Aims
High-quality bowel preparation is crucial for a successful colonoscopy, as well as for effective colorectal cancer prevention(1). Simethicone, an anti-foaming agent, reduces intraluminal bubbles and improves mucosal assessment(2). Its potential benefits when added to very–low-volume polyethylene glycol + ascorbic acid (PEG-AC) preparations have not been evaluated in real-world practice. The aim of the study is to assess whether adding simethicone to very–low-volume 1 litre PEG-AC bowel preparation reduces bubble formation, improves bowel cleanliness, and affects patient experience compared to PEG-AC alone.
Methods
This ongoing multicenter project, involving seven endoscopy units across Sweden, started in September 2024. Consecutive outpatients undergoing a complete colonoscopy were assigned to standard PEG-AC (control) or PEG-AC plus simethicone (3 × 200 mg capsules per dose). Bowel cleanliness was assessed using the Boston Bowel Preparation Scale (BBPS)(3), and the presence of bubbles was assessed during intubation using the Colon Endoscopic Bubble Scale (CEBuS)(4). Patient experience of bowel preparation and procedural data were collected. Data were analyzed using descriptive statistics, t-tests or Mann–Whitney U tests for continuous variables, and χ² tests for categorical variables.
Results
A total of 637 patients were included (PEG-AC: n = 407; PEG-AC + simethicone: n = 230). Mean age was similar (59.8 vs. 60.2 years), but with more females in the simethicone group (p=0.010). CEBuS scores were significantly lower in the simethicone arm in all bowel segments (p<0.0001), and associated with a tenfold increased use of simethicone in the PEG-AC group - 31.1% compared to only 3,9% in the simethicone group (p<0.001).However, there were no significant differences between the groups in total or segmental BBPS, including high-quality cleansing (total BBPS 8–9 or right-sided score 3) after adjusting for age, sex, preparation volume, water use during intubation, and extra intraprocedural simethicone use. Procedure and withdrawal time, polyp detection rates and patient-reported symptoms (bloating, nausea, vomiting) were also similar after adjusting as before mentioned. The descriptive statistics are depicted in Table 1.
|
Parameter |
PEG-AC arm |
PEG-AC + simethicone arm |
χ ² and p value |
|
|
Age in years (mean (range)) |
59.81 (19-91) |
60.29 (20-88) |
ns |
|
|
Sex (% women) |
45.8% |
57.8% |
χ²=6.616 p=0.010 |
|
|
CEBuS (mean (SD)) |
CEBuS Left colon |
0.50 (0.68) |
0.14 (0.39) |
p<0.0001 |
|
CEBuS Transverse colon |
0.50 (0.72) |
0.12 (0.37) |
p<0.0001 |
|
|
CEBuS Right colon |
0.60 (0.74) |
0.09 (0.32) |
p<0.0001 |
|
|
CEBuS Total |
1.59 (1.72) |
0.34 (0.94) |
p<0.0001 |
|
|
BBPS (mean (SD)) |
BBPS Right colon |
2.56 (0.54) |
2.62 (0.50) |
ns |
|
BBPS Transverse colon |
2.83 (0.38) |
2.78 (0.45) |
ns |
|
|
BBPS Left colon |
2.63 (0.50) |
2.67 (0.50) |
ns |
|
|
BBPS Total |
8.0 (1.22) |
8.07 (1.27) |
ns |
|
|
BBPS Right High (%) |
58.1% |
63.0% |
ns |
|
|
BBPS Total High (%) |
65.9% |
70.0% |
ns |
|
|
Intra-procedural simethicone (% used) |
31.1% |
3.9% |
χ²=64.816 p<0.001 |
|
|
Procedure time in min (mean (SD)) |
34.40 (14.55) |
31.07 (15.75) |
ns |
|
|
Withdrawal time in min (mean (SD)) |
19.12 (11.01) |
16.96 (11.41) |
ns |
|
PEG-AC, BBPS, CEBuS - see text; BBPS Right High BBPS in the right colon =3; BBPS Total High BBPS total score >7; min minutes; SD standard deviation; ns non-significant
Conclusions
The addition of simethicone to very–low-volume PEG + ascorbic acid effectively reduced bubbles in the large bowel, though no improvements were observed in cleanliness, polyp detection, procedure times or patient experience in this interim analysis.