IVF and embryo grading: how it works

What is IVF?

Couples with blocked or damaged fallopian tubes, male infertility (like low sperm count or sperm with low motility), ovulation disorders, ovarian failure, uterine fibroids, or unexplained infertility may seek out in vitro fertilization. IVF is a fertility treatment option that allows couples to carry their children after they are unable to conceive naturally.

After egg and sperm retrieval, they are combined in a laboratory to create an embryo. Then, a number of embryos are inseminated back in the uterus to hopefully result in a healthy pregnancy.

However, there are some IVF side effects. The procedure may result in discharge, mild cramping and bloating, constipation, breast tenderness, or bowel/bladder damage, infection, or bleeding. The hormone treatment that precedes the procedure may result in headaches, mood swings, abdominal pain, hot flashes, and bloating.

If the IVF treatment is successful, the couple should be prepared for the increased likelihood of multiple pregnancies as well as ectopic pregnancies (especially when the woman has damaged fallopian tubes). IVF may also result in a child born premature or with low birth weight.

What is Embryo Grading?

For all you over-achievers out there - no, unfortunately embryo grading is not a way for your embryos to earn an A+.

After the egg and sperm are combined in the laboratory, they are observed and given a “grade” to ensure that the embryo transfer goes smoothly, and that the embryos inseminated are healthy and likely to result in a pregnancy.

On Day 3, the embryos are in their “cleavage stage,” which means that the cells are actively dividing. That fragmentation is what the specialists are looking for when they grade your embryos. The grade descriptions below were found via ARC Fertility:

      Grade 1: Cells are of equal size; no fragmentation seen

      Grade 2: Cells are of equal size; minor fragmentation only

      Grade 2.5: Cells are mostly of equal size; moderate fragmentation

      Grade 3: Cells are of unequal size; no fragmentation to moderate fragmentation

      Grade 4: Cells are of equal or unequal size; fragmentation is moderate to heavy

Days 5/6 are more important, however, because this is the “blastocyst stage.” Embryos in this stage have a higher chance of implanting, which means you’ll need to implant fewer and the chance for multiple pregnancies decreases. Embryos that reach this stage also have a lower rate of chromosomal disorders. The grade descriptions below were found via Atlanta Infertility:

      Grade 1:The embryo has the appropriate cell number for stage development and the cells are even in their size and shape. The embryos should have little or no fragmentation between cells.

      Grade 2: The embryo has the correct development of cell numbers, with a small amount of fragmentation, or slight unevenness of blastomere sizes.

      Grade 3: The embryo contains blastomeres that are uneven in size and has more than 30% fragmentation. Embryos developing slowly will also receive a grade of 2 or 3 even if they are normal otherwise.

      Grade 4: The embryo contains very few, if any, viable appearing cells and has a high percent fragmentation.

The grade is based on a few other things in addition to fragmentation. Embryo expansion means their size and how it correlates to the fragments below (similar to their density - a large embryo with few fragmentations inside isn’t very strong). The inner cell mass specifies the most desireable cells that will eventually grow into a baby. The trophectoderm, on the other hand, specifies the most desireable cells that will eventually grow into the placenta and will initiate the implantation to the uterine wall.

Written by: Joanna Hynes

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