How Labs Ensure Quality Control During Embryo Grading
When your embryologist assigns a grade to your embryo, it's not just one person's opinion—it's the result of rigorous quality control systems designed to eliminate subjectivity and ensure reliable assessments. This behind-the-scenes look reveals how top IVF labs maintain consistency in their embryo evaluations.
The Multi-Layer Quality Control System
1. Standardized Grading Criteria
Laboratories adopt standardized grading systems, such as the Gardner and Schoolcraft systems for blastocyst evaluation, to maintain uniformity in assessments. These protocols provide clear criteria for evaluating embryo quality, facilitating consistent decision-making across different embryologists. In addition to standardized grading criteria, regular competency assessments are conducted to ensure that evaluations remain accurate and consistent.
All embryologists in accredited labs follow:
ASRM/ESHRE grading guidelines (universal standards)
Lab-specific SOPs (detailed protocols for edge cases)
Digital reference libraries (comparison images for each grade)
AAB (proficiency testing for city-wide inter-lab variability)
Example: A "4AA" blastocyst must meet 12 specific morphological criteria in our lab before receiving that designation.
2. Dual-Evaluator Verification
To minimize subjective biases, many laboratories employ double-checking procedures where multiple embryologists independently assess and grade embryos. Discrepancies are discussed and reconciled, leading to more reliable evaluations.
Every embryo is graded independently by two senior embryologists
Discrepancies trigger:
Third review by the lab director
Re-examination under higher magnification
Documentation requirement: All grades include the reviewer's initials
3. Daily Calibration Exercises
Morning "grading drills" using:
Archived embryo images (known outcomes)
Time-lapse videos for developmental context
Blind grading tests 2x/month (staff must match the director's grades on 20 samples)
Technology Enhancing Objectivity
The integration of time-lapse imaging and artificial intelligence (AI) technologies has revolutionized embryo assessment. Time-lapse systems enable continuous monitoring of embryo development, providing detailed data that enhances grading accuracy. AI algorithms assist in analyzing this data, offering objective evaluations and reducing human error.
AI-Assisted Grading Systems
Computer vision algorithms:
Measure cell symmetry to 0.1μm precision
Calculate fragmentation percentages
Flag potential grading discrepancies
Current use: Second-opinion tool in 38% of U.S. labs (SART 2023 data)
BELA - Weill Cornell Medicine tried this system
Vitrolife’s iDAScore - Involves using their Embryoscope Time-Lapse Incubators
Time-Lapse Monitoring
Eliminates snapshot bias by:
Tracking division patterns (not just static appearance)
Recording the exact timing of developmental milestones
Proven impact: Reduces inter-embryologist variation by 41% (Fertility & Sterility, 2022)
Continuous Quality Improvement
Ongoing quality audits are conducted to monitor grading practices and identify areas for improvement. Feedback mechanisms and continuous education ensure that embryologists stay updated with the latest advancements and maintain high standards in embryo assessment.
Outcome Audits
Monthly reviews comparing:
Predicted potential (based on grade)
Actual implantation rates
Adjustment protocol: If a specific grader's predictions are >15% off, retraining occurs
External Proficiency Testing
Laboratories comply with established guidelines from authoritative bodies. These agencies require quarterly tests to ensure labs remain within the correct standard of embryo grading.
Quarterly challenges from:
CAP (College of American Pathologists)
ESHRE certification programs
Grading accuracy benchmarks: Must maintain >90% concordance
What This Means for Patients
Your embryo grade reflects consensus - Not just one person's judgment
Labs track grader performance - Poor predictors are retrained
Technology reduces human error - But final decisions remain expert-driven
Real-world impact: In our lab, this system reduced grading inconsistencies from 22% to 6% over 3 years.
Questions to Ask Your Clinic
✔ "How many embryologists review each embryo grade?"
✔ "Do you use AI or time-lapse verification?"
✔ "What's your inter-grader concordance rate?"
✔ "How often do you audit grading accuracy?"
At the end of the day, grading is still a subjective process that could be improved. The grading criteria are too generic and do not leave much room for precise grading. We believe it is because the morphological grading of embryos does not tell us the full story so it can be moot when we have the best-graded embryos failing to implant and lead to live births!
“When it comes to grading, we don’t wing it. We have protocols, cross-checks, and backup embryologists standing by—because this isn’t brunch, it’s your future baby we’re plating.”
