Boston Bowel Preparation Scale (BBPS) Calculator
Score colonoscopy bowel preparation with the Boston Bowel Preparation Scale — right, transverse and left colon each 0–3 after washing — for a 0–9 total and adequate or inadequate preparation.
How it works
BBPS = right colon (0–3) + transverse colon (0–3) + left colon (0–3), each scored after cleaning (washing and suction); total 0–9. Adequate preparation: total ≥ 6 with every segment ≥ 2.
The Boston Bowel Preparation Scale (Lai et al., Gastrointestinal Endoscopy 2009) is the most validated scale for rating colonoscopy cleanliness. Each segment is scored after the endoscopist has washed and suctioned, so it reflects how well the mucosa could be seen for polyp detection. A total of 6 or more with every segment scoring at least 2 is linked to adequate polyp detection and allows standard surveillance intervals (Calderwood 2014); inadequate preparation usually means repeating the colonoscopy within a year.
Worked example
The right colon is spotless (3) and the transverse and left colon have minor staining but the mucosa is well seen (2 each): BBPS = 3 + 2 + 2 = 7 / 9 — adequate preparation (total ≥ 6 and every segment ≥ 2).
Sources: Lai EJ et al. The Boston Bowel Preparation Scale: a valid and reliable instrument for colonoscopy-oriented research. Gastrointest Endosc 2009 · Calderwood AH et al. Boston Bowel Preparation Scale scores provide a standardized definition of adequate for describing bowel cleanliness. Gastrointest Endosc 2014
Frequently asked questions
What is a good Boston Bowel Preparation score?
A total of 6 or more out of 9 with no segment below 2 is adequate. A perfect score is 9 (3 in every segment).
Is the BBPS scored before or after washing?
After. Each segment is scored once the endoscopist has finished washing and suctioning, reflecting what could actually be seen.
What happens if the prep is inadequate?
Small polyps may have been missed, so guidelines usually advise repeating the colonoscopy within one year, often with a stronger or split-dose preparation.
Can a total of 6 still be inadequate?
Yes — for example 3 + 3 + 0 adds to 6, but a segment scoring 0 or 1 makes the preparation inadequate for that segment.
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Clinical decision tool for education and for use by trained clinicians alongside clinical judgement — not a diagnosis and not a substitute for medical assessment. Scores validated in specific populations may not apply to every patient.