| Table 4. Istanbul Consensus Scoring System for Blastocysts |
| |
Grade |
Rating |
Description |
| Stage of development |
1 |
|
Early |
| 2 |
Blastocyst |
| 3 |
Expanded |
| 4 |
Hatched/hatching |
| ICM |
1 |
Good |
Prominent, easily discernible, with many cells that are compacted and tightly adhered together |
| 2 |
Fair |
Easily discernible, with many cells that are loosely grouped together |
| 3 |
Poor |
Difficult to discern, with few cells |
| TE |
1 |
Good |
Many cells forming a cohesive epithelium |
| 2 |
Fair |
Few cells forming a loose epithelium |
| 3 |
Poor |
Very few cells |
| (Alpha Scientists in Reproductive Medicine & ESHRE Special Interest Group of Embryology, 2011). |