The reproducibility of the revised American Fertility Society classification of endometriosis

Abstract

Objective: To assess the degree of intraobserver and interobserver variability in endometriosis staging using the revised American Fertility Society (AFS) classification of endometriosis.

Design: Videotapes of laparoscopies of 20 patients with endometriosis were each scored twice by five observers.

Setting: The reproductive endocrine unit of a tertiary care, university-affiliated hospital.

Subjects: Five subspecialty-certified reproductive endocrinologists.

Interventions: None.

Main outcome measures: Variability in assigned score was measured for each of the five components of the AFS classification, as well as total scores and stage of endometriosis.

Results: There was considerable variability in the scores assigned to each videotape, both by the same observer and by different observers. The grand total score, which ranged from 0 to 90, varied with an SD of 13.44 when a single patient was rated twice by the same observer and varied with an SD of 17.12 when a single patient was rated by two different observers. Among individual components of the score, the greatest variability occurred in endometriosis of the ovary and cul-de-sac obliteration, with less variability observed for peritoneum endometriosis and for ovarian and tubal adhesions. Comparison of intraobserver and interobserver scores resulted in a change in endometriosis stage in 38% and 52% of patients, respectively. There were statistically significant differences in mean endometriosis scores among the observers in four of the five anatomic categories examined.

Conclusions: Intraobserver and interobserver variability was high for ovarian endometriosis and cul-de-sac subscores using the revised AFS classification of endometriosis.