IVF and Embryo Grading

IVF and Embryo Grading

In vitro fertilization, a type of assisted reproductive technology that has been used mostly for the couple who face difficulty in conception and achieving a healthy pregnancy for a complete term. There are different in vitro fertilization (IVF) techniques that have been developed throughout the years. One of these techniques of IVF involves how to choose an embryo that would help in the delivery of a healthy baby.

There is a separate grading system for sperms, eggs and embryos. Embryologists generally determine the best quality of an embryo based on the morphology or the appearance of an embryo after the fertilization is complete. The IVF center in Hyderabad can give you more clarity about how the grading is done.

Egg Grading

The grading system for the embryo is a complex process that usually starts at the time of egg retrieval and continues throughout the early embryonic development.  During the in vitro fertilization treatment, approximately 80 percent of mature eggs are retrieved. Only mature eggs will be fertilized successfully.

The Day of Egg Retrieval (Day 0)

The first stage in the egg retrieval is the fertilization of a healthy mature egg. There are two ways to fertilize an egg:

  • Microdroplet


During this microdroplet procedure, around one hundred thousand sperms are dropped on the egg for fertilization. In this procedure, it is difficult to determine the time when the egg is matured. Your infertility specialist will know the whether the egg is mature or not once it is fertilized.

  • Intracytoplasmic sperm injection (ICSI)


Unlike microdroplet technique, during ICSI, a normal and healthy sperm is selected and injected into the egg for fertilization. The embryologist will prepare the egg in the laboratory condition by denuding or stripping the egg of its supporting cell. The embryologist can then tell us whether the egg is mature and has the potential to fertilize and results in a healthy embryo.

The average fertilization rate with in vitro fertilization is 70-75 percent.

Day 1

The embryologist will determine which egg is fertilized the next morning after the beginning of an IVF treatment. The grading score is based on the number, position and size of the pronuclei. Two nuclei are involved in this procedure, one from the sperm and one from the egg. The nucleus should be equal in size and must be located in the center of the egg.

Pronucleus comprises of several small structures called nucleolar precursor bodies (NPB’s) that should be lined up with one another. A “halo” is generally formed around the two nuclei that are composed of a fluid called cytoplasm.

Day 2 & 3

On the day 2, the embryos are scored based on the number of the cells, number of nuclei and cell size evenness. The embryo should be ideally made up of 4 cells and each cell should comprise of one nucleus. Cells that have multiple nuclei are considered to arise from an abnormal embryo.

The embryo is graded based on the size. The more equals the size, the higher the grading scores. Only day 3 the cells are graded based on the three-dimensional distribution of cells.

Day 4 & 5

On day 4, embryologist generally does not evaluate the embryos as many changes happen at this stage and it is difficult to score. On day 5 embryo reach a blastocyst stage. To reach this stage, the embryo has to undergo compaction to form the blastocoel.

The formation of blastocoel starts around day 3 or 4 when the embryo was in 8-16 cell stage. The blastocoel is a fluid-filled structure that helps in separating the trophectoderm and inner cell mass. The cells that make up the trophectoderm become the placenta.

Consult Hegde fertility-best IVF center in Hyderabad to know more about the grading system. An increased IVF success rate is reported under the supervision of experienced IVF specialist. Dr. Vanadana Hegde is the best IVF specialist.

Leave a Reply