Directional Bias in Polyp Detection during Colonoscopy: A Prospective Observational Study.

Area of Science:

• Gastroenterology
• Endoscopy
• Colorectal Cancer Prevention

Background:

• Colonoscopy is crucial for colorectal cancer prevention, but missed lesions lead to interval cancers.
• Adjunctive technologies can improve adenoma detection, but inherent visibility differences are less understood.

Purpose of the Study:

• To evaluate if polyp detection during colonoscopy withdrawal varies by the short-axis direction of the colonic lumen (SADCO).

Main Methods:

• Prospective observational study using the short-axis directional classification (SADCO) to record lesion visualization direction.
• Primary outcome: lesion detection distribution between upper-left (ULD) and lower-right (LRD) directions.
• Subgroup analyses, logistic regression, and quadrant analysis were performed.

Main Results:

• 1,185 lesions from 432 patients analyzed; ULD detection was significantly lower than LRD (42.4% vs. 57.6%).
• This pattern persisted across lesion characteristics and endoscopist experience.
• Advanced neoplasia detection was significantly reduced in the ULD (40.7% vs. 59.3%).

Conclusions:

• Colonoscopic polyp detection exhibits a consistent directional bias, with reduced detection in the ULD.
• Awareness of this limitation and targeted ULD inspection can optimize colonoscopy effectiveness.