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Boston Bowel Preparation Scale (BBPS)

The Boston Bowel Preparation Scale scores right, transverse and left colon cleanliness 0–3 each after washing and suctioning (total 0–9). Preparation is adequate for standard surveillance intervals when every segment scores ≥2 (total ≥6); a total ≤2 warrants repeat colonoscopy within a year.

  • Right colon segment: 0: Unprepared, solid stool that cannot be cleared; 1: Portion of mucosa seen; other areas obscured; 2: Minor residual staining or small fragments; mucosa well seen; 3: Entire mucosa well seen
  • Transverse colon segment: 0: Unprepared, solid stool that cannot be cleared; 1: Portion of mucosa seen; other areas obscured; 2: Minor residual staining or small fragments; mucosa well seen; 3: Entire mucosa well seen
  • Left colon segment: 0: Unprepared, solid stool that cannot be cleared; 1: Portion of mucosa seen; other areas obscured; 2: Minor residual staining or small fragments; mucosa well seen; 3: Entire mucosa well seen
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Interpretation

ResultMeaning
All segments ≥2Adequate; routine interval
Any segment <2Inadequate; repeat sooner
Total ≤2Repeat within 1 year

Formula

Each segment (right incl. cecum/ascending; transverse incl. flexures; left incl. descending/sigmoid/rectum): 0 = unprepared, solid stool cannot be cleared; 1 = portion of mucosa seen, other areas obscured; 2 = minor residual staining/small fragments, mucosa well seen; 3 = entire mucosa well seen. Total = sum (0–9).

Clinical pearls

  • Score after all washing and suctioning are complete (the withdrawal view).
  • A segment not reached because of poor prep is scored 0.

Examples

bbps 3 3 2Boston bowel prep: right colon 1, transverse 2, left 3bowel prep score right 0 transverse 1 left 1

FAQ

What BBPS score is adequate?

A score of at least 2 in every segment (total ≥6) is adequate for routine follow-up intervals.

Is BBPS 6 always adequate?

No. A total of 6 made up as 3-3-0 is inadequate, because one segment scores below 2.

Evidence

  1. Lai EJ et al. The Boston bowel preparation scale: a valid and reliable instrument for colonoscopy-oriented research. Gastrointest Endosc 2009;69:620–5.
  2. Calderwood AH et al. Boston Bowel Preparation Scale scores provide a standardized definition of adequate for describing bowel cleanliness. Gastrointest Endosc 2014;80:269–76.

Hepatology & GI · Reviewed 2026-10-14 · Methodology