The Hidden Cost of Missed Polyps

Colorectal cancer is the second leading cause of cancer death in the United States, yet it is one of the most preventable cancers when detected at the precancerous polyp stage. Colonoscopy is the gold standard screening tool: a gastroenterologist inserts a camera-equipped scope, visually inspects the colon lining, and removes any suspicious growths before they can become cancerous. The problem is that human visual inspection, even by experienced endoscopists, misses a meaningful fraction of adenomas—precancerous polyps—during a standard colonoscopy procedure. AI-assisted detection systems are now beginning to close that gap.

What Gets Missed and Why

Not all polyps are equally detectable. Pedunculated polyps—the mushroom-shaped growths on stalks—are relatively easy to spot. The harder targets are flat or sessile serrated adenomas that hug the colonic mucosa and can blend with normal tissue folds. These lesions are disproportionately dangerous: sessile serrated lesions follow a faster malignant progression pathway than conventional adenomas and are more likely to develop into the aggressive microsatellite-instable colorectal cancers that are hardest to treat.

Endoscopist fatigue is a genuine factor. A colonoscopy procedure requires sustained visual attention while managing scope mechanics, patient communication, and documentation—a multitasking load that degrades detection performance over the course of a procedure and a clinical day. Back-to-back colonoscopy studies, where a second endoscopist immediately re-examines the colon, find adenoma miss rates of 20-26%, with flat lesions overrepresented among the missed adenomas.