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Understanding embryo grading in the IVF process
The goal of an IVF protocol is to create as many embryos as possible, given the patient's age and viability of their egg and sperm. Every fertility clinic strives to achieve the highest fertilization and blastulation rate. Technologies and the professionalism of embryologists are among the main influencing factors.
Embryo grading is a representation of an embryo's visual characteristics observed through a microscope during the embryo culture stage. Morphology (visual look) is one of the factors that inform the specialist of the embryo's potential.
At NGC, embryo development is precisely controlled by Embryoscope incubators that use an advanced micro camera setup. Embryo grade is proposed via an AI scoring system and verified by an embryologist on the screen. As a result, the embryos are not exposed to temperature and gas fluctuations associated with removal of culture dishes from the incubator.
Section 1: The IVF Process and Embryo Development
Step-by-Step: A Brief Overview of IVF
An IVF procedure requires several ultrasound screenings (monitoring) followed by the final injection and egg retrieval procedure. As soon as the eggs are taken from the woman’s ovaries, fertilization (IVF / ICSI) is conducted in the embryology lab. During the next 6 days, embryo growth will be carefully assessed and recorded. The resulting embryo may be transferred in the uterus, as well as biopsied for genetic screening and cryopreserved.
Early Embryo Development
Early embryo development begins with fertilization, where the sperm and egg unite to form a zygote. Over the next few days, the zygote undergoes a series of cell divisions, known as cleavage, to form a multicellular embryo. By day 3, the embryo typically consists of 6-8 cells. During this stage, embryologists assess the number of cells, symmetry, and fragmentation to determine the embryo's quality. By day 5-6, a blastocyst is formed, which has its own set of assessed parameters, including Embryoblast (or Inner cell mass) and Trophoblast (or Trophectoderm).
Grading Criteria: What Factors Are Evaluated?
Each human embryo has a set of characteristics that can be seen and evaluated.
(1) Number of cells. An embryo should consist of a specific number of cells during the cleavage stage
(2) Symmetry and structure of cells. Size and shape of cells indicate development specifics
(3) Fragmentation level. The parameter is measured based on how many pieces of cellular material break off during cell division
When assessing blastocysts (Day 5-6 of development), it is necessary to evaluate the following parameters:
- Expansion level which indicates the size of the blastocyst. The parameter is graded 1-6, where “1-2” represents an early blastocyst, while “6” stands for a blastocyst which has fully hatched from its Zona Pellucida (ZP), or its glycoprotein outer layer. ZP can also be purposefully removed during assisted hatching of blastocyst, i.e. when it is necessary to take a biopsy for PGT-a
- Inner cell mass and Trophectoderm. ICM cells will form a fetus, and TE cells will form a placenta. Both are graded “A”, “B” or “C”, where “A” indicates the best condition
Factors Influencing Embryo Grade: Age, Lifestyle, and Other Factors
Embryo grades reflect various aspects of the patient’s individual situation such as age, genetics, lifestyle choices etc. Patients older than 41 may usually expect embryos with lower grades due to decreasing egg quality. The lifestyle choices of both partners, such as smoking, alcohol consumption, lack of rest and unhealthy diet can also negatively impact the number and quality of their embryos.
Beyond the Numbers: The Importance of Individualization
IVF outcomes largely depend on the age and health background of the patient, so it is normal to expect different embryo culture outcomes in every case. It is recommended not to overestimate the importance of embryo grades. Each embryo may have a potential not determined by the standardized review of morphology. It is not rare that success is achieved with "BC"-graded embryos that are typically considered the weakest. As long as you have blastocysts for testing and transferring, you may succeed.
Section 5: What to Do Next: Moving Forward After Embryo Grading
Choosing the Best Embryos for Transfer
This decision is based on embryo grade and genetic testing results (PGT-a). In NGC, we also consider separate scores provided by Embryoscope’s AI which range from 1 to 10 (where 10 is the highest rating).
NGC’s team adheres to the current treatment guidelines that recommend single embryo transfer. According to scientific publications, transferring two euploid embryos is not beneficial to success rate, and in fact may jeopardize the pregnancy if both embryos successfully implant.
Discussing Options with Your Doctor
Your fertility doctor is the first instance you should contact to discuss your embryo culture report and grading. Instead of diving into forum articles where facts are often mixed with emotions, consider asking for clarifications from your main ally.
Managing Expectations and Finding Support
IVF may easily become a true emotional rollercoaster. Adjusting expectations and building trust with your doctor are important steps on your way to success and inner peace. Remember that each patient's journey is unique, and success can come in many forms: A healthy pregnancy may develop despite a poor embryo grade.
