycle.
In many ways, IVF is likebrpacking many months of trying to conceive into one cycle, because of the manybrembryos that often result, but it increases the probability of success by selectingbrthe best embryo(s) from the group to be replaced.
There are two possiblebrembryonic stages for embryo transfer, one at the cleavage stage and one at thebrblastocyst stage. At the cleavage stage, the embryos are on either day 2 or daybr3 of development in the laboratory after the egg retrieval procedure. Thesebrembryos will have approximately 4-cells on day 2 or 8-cells on day 3. Embryosbrat these stages are more difficult to select between each other, as they lookbrvery similar. We use criteria such as the number of cells, the size of thebrcells and the amount of fragments inside the embryo to select the potentially bestbrone. However, embryos at this stage exhibiting high quality traits don'tbrnecessarily continue developing. There is a process called embryonic activationbrthat occurs around day 3 of development where the embryo actually startsbrproducing its own proteins for further development so if there is any problembrwith the egg or sperm that produced that embryo it will manifest after day 3brand the embryo will stop developing. Usually, about 60-70% of day 3 embryosbrwill continue developing to the blastocyst stage in world class IVFbrlaboratories. Laboratories with high quality embryo culture conditions willbronly transfer day 2 or day 3 embryos when all the embryos produced by a patientbrwill be transferred. In this case, if the patient only has 2 embryos they willbrbe transferred regardless of quality so the day of transfer won't matter as webrare not selecting any embryos.
Improved laboratorybrconditions have allowed us to grow embryos to day 5 of development called thebrblastocyst stage. This is the preferred day for embryo transfer at FertilitybrSpecialists of Texas' laboratory, as it will give us a much better selection ofbrthe embryos and provide our patients with higher pregnancy rates. Embryos atbrthis stage will have a different more complex morphology than embryos at thebrcleavage stage. Blastocysts have a fluid filled cavity where we will find abrcompact mass of cells called the inner cell mass. This mass of cells is whatbrwill become the baby. Also, we will find a layer of cells forming around thebrfluid filled cavity called the trophectoderm which will ultimately form thebrplacenta. Evaluating these components of a blastocyst will tell us which of thebrembryos is truly the best one from a group of embryos.
Our IVF laboratory atbrFertility Specialists of Texas has one of the best embryo culture conditionsbrallowing us to produce high quality day 5 blastocysts. This is one of thebrreasons we provide our patients with one of the highest pregnancy rates in thebrnation.
About Dr. Guerrero:
Dr. Guerrero isbroriginally from Colombia, South America. He is a graduate of Louisiana StatebrUniversity, where he received his Ph.D. degree in Reproductive Physiology withbremphasis in Embryology. Prior to joining Fertility Specialists of Texas, Dr.brGuerrero was a Senior Embryologist and Head of Research and Development at thebrTHR Presbyterian-Harris Methodist ARTS Program in Dallas-Fort Worth,TX .He isbrboard certified in Human Clinical Andrology and Embryology and is a HighbrComplexity Clinical Laboratory Director and In Vitro Fertilization LaboratorybrDirector by the American Board of Bioanalysis.