Classification Criteria for Advanced Adenomas of the Colon by Using Probe-Based Confocal Laser Endomicroscopy: A Preliminary Study

BACKGROUND: Probe-based confocal laser endomicroscopy may allow a strategy of diagnose, resect, and discard for small nonadvanced adenomas, but there are concerns about discarding polyps with advanced histology. OBJECTIVE: The aim of this study was to evaluate the potential use of probe-based confocal laser endomicroscopy to aid in distinguishing low-grade from advanced colon adenomas. DESIGN: Six observers, blinded to histopathology, scored 5 adenoma features and an overall diagnosis and confidence level for the diagnosis. SETTING: This study was conducted at single, tertiary care referral center. PATIENTS: Patients undergoing screening and surveillance colonoscopies and for whom an adenomatous polyp was removed were included. INTERVENTIONS: A sample of 27 advanced adenomas and 120 nonadvanced adenomas were used in the study. An initial classification system was created with 10 advanced and 10 nonadvanced adenomas. The remaining 127 adenomas were scored by each observer in the validation portion of the study. MAIN OUTCOME MEASURES: The primary outcome measured was the accurate classification of advanced and nonadvanced adenomas. RESULTS: Overall, across all 6 observers, the sensitivity in correctly classifying advanced adenomas was 43%, the negative predictive value was 89%, the specificity was 71%, and the positive predictive value was 19%. No single feature or combination of features as seen with probe-based confocal laser endomicroscopy consistently identified advanced adenomas. LIMITATIONS: Classification criteria were developed subjectively, and there was limited observer experience with probe-based confocal laser endomicroscopy use. CONCLUSIONS: Our initial attempt at creating classification criteria for probe-based confocal laser endomicroscopy did not consistently distinguish advanced from nonadvanced adenomas and, therefore, is not useful in applying a diagnose, resect, and discard strategy. However, further refinement of our probe-based confocal laser endomicroscopy classification scheme in future studies has potential to accurately detect advanced histology in colorectal polyps.