After Your Egg Retrieval: Updates From the Lab

This information will help you understand the updates you will receive from the Embryology staff after your egg retrieval. Please remember that embryo grading is simply a tool that your physician uses, along with your individual information, to determine the appropriate number of healthy embryos and optimal day for transfer. 
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The day of egg retrieval is considered to be Day 0. Depending on your treatment plan, you will receive additional updates about your eggs and/or embryos after your retrieval, as well as the date for your transfer, if applicable. 

Day 0

On the day of your egg retrieval, you will be told the total number of eggs retrieved before you go home. This number includes mature and immature eggs. 
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Some eggs may be partially degenerated (damaged or of compromised quality) or completely degenerated at the time of retrieval. These eggs may be included in the total egg count, but they cannot be fertilized or frozen. 
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After retrieval, the eggs are placed into an incubator until they are checked for maturity. A mature egg is one that has resumed meiosis and can be fertilized. 

Day 1

If you are freezing eggs, you will be told on Day 1 how many eggs were mature and how many eggs were frozen. 
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If fertilizing the eggs with sperm to make an embryo, the embryologist will “fertilize” all viable eggs, and you will continue to receive updates. When eggs fertilize normally, they have two nuclei (one from the egg and one from the sperm). These are called 2PN or zygotes. When there are fewer or more than two nuclei present, these embryos will not become normal embryos and will not be counted toward the total number of eggs fertilized. 

Day 2 – 3

Embryos at Day 3 are scored based on their morphology under the microscope. In our lab, embryos are scored on a scale of 1 to 3, where 1 is considered the best, based on the following characteristics:

• Cell division and symmetry: An embryo should have completed two rounds of cell division (four cells total) by Day 2, and three rounds of cell division (8 cells total) by Day 3, with one nucleus present in each cell. Each cell should be symmetrical and all cells should be roughly the same size.  
  
  
• Fragmentation: An embryo should have little to no cellular debris present. The more debris present, the less likely the embryo is to create a live birth.  
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Embryos with the correct number of symmetrical cells and with little to no fragmentation are scored as a “1/1” and usually have a good chance of further development. 

Day 5 – 6 

Blastocysts consist of different cell types. The inner cell mass sits inside a fluid-filled sphere surrounded by trophectoderm. Both of these cell types are necessary to establish a successful pregnancy.  

Developing embryos should reach the blastocyst stage by Day 5 or Day 6. In our lab, blastocysts are scored on a scale of 1 to 3, where 1 is considered the best based on the following characteristics:  
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• Inner cell mass: The stem cells that eventually become the fetus should be tightly packed and form a round ball.
  
  
• Trophectoderm layer: This is the outer ring of cells that will eventually become the placenta. These cells should be well-formed and equal in size.

Next Steps

Embryos or blastocysts are either transferred to a uterus, frozen or discarded based on the treatment plan that your physician discussed with you. We will continue to provide updates to you either through the MyNM Patient Portal or phone calls.  Please don’t hesitate to reach out to your treatment team with any questions or concerns.