Colon Cleaning after Inadequate Bowel Preparation: A Pooled-data Analysis

Clinical Snapshot

Key Findings

• P Value: Not reported

• Effect Size: Overall pooled success rate: 79.3%; by subgroup — high-volume PEG: 78.1%, low-volume PEG: 75.3%, oral sennosides: 82.5%, colonoscope/device-assisted: 84.6%

• Primary Outcome: Success rate of achieving adequate colon cleansing following rescue bowel preparation strategy

• Nnt Or Sensitivity: Approximately 1 in 5 patients (approximately 20%) fails to achieve adequate cleansing even with rescue strategies; NNT not calculable from available data

• Confidence Interval: Overall 95% CI: 77.5–80.1% (note: asymmetric and methodologically unexplained)

Clinical Application

Oral rescue strategies (PEG, sennosides) are generally feasible in outpatient and day-procedure settings with minimal additional infrastructure. Device-assisted preparation (e.g., colonoscope-assisted water exchange, cap-assisted techniques) requires endoscopic expertise and may increase procedure time and resource utilisation. Patient compliance with additional oral preparation on the day of or day prior to colonoscopy may be limited by tolerability concerns. In Australia, colonoscopy is a cornerstone of the National Bowel Cancer Screening Program (NBCSP) and colorectal cancer surveillance. Inadequate bowel preparation is a recognised quality indicator tracked by the Conjoint Committee for Recognition of Training in Gastrointestinal Endoscopy (CCRTGE). Polyethylene glycol preparations (e.g., MoviPrep, Glycoprep) are available on the PBS for bowel preparation. Sennosides (e.g., Senokot) are available over the counter. RACGP and GESA guidelines emphasise the importance of adequate bowel preparation for adenoma detection rate optimisation. The approximately 20% rescue failure rate identified in this review has direct implications for repeat colonoscopy scheduling, patient burden, and healthcare costs within the Australian public and private endoscopy systems. However, the methodological limitations of this review preclude its use as a basis for formal guideline revision by GESA or RACGP. Adult patients undergoing colonoscopy who have received a standard bowel preparation regimen deemed inadequate at the time of or prior to the procedure, across all colonoscopy indications including colorectal cancer screening, surveillance, and diagnostic workup

Abstract

BACKGROUND AND AIMS: An adequate bowel preparation is essential for performing high-quality ccolonoscopy; however, it remains ineffective for a certain percentage of patients. We conducted a literature search to identify evidence on salvage strategies following inadequate bowel preparation. METHODS: The search of medical literature was conducted using Medline and Google Scholar, restricted to studies published in English as a full paper. From retrieved studies, the success rate was calculated according to the rescue approaches used, including different oral- or device-assisted procedures, and pooling data of similar approaches. RESULTS: By considering data of 17 studies with 2,167 patients, an adequate colon cleaning was overall achieved in 79.3% (95%CI: 77.5-80.1). By grouping data of similar approaches, the success rate was 78.1% with oral high-volume polyethylene glycol (PEG), 75.3% with low-volume PEG, 82.5% with oral sennosides, and 84.6% following colonoscope or device-assisted preparation. CONCLUSIONS: Effective bowel cleansing is not achieved in nearly 20% of patients due to inadequate bowel preparation and although multiple approaches have been investigated, none has consistently provided adequate bowel preparation for all patients.

References

1. 1.Zullo, A., De Francesco, V., Cozza, G., Gatta, L., & Manta, R. (2026). Colon cleaning after inadequate bowel preparation: A pooled-data analysis. Journal of Gastrointestinal and Liver Diseases. https://doi.org/10.15403/jgld-6597