Embryo Quality

Embryo Quality Classification – Comprehensive Guide

What is Embryo Quality?

Embryo quality is the assessment of an embryo based on its morphological characteristics under a microscope. It is an important parameter in predicting the chance of pregnancy, but not sufficient on its own.

1. Cleavage (Day 2–3) Embryo Assessment

During this period, embryos are assessed based on cell number, symmetry, and fragmentation rate.

Assessment Criteria

• Cell number (ideal: 6–8 cells on day 3)
• Cell symmetry
• Fragmentation rate

Quality Classification

• Grade A: Symmetrical, no/very little fragmentation
• Grade B: Mild fragmentation (10–20%)
• Grade C: Moderate fragmentation (20–50%)
• Grade D: High fragmentation (>50%)

2. Blastocyst (Day 5) Classification

The most commonly used system is the Gardner & Schoolcraft classification.

Blastocyst Assessment Parameters

1. Degree of expansion (1–6)
2. Inner cell mass (ICM)
3. Trophectoderm (TE)

Degree of Expansion

• 1: Early blastocyst
• 3: Full blastocyst
• 5–6: Hatching / hatched

ICM (Inner Cell Mass)

• A: Dense and compact
• B: Moderate
• C: Poor

TE (Trophectoderm)

• A: Many regular cells
• B: Moderate quality
• C: Low quality

Example Embryos

• 5AA → Best quality
• 4AB → Very good
• 3BB → Moderate
• 2BC → Low quality

Clinical Significance

Morphological quality is related to the chance of implantation, but genetic makeup (PGT) and patient age are more decisive.

Important Note

A good quality embryo does not always mean a healthy embryo. Therefore, a holistic assessment is required.

Conclusion

Embryo quality is an important factor affecting IVF success. However, it is not the sole determinant and must be evaluated together with other clinical parameters.