BBPS stands for the Boston Bowel Preparation Scale, a scoring system doctors use during a colonoscopy to rate how clean your colon was before the procedure. The scale runs from 0 to 9, with higher scores meaning your bowel prep did a better job clearing things out. If you’re seeing this term on a colonoscopy report, it’s telling you (and your doctor) whether the view inside your colon was clear enough to trust the results.
How the Scale Works
The BBPS divides your colon into three segments: the right side, the middle (transverse), and the left side. Each segment gets a score from 0 to 3, and the three scores are added together for a total between 0 and 9.
Here’s what each segment score means:
- 0: The colon lining can’t be seen at all because solid stool is in the way.
- 1: Parts of the lining are visible, but other areas are blocked by residual stool or opaque liquid.
- 2: The lining is mostly visible, with only small amounts of residual material remaining.
- 3: The entire lining of that segment is clearly visible with no residual staining or stool.
Scoring happens during the withdrawal phase of the colonoscopy, after the doctor has already flushed and suctioned the colon. This is an important detail: the score reflects how well the prep worked even after the doctor has done everything possible to clean things up during the procedure itself.
What Counts as an Adequate Score
A preparation is considered adequate when each of the three colon segments scores at least a 2. That means the total score needs to be at least 6, but more importantly, no single segment can fall below 2. A total of 6 where one segment scored a 1 wouldn’t meet the threshold, even though the number looks the same. Research published in Gastroenterology found that scores of 2 or 3 across all segments provide reliable detection of polyps larger than 5 millimeters, which is the size range that matters most for cancer prevention.
In practice, most colonoscopy reports will note whether the preparation was “adequate” or “inadequate” alongside the BBPS number, so you don’t necessarily need to do the math yourself.
Why Your Score Matters
The whole point of a colonoscopy is finding and removing polyps before they can develop into colon cancer. If residual stool is hiding parts of your colon lining, polyps can be missed. That’s the core concern with a low BBPS score.
The relationship between prep quality and polyp detection is nuanced, though. One large study found that overall detection rates for polyps and precancerous growths (adenomas) were similar across prep quality levels: about 37% of patients with poor prep had adenomas found, compared to 35% with adequate prep and 33% with excellent prep. Those numbers seem counterintuitive, but there’s a catch. Among patients who did have adenomas, those with poorer prep tended to have larger ones detected. This suggests that poor prep doesn’t prevent doctors from spotting big, obvious growths, but it likely hides smaller ones. The effect was strongest in the right colon, which is the hardest segment to clean and also where some of the most concerning flat polyps tend to develop.
When a segment scores inadequately on the BBPS, the risk of finding polyps on a follow-up colonoscopy roughly doubles. One study found that segments with inadequate scores had a 10% polyp detection rate on a repeat procedure, compared to 5% for segments that were adequately prepped the first time. For advanced polyps, the gap was even wider: 20% versus 4% in segments where polyps had already been found.
What Happens After a Low Score
If your BBPS score falls below the adequate threshold, your doctor will typically recommend a repeat colonoscopy sooner than the usual screening interval. Instead of waiting 10 years (or whatever your normal schedule would be), you might be asked to come back within one year. The reasoning is straightforward: if parts of your colon couldn’t be properly examined, the screening wasn’t complete.
This creates a real cost in terms of time, expense, and the inconvenience of going through another bowel prep. Inadequate preparation is considered a priority quality indicator in colonoscopy for exactly this reason. It’s one of the most common causes of repeat procedures that could have been avoided.
How to Improve Your Prep Score
Since the BBPS reflects how well you prepped, the factors that influence it are largely within your control. The most common reasons for low scores are not finishing the entire prep solution, not following the clear-liquid diet in the days before, and poor timing of when you drink the prep relative to your procedure.
Split-dose prep, where you drink half the solution the evening before and half the morning of your colonoscopy, consistently produces better BBPS scores than drinking everything the night before. The closer the second dose is to your procedure time, the cleaner your colon tends to be. If your procedure is scheduled for the afternoon, ask your doctor about adjusting the timing of your prep doses accordingly.
Staying well-hydrated with clear fluids throughout the prep process also helps. Foods with small seeds, nuts, or high fiber should be avoided for a few days beforehand, as these leave residue that the prep solution has difficulty clearing. If you’ve had an inadequate prep in the past, let your doctor know, since they may prescribe a higher-volume solution or add extra steps to the prep regimen for your next procedure.