Excellent Bowel Preparation Improves Detection of Serrated Polyps During FIT-Based Colonoscopy: GIE | July 2026

Introduction:

Serrated polyps, particularly proximal sessile serrated lesions (SSLs), are increasingly recognised as major precursors of post-colonoscopy colorectal cancer (PCCRC). This study evaluated whether achieving excellent bowel preparation (Boston Bowel Preparation Scale [BBPS] 8–9) provides additional benefits over good preparation (BBPS 6–7) for detecting serrated lesions in FIT-positive screening colonoscopies.

Why was this study needed?

• Serrated lesions are subtle, flat, and easily missed during colonoscopy.
• Approximately one-third of colorectal cancers arise through the serrated pathway.
• Current quality indicators focus mainly on adenoma detection rate (ADR).
• The impact of bowel preparation quality on serrated lesion detection has been unclear.
• Improving serrated lesion detection may reduce interval colorectal cancers.

Results:

• Excellent bowel preparation significantly improved proximal serrated polyp detection rate (PSDR) and sessile serrated lesion detection rate (SSLDR) compared with good bowel preparation.
• A stepwise improvement was observed with increasing bowel cleanliness, with BBPS 9 outperforming BBPS 8, emphasizing that "excellent" preparation provides additional benefit beyond simply "good."
• No significant improvement was observed in adenoma detection rate (ADR) or adenomas per colonoscopy (APC), indicating that the benefit of superior bowel preparation is specific to serrated pathway lesions.

Clinical Impact:

This study suggests that endoscopy units should aim for excellent bowel preparation rather than merely adequate preparation, particularly in FIT-positive screening programs. In addition to adenoma detection rate (ADR), quality monitoring should incorporate proximal serrated polyp detection rate (PSDR) and sessile serrated lesion detection rate (SSLDR) as complementary quality indicators to reduce interval colorectal cancer.

Bottom Line:

Excellent bowel preparation (BBPS 8–9) significantly enhances detection of proximal serrated polyps and sessile serrated lesions but does not increase adenoma detection. Achieving excellent, rather than simply good, bowel cleansing may be a key strategy for reducing post-colonoscopy colorectal cancer through improved detection of serrated pathway lesions.