FAQS ON EMBRYO GRADING FROM A DENVER FERTILITY CENTER

What Is Embryo Grading?

After the fertilization of oocytes with sperm in the IVF lab , the fertilized eggs (embryos) are stored in the laboratory for about 5 days before being implanted into the uterus.

Before the transfer, the embryos are first “graded”  to select the best ones that can be used for the implantation process.

The embryologists will use the following major criteria to select the high-quality embryos on or after day 5.

The total number of cells an embryo has: Good embryos will generally have six to eight cells after three days of growth. Those with fewer cells are still good, but they have little chance of attaining normal development.

Embryo fragmentation: Fragmentation is described as how an embryo splits into fragments. Small amount of fragmentation is generally normal, but excess fragmentations imply the embryo may have a low chance of attaining normal development.

Embryo Grading Day 3

Fully grown day 3 embryos are referred to as cleavage stage embryos. They means that the cells in the embryo are dividing but the embryo is not growing or increasing in size. The genetic material found in the embryo replicates thus the cells divide, but the total size of the embryo do not differ from that of an unfertilized egg. As the cleavage embryo divides, there is a small portion of cytoplasm that breaks off and forms some fragments. A process called fragmentation. The main cause of fragmentation is not really understood completely, but most people think that embryos contain a lot of fragmentation have limitations since the embryos may lose a lot of cytoplasm needed to sustain the cell.

Embryo Grading at Day 5

Day 5 embryos are also known as blastocyst stage embryos. During this stage, the embryo must be in a position to reach before it can implant on the uterus. Immediately the embryos reaches the blastocyst stage, the cells starts to divide. Afterwards, the embryos organize themselves into two distinct parts, the inner cell mass and trophectodem cells which are needed to sustain the pregnancy. The blastocyst is graded based on the three components of the blastocyst embryo. The three major components are graded to describe the expansion, the mass development of the inner cells, and the quality of the trophectoderm cells.

How effective is embryo grading?

Embryo grading combined with the patient’s history of their fertility and age is used to help the embryologist to establish the perfect day to carry out the transfer. It is also used to determine which embryos to transfer.

After observing how the embryos are developing, the doctor will use this information to counsel the IVF patients and also determine the number of embryos to be used on the patient.

Embryos are transferred to the womb at different times during their growth. This allows the doctor to choose the best embryo that can be used in this procedure. In some cases, the embryos can be selected on the second or third day a process referred to as cleaved stage as discussed above. The remaining embryos can be left in the laboratory until they reach the blastocyst stage which is around day five.

How do the embryologists make the final decision?

Using their skills and expertise, the embryologists are able to assess the embryos and select those that have a higher chance of implanting in the womb and which can continue with development.

This process is done by applying a grading system using the different criteria for each stage such as;

• The total number of the cells present
• The rate at which the cells are dividing
• Whether the division of cells is even
• Presence of any fragments of the cells used.

At this stage, different grading systems are used once they reach day 5 which is the blastocyst stage. Once the grading system is applied, the suitable ones are selected to be used in the transfer while others are stored for future use.