As screening colonoscopy becomes more widespread, the costs for histopathological assessment of resected polyps are rising correspondingly.
Reference centres have published highly accurate results for endoscopic polyp classification.
Therefore, it has been proposed that, for smaller polyps, the differential diagnosis that guides follow-up recommendations could be based on endoscopy alone.
Professor Thomas Rösch and colleagues from Germany prospectively assessed whether the high accuracy for endoscopic polyp diagnosis as reported by reference centres can be reproduced in routine screening colonoscopy.
The research team reported that 10 experienced private practice endoscopists had initial training in pit patterns.
Then they assessed all polyps detected during 1069 screening colonoscopies.
Patients were randomly assigned to colonoscopy with conventional or latest generation HDTV instruments.
|Image-based recommendations for post-polypectomy surveillance were correct in only 70% of cases|
The team's main outcome measure was diagnostic accuracy of in vivo polyp assessment.
Secondary outcome measures were differences between endoscopes and reliability of image-based follow-up recommendations.
The researchers also performed a blinded post hoc analysis of polyp photographs.
The research team assessed 675 polyps.
Accuracy, sensitivity and specificity of in vivo diagnoses were 77%, 78% and 73%.
Size of adenomas and endoscope withdrawal time significantly influenced accuracy.
The researchers noted that image-based recommendations for post-polypectomy surveillance were correct in only 70% of cases.
Post hoc analysis of polyp photographs did not improve accuracy.
Professor Rösch's team concludes, "In everyday practice, endoscopic classification of polyp type is not accurate enough to abandon histopathological assessment, and use of latest generation colonoscopes does not improve this."
"Image-based surveillance recommendations after polypectomy would consequently not meet guideline requirements."