Effective bowel preparation, whether for colonoscopy or elective colorectal surgery, remains a cornerstone of high-quality gastrointestinal care. Adequate cleansing of the colon is essential not only for maximizing visualization during endoscopic evaluation but also for minimizing perioperative complications in surgical settings. In colonoscopy, poor bowel preparation has been linked to missed lesions, increased procedure times, and the need for early repeat procedures. In surgical contexts, suboptimal preparation can contribute to higher rates of surgical site infections and anastomotic complications. Despite its routine use, there is considerable variability in practice patterns, and the nuances in guideline recommendations can pose challenges for clinicians aiming to adopt the most current and evidence-based strategies.
This Guidelines Side-by-Side review presents a comparative analysis of the latest clinical practice guidelines from the American College of Gastroenterology (ACG), American Gastroenterological Association (AGA), and American Society for Gastrointestinal Endoscopy (ASGE), as well as the American Society of Colon and Rectal Surgeons (ASCRS). By synthesizing key recommendations, this article provides healthcare professionals with a concise, evidence-based reference to support consistent and effective decision-making in both endoscopic and surgical bowel preparation. Ultimately, the goal is to facilitate standardized best practices and improve clinical outcomes across diverse patient populations
Titles of Comparison:
| Details | Optimizing Bowel Preparation Quality for Colonoscopy | Use of Bowel Preparation in Elective Colon and Rectal Surgery |
|---|---|---|
| Authoring Organizations | US Multi-Society Task Force on Colorectal Cancer (ACG, ASGE, AGA) | American Society of Colon and Rectal Surgeons (ASCRS) |
| Publication Date | March 2025 | January 2019 |
| Use Case | Bowel prep prior to colonoscopy | Bowel preparation prior to elective colon and rectal surgery |
| Includes Graded Recommendations | Yes | Yes |
| Grading System | GRADE | GRADE |
| Comments | Includes key concepts in addition to graded recommendations | Only includes four recommendations - much more narrow in scope compared to USMSTF 2025 guideline |
| Guideline Links | Summary Full Text | Summary Full Text |
Bowel Preparation Agents
| Topic | Optimizing Bowel Preparation Quality for Colonoscopy | Use of Bowel Preparation in Elective Colon and Rectal Surgery |
|---|---|---|
| Preoperative Antibiotics in Combination with MBP | Not addressed | Recommended in combination with mechanic bowel preparation (MBP). Neither MBP or antibiotics are recommended individually, without the other. Only the combination together is recommended |
| Preoperative MBP Alone | Not recommended alone (only recommended in combination with antibiotics) | Not recommended alone (only recommended in combination with antibiotics) |
| Preoperative Antibiotics Alone | Not addressed | Not recommended alone (only recommended in combination with MBP) |
| Preoperative Enemas | Not addressed | Generally not recommended |
| Patient Education | Patients should be given both verbal and written patient education instructions for all components of the preparation, as well as patient navigation support | Not addressed |
| Dietary Modifications Before Prep | Dietary modifications should include the use of low-residue and low-fiber foods or full liquids for the early and midday meals on the day before colonoscopy when using a split-dose bowel preparation regimen for ambulatory patients at low risk for inadequate bowel preparation | Not addressed |
| Preferred Bowel Prep Formulation | No specific bowel prep purgative is superior to another, though they suggest 2 L bowel preparation regimens instead of 4 L regimen preparation | Not addressed |
| Administration | They recommend split-dose administration of bowel preparation purgatives for all patients, regardless of high-volume or low-volume preparation, though a same-day regimen is an acceptable alternative to split dosing for individuals undergoing an afternoon colonoscopy (though same-day is inferior in a morning colonoscopy) | Not addressed |
| Adjuvant Oral Simethicone | Suggested before colonoscopy | Not addressed |
| Routine Use of Nonsimethicone Adjuncts | Not recommended before colonoscopy | Not addressed |
| Quality Assessment | They rrecommend bowel preparation quality be assessed only after all washing and suctioning have been completed, using reliably understood descriptors that communicate the adequacy of the preparation | Not addressed |
| Irrigation Pumps | They suggest the routine use of irrigation pumps to assist with bowel preparation during colonoscopy | Not addressed |
| Salvage Maneuvers | They suggest the use of same-day salvage maneuvers when feasible for inadequate bowel preparations | Not addressed |
| Routine Tracking & Adequeacy Rate | They recommend routine tracking of the rate of adequate bowel preparations at the level of individual endoscopists and at the level of the endoscopy unit, and an endoscopy unit-level and individual endoscopist-level bowel preparation adequacy rate of ≥90 | Not addressed |
| Rescheduling for Inadequate Prep | When the bowel preparation is deemed inadequate to allow assigning standard screening or surveillance intervals, they recommend rescheduling a colonoscopy within 12 mo for screening or surveillance colonoscopies, and as soon as possible (i.e. generally within 3 mo) for those performed for an abnormal noncolonoscopic colorectal cancer screening test. | Not addressed |
| Patient With Previous Iadequate Prep | In the setting of a previous inadequate bowel preparation, they recommend modifications to bowel preparation instructions to include 1 or more of the following: increased attention to communicating the bowel preparation regimen instructions; increased use of patient navigation; restricting the intake of vegetables and legumes for 2 to 3 d before colonoscopy; allowing only clear liquids on the day before colonoscopy; the addition of promotility agents; treatment of underlying constipation; temporary cessation of anticholinergic, opioid, or other constipating medications; and/or the use of high-volume bowel preparation regimens | Not addressed |
| High Risk Individuals | They recommend individuals at high risk for inadequate bowel preparation quality be managed like individuals with a prior inadequate bowel preparation, with modifications to their bowel preparation regimen as previously described. They suggest the following bowel preparation regimen for individuals at high risk for inadequate bowel preparation quality: split-dose 4 L polyethylene glycol-electrolyte lavage solution +15 mg bisacodyl the afternoon before the colonoscopy and a low-residue diet 3 and 2 d before colonoscopy changing to clear-liquid diet the day before colonoscopy | Not addressed |
Key Takeaways
- Individualize Bowel Preparation Based on Procedure and Patient Risk
- While PEG-based regimens remain the gold standard for both colonoscopy and surgical preparation, selection should account for patient comorbidities, tolerability, renal function, and procedure type. Split-dose PEG is strongly supported in colonoscopy for optimizing mucosal visualization, while combination MBP with oral antibiotics is essential in surgical contexts to reduce infectious complications.
- While PEG-based regimens remain the gold standard for both colonoscopy and surgical preparation, selection should account for patient comorbidities, tolerability, renal function, and procedure type. Split-dose PEG is strongly supported in colonoscopy for optimizing mucosal visualization, while combination MBP with oral antibiotics is essential in surgical contexts to reduce infectious complications.
- Emphasize Split-Dose Regimens for Colonoscopy
- The 2025 US Multi-Society Task Force strongly supports split-dose administration of PEG to improve bowel cleanliness and adenoma detection rates. Providers should counsel patients on the importance of timing and compliance to optimize outcomes.
- The 2025 US Multi-Society Task Force strongly supports split-dose administration of PEG to improve bowel cleanliness and adenoma detection rates. Providers should counsel patients on the importance of timing and compliance to optimize outcomes.
- Oral Antibiotics Are a Cornerstone of Surgical Prep, Not Colonoscopy
- Routine use of oral antibiotics is not recommended for colonoscopy and may cause harm. However, in elective colorectal surgery, their use in conjunction with MBP significantly reduces surgical site infections and is supported by high-quality evidence.
- Routine use of oral antibiotics is not recommended for colonoscopy and may cause harm. However, in elective colorectal surgery, their use in conjunction with MBP significantly reduces surgical site infections and is supported by high-quality evidence.
- Avoid Over-Reliance on Alternative Preps
- While non-PEG options such as sodium picosulfate and oral sulfate-based agents may offer improved tolerability, they should be reserved for select patient populations. These alternatives are not routinely recommended for surgical patients due to limited data and risk profiles.
- While non-PEG options such as sodium picosulfate and oral sulfate-based agents may offer improved tolerability, they should be reserved for select patient populations. These alternatives are not routinely recommended for surgical patients due to limited data and risk profiles.
- Simethicone: A Useful Adjunct in Colonoscopy, Not Surgery
- Though not part of standard bowel prep, simethicone can be considered to enhance mucosal visualization during colonoscopy by reducing intraluminal bubbles. It has no established role in preoperative surgical protocols.
- Though not part of standard bowel prep, simethicone can be considered to enhance mucosal visualization during colonoscopy by reducing intraluminal bubbles. It has no established role in preoperative surgical protocols.
- Enemas Alone Are Inadequate
- Both guidelines discourage the use of enemas as monotherapy. Their limited efficacy does not justify routine use, though they may have adjunctive roles in specific situations.
- Both guidelines discourage the use of enemas as monotherapy. Their limited efficacy does not justify routine use, though they may have adjunctive roles in specific situations.
- Promote Patient Education and Adherence
- Regardless of regimen choice, clear patient instructions regarding dietary restrictions, fluid intake, and timing of medication are critical to achieving high-quality preparation. Poor adherence is a leading cause of suboptimal prep outcomes.
Bowel preparation is more than a procedural prerequisite, it is a critical determinant of diagnostic accuracy, surgical safety, and overall patient outcomes. The recent updates from leading gastroenterology and surgical societies underscore the importance of evidence-based, procedure-specific preparation strategies. By aligning practice with these consensus guidelines, clinicians can reduce variability, minimize complications, and enhance the quality of care across the continuum of colorectal evaluation and treatment. As new formulations and data emerge, continued adherence to rigorously developed recommendations will be essential in advancing both the science and delivery of gastrointestinal care.
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