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Patients with longstanding ulcerative colitis (UC) are at increased risk of developing colorectal neoplasia. Chromoendoscopy (CE) increases detection of lesions, and Kudo pit pattern classification I and II have been suggested to be predictive of benign polyps in UC. Little is known on the use of this classification in non-magnified high-definition (HD) (virtual) CE and narrow-band Imaging (NBI), or on the interobserver agreement. The aim of this pilot study was to assess the diagnostic accuracy and the interobserver agreement of the Kudo pit pattern classification in UC patients undergoing surveillance with methylene blue CE or NBI in a multicenter study.Fifty images of lesions identified in 27 UC patients (13 neoplastic) either with classical CE (methylene blue 0.1%) (n=24) or NBI (n=26), were selected by an independent investigator. Images were selected from a randomized controlled trial to compare CE and NBI. All nonmagnified images were obtained with an Exera II Olympus processor and were mounted in a PowerPoint file in a standardized way (same size; black background). Ten endoscopists with extensive experience in NBI/CE were asked to assess the lesions for the predominant Kudo pit pattern (I, II, IIIL, IIIS, IV and V), to indicate if they thought the lesion was neoplastic and how confident they were about the diagnosis. Histology was used as the criterion standard.Median sensitivity, specificity, negative predictive value, and positive predictive value for diagnosing neoplasia based on the presence of pit pattern other than I or II was 77%, 68%, 88%, and 46%, respectively. Diagnostic accuracy was significantly higher when a diagnosis was made with a high level of confidence (77% vs 21%, p < 0.001). The overall inter-observer agreement for any pit pattern was only fair (κ = 0.282), with CE being significantly better than NBI (0.322 vs 0.224, p < 0.001). From a clinical viewpoint, the difference between neoplastic and non-neoplastic lesions is important. The agreement for differentiation between non-neoplastic patterns (I, II) and neoplastic patterns (IIIL, IIIS, IV, or V) was moderate (κ 0.587) and even significantly better for NBI in comparison with CE (κ 0.653 vs 0.495, p < 0.001).Differentiation between non-neoplastic and neoplastic pit patterns in UC lesions shows a moderate to substantial agreement among expert endoscopists. The agreement for differentiating neoplastic from non-neoplastic lesions is significantly better for NBI in comparison with HDCE. The assessment of pit pattern I or II with non-magnified HD-CE or NBI has a high negative predictive value to rule out neoplasia.

Original publication




Journal article


Gastrointestinal endoscopy

Publication Date



Department of Gastroenterology and hepatology, Department of Gastroenterology and hepatology, University Hospital Leuven, KU Leuven, Belgium. Electronic address: