Embryo grading is the procedure used to determine which of the fertilized embryos that are created through in vitro processes are the best and most viable. The strongest candidates for fertilization (and continued growth) are the ones that are then transplanted back into the woman's womb in hopes of a successful pregnancy occurring. Embryo grading is an important procedure and one that can dramatically improve the odds of a pregnancy being a success. However, different techniques and styles in embryo grading can mean that different doctors are better or more efficient than others.
How Embryo Grading Works
Most eggs will be fertilized or will be unsuccessful after 24 hours or so from the time that they are mixed with sperm in the laboratory. A doctor will check on the eggs up until this time for signs of fertilization. If he sees fertilization signs for any number of different eggs, he'll spend the next 4 days or so monitoring them closely for signs of quality. A grading procedure typically takes place every 24 hours or so, although some doctors are more or less thorough than that. The doctor will examine each egg under the microscope for signs of: fragmentation (the uneven splitting of cells or the loss of certain cell components; higher fragmentation is an undesirable embryo quality), the size of the zona pellicuda, or the protective protein shell that helps to insulate the embryo from the outside world in the first days of development, even cell splitting and more.
At each reading of the embryo's quality, the doctor will assign a number grade to the embryo. When the embryos have developed into blastocysts and are ready for transplant, those embryos with the highest grade are deemed the most likely to succeed and are used first.
Variations in Techniques
The single greatest variation in embryo grading technique is the frequency with which the doctor grades the embryos. The more instances of grading, the more likely the doctor will be able to find the best embryos.
Another primary variation in the embryo grading technique is the style with which the doctor examines the eggs. Because fertilized eggs and embryos in the very earliest stages of development are unbelievably fragile, it's crucial that the doctor handle them properly. Any movement or jarring can cause the embryos to become permanently deformed or to die completely. Thus, the doctor must handle the embryos with the utmost care, including while he is observing them through the microscope. Some doctors also put higher value in certain qualities of the embryo over others. The single most important factor is typically the fragmentation of the embryo, although certain doctors disagree about the other qualities as well.
If you think that in vitro fertilization and embryo grading may be important tools for you and your partner to become pregnant, speak with a fertility doctor in your area for additional advice and to see if these are viable options for you.