Do you undergo ICSI or IVF? Surely you have many questions, and in this article we will give you an explanation about the quality of embryos.
What do we mean by degrees of quality of embryos? Is it possible to predict pregnancy success according to the quality of the embryos? Answer these questions and more details in the following article:
Embryo quality scores: what do they mean?
Many couples resort to assisted reproduction methods, such as: ICSI, and after the process of withdrawing the eggs from the woman, they are fertilized with sperm, then the quality of the embryos is studied, and they are classified according to the degrees of their quality.
The importance of categorizing the quality of embryos into grades lies in knowing which embryos will be returned to the womb or that will be frozen, and to determine the number of embryos to be returned, in addition to determining the best day for return.
The embryos are classified after leaving them for the third or fifth day, and the classification process is based on factors such as: the mass of the inner cell, the degree of expansion, and the formation of the ectoderm, which are the cells that form the outer layer of the blastocyst and are responsible for delivering nutrition to the embryo.
Embryo Quality Scores: What are the scores?
The embryos are classified for the first time on the third day of the egg retrieval process, we will now explain the embryo quality grades:
1. Classification of embryos on the third day
The third day is referred to in embryology as the cleavage stage This is because the cells of the fetus divide and increase in number, but the size of the fetus does not increase.
The embryos are divided into grades at this stage depending on the number of cells and their appearance under a high-powered microscope. The embryos are classified into four grades and numbers from one to four are given.
It is worth mentioning that good embryos on the third day consist of 6 to 10 cells, with a healthy appearance, without fragmentation between the cells. The fragmentation occurs as a result of the accumulation of remnants of cells that do not contain a nucleus or remnants of the decomposition of one or more cells.
The grades of embryo quality can be clarified and described in the following table
degree of fetus
the description
Grade 1
Cells are of equal size, without segmentation
Grade 2
Cells are equal in size, having slight fragmentation
Grade 2.5
Cells are mostly equal in size, moderately fragmented
Class 3
Cells of unequal size, no fragmentation to moderate fragmentation
Class 4
Cells of equal or unequal size, moderate to severe fragmentation
2. Classification of embryos on the fifth day
The embryo on the fifth day is called a blastocyst, where the embryos continue and the number of cells continues to increase, but the cells begin to grow and differentiate as well.
There are two types of cells at this stage: cells that will develop and grow to form the fetus, and cells that grow and develop to form the placenta and other tissues that the mother''s body needs for pregnancy.
The classification on the fifth day is complex and can change depending on the status of the case, but it depends on the following factors:
The extent of the blastocyst, and its grades range from 1 to 6, and grade 6 is the most advanced.
The quality of the cells that will develop into the fetus, and their grades range from A to C, and grade A is the best quality.
The quality of cells developed into the placenta ranges from A to C, with grade A being the best quality.
embryo success rates
After we have clarified the degrees of embryo quality, we will now explain the expected success rates for each degree:
The success rate for embryos in the first degree may be 65%.
The success rate for second-degree embryos may reach 50%.
The success rate for embryos in the third degree may be 33%.
It is worth mentioning that the classification of embryos is not a solution to fertility problems, as it is possible for some embryos on the third day that have a low score to develop on the fifth day and become of a higher grade and with a higher success rate as well.
