Blastocyst Grading System


This grading scale was created by Dr. David K. Gardner.
Once fertilized, embryos will continue to develop in our laboratory for up to seven days. The embryo grading process assesses embryo quality and requires a vast amount of training and skill. Our embryologists use their experience to grade the embryos in order to select the best embryo for transfer, hopefully increasing the odds of a successful pregnancy.

A blastocyst is the most advanced stage an embryo can achieve in culture and typically occurs 5 – 7 days post fertilization. Only the best quality embryos develop to the blastocyst stage. A blastocyst has two distinct cell types and a central cavity filled with fluid:

Number describing overall expansion of the fluid cavity

Initially blastocysts are given a numerical score from 1 to 6 based upon their degree of expansion and hatching status. This part of the assessment can be performed on a dissection microscope.


Early Blastocyst

Blastocoel < half the volume of the embryo



Blastocoel > half the volume of the embryo


Full Blastocyst

Blastocoel completely fills the embryo


Expanded Blastocyst

Blastocoel volume is now larger than that of the early embryo and the zona is thinning



Embryo has breached the zona pellucida and is hatching out of its shell



Embryo is completely hatched

Letter Grade for Inner Cell Mass

The second step in scoring the blastocysts should be performed on an inverted microscope. The development of the inner cell mass (ICM) can then be assessed. The ICM is given a letter, the highest score being an A.

Letter Grade for Trophectoderm

The third step in scoring the blastocysts should be performed on an inverted microscope. The development of the trophectoderm can then be assessed. The trophecoderm is given a letter, the highest score being an A.

Additional Embryo Assessment Tools


Embryo grading is much more than the embryos’ isolated appearance. It also includes their morphokinetic development as witnessed via the EmbryoScope®.

Learn more about the EmbryoScope®

Pre-Implantation Genetic Testing (PGS)

The chromosomal status of an embryo can be determined with pre-implantation genetic screening which evaluates all 46 chromosomes within a few cells carefully removed from each embryo. This tool provides information regarding the chromosomal health of the embryo.

Learn more about PGS

Lab Research at RAD

RAD’s IVF Lab Featured its Embryo Research at ASRM

RAD’s IVF Lab was selected to feature their embryo research at the Annual Meeting for the American Society for Reproductive Medicine (ASRM). In their research, the RAD team set out to determine if the quality of the blastocysts correlates to the chromosomal status of the embryo. Learn more here: 

RAD’s IVF Laboratory Research (Publications, Oral Presentations, & Poster Presentations)

RAD’s IVF Lab has been an active member in the research community and has produced a number of publications, oral presentations, and poster presentations. For a complete list of all of RAD’s research, click here:

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Newark Office

4735 Ogletown-Stanton Road
M.A.P. 2, Suite #3217
Newark, DE 19713
Phone: (302) 602-8822
Fax: (302) 602-8832


Wilmington Office

Silverside Medical Center
2700 Silverside Road, Suite 2A
Wilmington, DE 19810
Phone: (302) 602-8822
Fax: (302) 602-8832


Dover Office

Eden Hill Medical Center
200 Banning Street, Suite 240
Dover, DE 19904
Phone: (302) 602-8822
Fax: (302) 602-8832


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