Bowel preparation quality scales for colonoscopy

Table 1 Validated bowel preparation scales

Scale name	Score	Rating/description	Other scale properties/characteristics
Aronchick Scale	1	Excellent: Small volume of liquid; > 95% of mucosa seen	Total score range: Minimum 1 (excellent) to maximum 5 (inadequate) Scoring performed before washing or suctioning No separate ratings for segments; global colon rating only No threshold for adequate/inadequate provided
	2	Good: Clear liquid covering 5%-25% of mucosa, but > 90% of mucosa seen
	3	Fair: Semisolid stool could not be suctioned or washed away, but > 90% of mucosa seen
	4	Poor: Semisolid stool could not be suctioned or washed away and < 90% of mucosa seen
	5	Inadequate: Repeat preparation/screening needed
Ottawa Bowel Preparation Scale (by colon segment)	0	Excellent: Mucosal detail clearly visible, almost no stool residue; if fluid present, it is clear, almost no stool residue	Total score (obtained by adding scores for each segment + total colon fluid score) range: Minimum 0 (excellent) to maximum 14 (inadequate) Scoring performed before washing or suctioning Rates cleansing by colon segment: Right colon, mid-colon, and rectosigmoid colon (Figure 1) No threshold for adequate/inadequate provided
	1	Good: Some turbid fluid or stool residue, but mucosal detail still visible without need for washing/suctioning
	2	Fair: Some turbid fluid of stool residue obscuring mucosal detail; however, mucosal detail becomes visible with suctioning, washing not needed
	3	Poor: Stool present obscuring mucosal detail and contour; a reasonable view is obtained with suctioning and washing
	4	Inadequate: Solid stool obscuring mucosal detail and not cleared with washing and suctioning
Ottawa Bowel Preparation Scale (total colon fluid)	0	Small amount of fluid	Total colon fluid score range: Minimum 0 (small amount of fluid) to maximum 2 (large amount of fluid) Scoring performed before washing or suctioning Single score for the total colon No threshold for adequate/inadequate provided
	1	Moderate amount of fluid
	2	Large amount of fluid
Boston Bowel Preparation Scale (by colon segment)	0	Unprepared colon segment with mucosa not seen because of solid stool that cannot be cleared	Total score (obtained by adding scores for each segment) range: Minimum 0 (very poor) to maximum 9 (excellent) Scoring performed after washing or suctioning Segments separately rated: Right colon (including cecum and ascending colon); transverse (includes hepatic and splenic flexures); and left colon (descending and sigmoid colon, and rectum) Threshold optimally is total score of ≥ 6 AND ≥ 2 per segment
	1	Portion of mucosa of the colon segment seen, but other areas of segment not well seen because of staining, residual stool, and/or opaque liquid
	2	Minor amount of residual staining, small fragments of stool, and/or opaque liquid, but mucosa of colon segment is well seen
	3	Entire mucosa of colon segment well seen, with no residual staining, small fragments of stool, or opaque liquid
Harefield Cleansing Scale (by colon segment)	0	Irremovable, heavy, hard stools	Total score (obtained by adding scores for each segment) range: Minimum 0 (very bad) to maximum 20 (very good) Scoring performed after washing or suctioning Segments separately rated: Rectum, sigmoid, left, transverse, right colon Threshold for successful cleansing = Grade A: no segment scored < 3 or 4, or Grade B: ≥ 1 segment scored 2 but no segment < 2; Unsuccessful cleansing = Grade C: ≥ 1 segment scored 1 but no segment < 1, or Grade D: ≥ 1 segment scored 0
	1	Semisolid, only partially removable stools
	2	Brown liquid/fully removable semi-solid stools
	3	Clear liquid
	4	Empty and clean
Chicago Bowel Preparation Scale (by colon segment)	0	Unprepared colon segment with stool that cannot be cleared (> 15% of mucosa not seen)	Total score (obtained by adding scores for each segment) range: Minimum 0 (unprepared) to maximum 36 (excellent) Scoring performed before (fluid) and after (mucosal cleaning) washing or suctioning Segments separately rated: Right (cecum to mid-hepatic flexure), transverse (mid-hepatic flexure to mid-splenic flexure), and left colon (mid-splenic flexure to distal rectum) No threshold for adequate/inadequate provided
	5	Portion of mucosa in segment seen after cleaning, but up to 15% of the mucosa not seen because of retained material
	10	Minor residual material after cleaning, but mucosa of segment generally well seen
	11	Entire mucosa of segment well seen after washing
	12	Entire mucosa of segment well seen before washing or suctioning
Chicago Bowel Preparation Scale (total colon)	0	Little fluid (≤ 50 cc)	Total score range: Minimum 0 (little fluid) to maximum 3 (large amount of fluid) Scoring performed before washing or suctioning No threshold for adequate/inadequate provided Not incorporated into total score for segments
	1	Minimal amount of fluid (51-150 cc)
	2	Moderate amount of fluid (151-300 cc)
	3	Large amount of fluid (> 300 cc)

Table 2 Reliability and validation data for bowel preparation scales

Scale	Study	Colons (n)	Raters (n)	Reliability	Validity
Aronchick	Aronchick[41], 2004	80	5	ICC values for: Total colon: 0.77 Cecum: 0.76 Distal colon: 0.31	NR
OBPS	Rostom et al[50], 2004	97	2	ICC values for: Right colon: 0.92 Mid colon: 0.88 Rectosigmoid colon: 0.89	Comparisons with Aronchick scale PCC: 0.89 OBPS vs 0.62 Aronchick ICC: 0.94 OBPS vs 0.77 Aronchick
	Chan et al[53], 2011	211	NR	NR	Cutoff scores for adequacy/inadequacy Optimal cutoff for inadequate ≥ 8: Sensitivity, 100%, specificity, 91%
	Martinato et al[54], 2013	150	NR	Ratings of physicians vs nurses: PCC: r = 0.60	Correlations with VAS PCC (physicians vs nurses): r = 0.60
	Lee et al[58], 2016	655	NA	NR	Comparison with BBPS for PDR and ADR PCC: r = -0.62 (P < 0.001); AUC of ROC analysis similar for PDR, ADR, right-sided adenomas, and SSAs
BBPS	Lai et al[47], 2009	633	22	ICC values: 0.74/0.77 wtd κ	PDR by score 40% for scores ≥ 5 vs 24% for scores < 5 (P < 0.02) Need for repeat CSP due to inadequate bowel prep 2% for scores ≥ 5 vs 73% for scores < 5 (P < 0.001) Correlation with colonoscope insertion time PCC: r = -0.16 (P < 0.003) Correlation with colonoscope withdrawal time PCC: r = -0.23 (P < 0.001)
	Calderwood et al[43], 2010	119	12	ICC values for: Total colon: 0.91 Right colon: 0.88 Transverse colon: 0.83 Left colon: 0.79	Correlations with ability to exclude polyps > 5 mm 100%, 88%, 82%, 33%, and 0% of physicians deemed bowel preparation adequate to exclude polyps > 5 mm at scores of ≥ 8, 7, 6, 5, and ≤ 4 respectively Correlations with surveillance recommendations after normal CSP Score < 5: 100% recommended ≤ 1 yr Scores 5-6: mean recommended interval 4.3 (± 3.9) yr Scores ≥ 7: 100% recommended 10 yr
	Calderwood et al[44], 2014	2516	74	NR	Physician-recommended CSP interval after negative CSP Scores ≥ 6 (≥ 2 each segment): 90% recommended 10 yr Scores 0-2: 96% recommended ≤ 1 yr
	Schindler et al[49], 2016	3	401	ICC values, all raters (all segment and total scores): 0.93	NR
	Gao et al[45], 2013	1012	13	ICC values: 0.987/0.671 wtd κ	PDR Scores ≥ 5 superior vs < 5 (35% vs 18%; P < 0.05)
	Kim et al[46], 2014	482	6	ICC values: Total colon: 0.90/0.63 wtd κ Right colon: 0.93/0.91 wtd κ Transverse colon: 0.88/0.86 wtd κ Left colon: 0.50/0.38 wtd κ	PDR Scores ≥ 8 superior vs scores < 8 (44.9% vs 33.0%; P = 0.04) Colonoscope withdrawal time PCC: r = -0.167 (P < 0.001) Colonoscope insertion time PCC: r = 0.018 (P = 0.695)
	Clark et al[57], 2016	438	4	ICC values by BBPS scores: 0 and 3: 1.0 2: 0.81 1: 0.80	ADR (> 5 mm) miss rates by BBPS score: 3: 5.6% 2: 5.2% 1: 15.9% Score of 2 noninferior to 3 for missed adenoma > 5 mm
HCS	Halphen et al[51], 2013	337	4	ICC value: 0.457 Test-retest κ values: Range, 0.33 to 0.85 Intrarater2: 0.28 to 0.64 Internal consistency3: 0.81, 0.86	Best score cutoff for satisfactory bowel preparation ≥ 2 for each segment: Sensitivity, 99% and specificity, 83% Correlation with Aronchick scale PCC: r = 0.833 AUC of ROC analysis (vs Aronchick scale scores) 0.945 for total colon
CBPS	Gerard et al[52], 2013	150	44	ICC values for: Range, 0.624 to 0.702 for all segments	Correlations of scores with adequate cleansing Adequate: Scores of 25-36 (≥ 95% of mucosa visualized) Inadequate: Scores of 0-24 (< 95% of mucosa visualized)

¹Raters included endoscopy nurses (n = 17), gastroenterology faculty (n = 14), and gastroenterology fellows (n = 9);

²Generalized κ for global agreement;

³Cronbach’s alpha;

⁴Raters included three gastroenterologists and one physician’s assistant. ADR: Adenoma detection rate; AUC: Area under the curve; BBPS: Boston Bowel Preparation Scale; CBPS: Chicago Bowel Preparation Scale; CSP: Colonoscopy; HCS: Harefield Cleansing Scale; ICC: Interobserver reliability kappa intraclass correlation coefficient; NA: Not applicable; NR: Not reported; OBPS: Ottawa Bowel Preparation Scale; PCC: Pearson correlation coefficient; PDR: Polyp detection rate; ROC: Receiver operating characteristic; SSA: Sessile serrated adenoma; VAS: Visual analogue scale; wtd: Weighted.