What is the American Fertility Society (AFS) grade?

American Fertility Society (AFS) Grade for Endometriosis

The American Fertility Society (AFS) grade is a scoring system designed for classifying endometriosis in the small pelvis, which evaluates adhesions at four specific sites: right ovary, right tube, left ovary, and left tube, with the final score based on the side with the lowest summed score.

Classification System Details

The AFS grading system (later renamed the American Society for Reproductive Medicine's classification) has been widely used since 1985 to categorize the extent and severity of endometriosis 1. The system works as follows:

• Evaluation sites: Right ovary, right tube, left ovary, and left tube
• Scoring method: Points are assigned based on the extent and severity of adhesions at each site
• Final score calculation: The scores for right and left sides are summed separately, and the final AFS score is determined by the side with the lowest summed score (while discarding the score for the other side) 1

Staging Categories

The AFS system classifies endometriosis into four stages:

• Stage I: Minimal endometriosis
• Stage II: Mild endometriosis
• Stage III: Moderate endometriosis
• Stage IV: Severe endometriosis

Limitations of the AFS Grading System

The AFS grading system has several important limitations that clinicians should be aware of:

1. Incomplete patient assessment: A patient with an AFS score of 0 can still have endometriosis in other locations 1

2. Low inter-observer reproducibility: The system has relatively poor consistency between different evaluators 1

3. Poor correlation with symptoms: The classification does not correlate well with underlying symptoms, creating challenges in diagnosis and treatment selection 2

4. Limited predictive value: The system has inadequate predictive value for important clinical outcomes:

   • No significant association with post-surgical pregnancy rates (47% overall at 3 years, with similar rates across all stages) 3
   • Limited correlation with pain recurrence 3
   • Only partial correlation with disease relapse (significantly higher in stage IV) 3

5. Inadequate for deep infiltrating endometriosis: The system does not account for deep infiltrating endometriosis, which led to the development of supplementary classification systems like the ENZIAN score 4

Evolution and Modifications

Due to these limitations, the AFS/ASRM classification has undergone modifications:

• A modified AFS system has gained popularity in more recent studies 1
• The ASRM has proposed adding color photographs to improve consistency in describing endometriosis appearance 5
• Changes in assessing cul-de-sac obliteration have been suggested to reduce observer variations 5

Alternative Classification Systems

For more comprehensive endometriosis assessment, other systems have been developed:

• ENZIAN score: Supplements the AFS score by describing deep infiltrating endometriosis, retroperitoneal structures, and involvement of other organs 4
• Peritoneal Adhesion Index (PAI): A more recent system that measures adhesion tenacity on a 1-3 scale at 10 predefined sites, integrating both tenacity and extent of adhesions 1

Clinical Implications

When using the AFS grading system in clinical practice:

• Recognize that the stage may not correlate with symptom severity or fertility outcomes
• Consider supplementary classification systems for deep infiltrating endometriosis
• Understand that the system primarily focuses on anatomical distribution rather than functional impact
• Be aware that the classification alone is insufficient for predicting treatment response or prognosis

The AFS grading system, while widely used, should be considered just one component of a comprehensive evaluation of patients with endometriosis, with its limitations clearly understood when making clinical decisions.