Bowel Preparation for Colonoscopy: Entering an Era of Increased Expectations for Efficacy
Authors: Douglas K. Rex
Journal: Clinical Gastroenterology and Hepatology (2013)

Many endoscopy units fail to achieve high rates of adequate bowel preparation for colonoscopy.1Serper M. Gawron A.J. Smith S.G. et al.Patient factors that affect quality of colonoscopy preparation.Clin Gastroenterol Hepatol. 2014; 12: 451-457Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar, 2Lebwohl B. Kastrinos F. Glick M. et al.The impact of suboptimal bowel preparation on adenoma miss rates and the factors associated with early repeat colonoscopy.Gastrointest Endosc. 2011; 73: 1207-1214Abstract Full Text Full Text PDF PubMed Scopus (305) Google Scholar, 3Ness R.M. Manam R. Hoen H. et al.Predictors of inadequate bowel preparation for colonoscopy.Am J Gastroenterol. 2001; 96: 1797-1802Crossref PubMed Google Scholar, 4Harewood G.C. Sharma V.K. de Garmo P. Impact of colonoscopy preparation quality on detection of suspected colonic neoplasia.Gastrointest Endosc. 2003; 58: 76-79Abstract Full Text Full Text PDF PubMed Scopus (585) Google Scholar, 5Froehlich F. Wietlisbach V. Gonvers J.J. et al.Impact of colonic cleansing on quality and diagnostic yield of colonoscopy: the European Panel of Appropriateness of Gastrointestinal Endoscopy European multicenter study.Gastrointest Endosc. 2005; 61: 378-384Abstract Full Text Full Text PDF PubMed Scopus (724) Google Scholar, 6Hendry P.O. Jenkins J.T. Diament R.H. The impact of poor bowel preparation on colonoscopy: a prospective single centre study of 10,571 colonoscopies.Colorectal Dis. 2007; 9: 745-748Crossref PubMed Scopus (82) Google Scholar, 7Chung Y.W. Han D.S. Park K.H. et al.Patient factors predictive of inadequate bowel preparation using polyethylene glycol: a prospective study in Korea.J Clin Gastroenterol. 2009; 43: 448-452Crossref PubMed Scopus (137) Google Scholar, 8Chan W.K. Saravanan A. Manikam J. et al.Appointment waiting times and education level influence the quality of bowel preparation in adult patients undergoing colonoscopy.BMC Gastroenterol. 2011; 11: 86Crossref PubMed Scopus (90) Google Scholar, 9Fatima H. Johnson C.S. Rex D.K. Patients' description of rectal effluent and quality of bowel preparation at colonoscopy.Gastrointest Endosc. 2010; 71: 1244-1252Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar, 10Borg B.B. Gupta N.K. Zuckerman G.R. et al.Impact of obesity on bowel preparation for colonoscopy.Clin Gastroenterol Hepatol. 2009; 7: 670-675Abstract Full Text Full Text PDF PubMed Scopus (110) Google Scholar Publications are still describing that 20%–40% of preparations remain inadequate in some1Serper M. Gawron A.J. Smith S.G. et al.Patient factors that affect quality of colonoscopy preparation.Clin Gastroenterol Hepatol. 2014; 12: 451-457Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar, 2Lebwohl B. Kastrinos F. Glick M. et al.The impact of suboptimal bowel preparation on adenoma miss rates and the factors associated with early repeat colonoscopy.Gastrointest Endosc. 2011; 73: 1207-1214Abstract Full Text Full Text PDF PubMed Scopus (305) Google Scholar, 3Ness R.M. Manam R. Hoen H. et al.Predictors of inadequate bowel preparation for colonoscopy.Am J Gastroenterol. 2001; 96: 1797-1802Crossref PubMed Google Scholar, 4Harewood G.C. Sharma V.K. de Garmo P. Impact of colonoscopy preparation quality on detection of suspected colonic neoplasia.Gastrointest Endosc. 2003; 58: 76-79Abstract Full Text Full Text PDF PubMed Scopus (585) Google Scholar, 5Froehlich F. Wietlisbach V. Gonvers J.J. et al.Impact of colonic cleansing on quality and diagnostic yield of colonoscopy: the European Panel of Appropriateness of Gastrointestinal Endoscopy European multicenter study.Gastrointest Endosc. 2005; 61: 378-384Abstract Full Text Full Text PDF PubMed Scopus (724) Google Scholar, 6Hendry P.O. Jenkins J.T. Diament R.H. The impact of poor bowel preparation on colonoscopy: a prospective single centre study of 10,571 colonoscopies.Colorectal Dis. 2007; 9: 745-748Crossref PubMed Scopus (82) Google Scholar, 7Chung Y.W. Han D.S. Park K.H. et al.Patient factors predictive of inadequate bowel preparation using polyethylene glycol: a prospective study in Korea.J Clin Gastroenterol. 2009; 43: 448-452Crossref PubMed Scopus (137) Google Scholar, 8Chan W.K. Saravanan A. Manikam J. et al.Appointment waiting times and education level influence the quality of bowel preparation in adult patients undergoing colonoscopy.BMC Gastroenterol. 2011; 11: 86Crossref PubMed Scopus (90) Google Scholar, 9Fatima H. Johnson C.S. Rex D.K. Patients' description of rectal effluent and quality of bowel preparation at colonoscopy.Gastrointest Endosc. 2010; 71: 1244-1252Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar, 10Borg B.B. Gupta N.K. Zuckerman G.R. et al.Impact of obesity on bowel preparation for colonoscopy.Clin Gastroenterol Hepatol. 2009; 7: 670-675Abstract Full Text Full Text PDF PubMed Scopus (110) Google Scholar and perhaps many centers. Bowel preparation can be reasonably considered inadequate when the examination has to be repeated at an earlier date than would otherwise be indicated, solely because of preparation quality. The substantial negative consequences of inadequate preparation are increasingly recognized (Table 1).2Lebwohl B. Kastrinos F. Glick M. et al.The impact of suboptimal bowel preparation on adenoma miss rates and the factors associated with early repeat colonoscopy.Gastrointest Endosc. 2011; 73: 1207-1214Abstract Full Text Full Text PDF PubMed Scopus (305) Google Scholar, 11Rex D.K. Johnson D.A. Anderson J.C. et al.American College of Gastroenterology guidelines for colorectal cancer screening 2008.Am J Gastroenterol. 2009; 104: 739-750Crossref PubMed Scopus (1169) Google Scholar, 12Chokshi R.V. Hovis C.E. Hollander T. et al.Prevalence of missed adenomas in patients with inadequate bowel preparation on screening colonoscopy.Gastrointest Endosc. 2012; 75: 1197-1203Abstract Full Text Full Text PDF PubMed Scopus (236) Google Scholar, 13Longcroft–Wheaton G. Bhandari P. Same-day bowel cleansing regimen is superior to a split-dose regimen over two days for afternoon colonoscopy: results from a large prospective series.J Clin Gastroenterol. 2012; 46: 57-61Crossref PubMed Scopus (51) Google Scholar, 14Rex D.K. Imperiale T.F. Latinovich D.R. et al.Impact of bowel preparation on efficiency and cost of colonoscopy.Am J Gastroenterol. 2002; 97: 1696-1700Crossref PubMed Google ScholarTable 1Negative Consequence of Inadequate Bowel Preparation for ColonoscopyConsequenceReferencesLower detection of small adenomas2Lebwohl B. Kastrinos F. Glick M. et al.The impact of suboptimal bowel preparation on adenoma miss rates and the factors associated with early repeat colonoscopy.Gastrointest Endosc. 2011; 73: 1207-1214Abstract Full Text Full Text PDF PubMed Scopus (305) Google Scholar, 4Harewood G.C. Sharma V.K. de Garmo P. Impact of colonoscopy preparation quality on detection of suspected colonic neoplasia.Gastrointest Endosc. 2003; 58: 76-79Abstract Full Text Full Text PDF PubMed Scopus (585) Google Scholar, 12Chokshi R.V. Hovis C.E. Hollander T. et al.Prevalence of missed adenomas in patients with inadequate bowel preparation on screening colonoscopy.Gastrointest Endosc. 2012; 75: 1197-1203Abstract Full Text Full Text PDF PubMed Scopus (236) Google Scholar, 13Longcroft–Wheaton G. Bhandari P. Same-day bowel cleansing regimen is superior to a split-dose regimen over two days for afternoon colonoscopy: results from a large prospective series.J Clin Gastroenterol. 2012; 46: 57-61Crossref PubMed Scopus (51) Google ScholarLower detection of large adenomas2Lebwohl B. Kastrinos F. Glick M. et al.The impact of suboptimal bowel preparation on adenoma miss rates and the factors associated with early repeat colonoscopy.Gastrointest Endosc. 2011; 73: 1207-1214Abstract Full Text Full Text PDF PubMed Scopus (305) Google Scholar, 5Froehlich F. Wietlisbach V. Gonvers J.J. et al.Impact of colonic cleansing on quality and diagnostic yield of colonoscopy: the European Panel of Appropriateness of Gastrointestinal Endoscopy European multicenter study.Gastrointest Endosc. 2005; 61: 378-384Abstract Full Text Full Text PDF PubMed Scopus (724) Google ScholarLoss of patients to follow-up before evaluation completed2Lebwohl B. Kastrinos F. Glick M. et al.The impact of suboptimal bowel preparation on adenoma miss rates and the factors associated with early repeat colonoscopy.Gastrointest Endosc. 2011; 73: 1207-1214Abstract Full Text Full Text PDF PubMed Scopus (305) Google ScholarLonger time to achieve cecal intubation5Froehlich F. Wietlisbach V. Gonvers J.J. et al.Impact of colonic cleansing on quality and diagnostic yield of colonoscopy: the European Panel of Appropriateness of Gastrointestinal Endoscopy European multicenter study.Gastrointest Endosc. 2005; 61: 378-384Abstract Full Text Full Text PDF PubMed Scopus (724) Google ScholarLonger time to complete withdrawal5Froehlich F. Wietlisbach V. Gonvers J.J. et al.Impact of colonic cleansing on quality and diagnostic yield of colonoscopy: the European Panel of Appropriateness of Gastrointestinal Endoscopy European multicenter study.Gastrointest Endosc. 2005; 61: 378-384Abstract Full Text Full Text PDF PubMed Scopus (724) Google ScholarIncreased costaFor each 1% of examinations requiring repeat examination at earlier date, the total cost of delivering colonoscopy increases by ∼1%.14Rex D.K. Imperiale T.F. Latinovich D.R. et al.Impact of bowel preparation on efficiency and cost of colonoscopy.Am J Gastroenterol. 2002; 97: 1696-1700Crossref PubMed Google Scholara For each 1% of examinations requiring repeat examination at earlier date, the total cost of delivering colonoscopy increases by ∼1%. Open table in a new tab Guidelines on the technical performance of colonoscopy have not recommended specific targets for rates of adequate preparation15Rex D.K. Bond J.H. Winawer S. et al.Quality in the technical performance of colonoscopy and the continuous quality improvement process for colonoscopy: recommendations of the U.S. Multi-Society Task Force on Colorectal Cancer.Am J Gastroenterol. 2002; 97: 1296-1308Crossref PubMed Scopus (860) Google Scholar, 16Rex D.K. Petrini J.L. Baron T.H. et al.Quality indicators for colonoscopy.Gastrointest Endosc. 2006; 63: S16-S28Abstract Full Text Full Text PDF PubMed Scopus (436) Google Scholar because these rates are partly related to patient factors, such as poor socioeconomic status,8Chan W.K. Saravanan A. Manikam J. et al.Appointment waiting times and education level influence the quality of bowel preparation in adult patients undergoing colonoscopy.BMC Gastroenterol. 2011; 11: 86Crossref PubMed Scopus (90) Google Scholar, 17Nguyen D.L. Wieland M. Risk factors predictive of poor quality preparation during average risk colonoscopy screening: the importance of health literacy.J Gastrointestin Liver Dis. 2010; 19: 369-372PubMed Google Scholar, 18Lebwohl B. Wang T.C. Neugut A.I. Socioeconomic and other predictors of colonoscopy preparation quality.Dig Dis Sci. 2010; 55: 2014-2020Crossref PubMed Scopus (122) Google Scholar, 19Smith S.G. von Wagner C. McGregor L.M. et al.The influence of health literacy on comprehension of a colonoscopy preparation information leaflet.Dis Colon Rectum. 2012; 55: 1074-1080Crossref PubMed Scopus (53) Google Scholar that typically vary between populations. Given these variations, it seemed unfair to expect endoscopists caring for poor patients (eg, in safety net hospitals) to achieve the same rates of adequate preparation achieved by endoscopists serving privately insured patients. However, the consequences of inadequate preparation are so significant that in the near future there will likely be recommendations from gastrointestinal professional societies that endoscopists meet or exceed a specific and quite high threshold for the fraction of patients with adequate preparation. These recommendations will ask many clinicians to do better or much better. What is the path to improved performance? The first step is setting efficacy as the priority. Bowel preparations are judged and selected by their efficacy, tolerability, and safety and, for some patients, the out-of-pocket costs. That a preparation must be devoid of specific and substantial safety issues is illustrated by the devastating effect on sodium phosphate use that followed recognition of the rare event of phosphate nephropathy.20Markowitz G.S. Stokes M.B. Radhakrishnan J. et al.Acute phosphate nephropathy following oral sodium phosphate bowel purgative: an underrecognized cause of chronic renal failure.J Am Soc Nephrol. 2005; 16: 3389-3396Crossref PubMed Scopus (324) Google Scholar Assuming that all of the commonly used preparations in the United States are now devoid of such specific and serious organ toxicity, the choice of preparation revolves around efficacy versus tolerability. Efficacy and tolerability are related, and together constitute the main ingredients of "effectiveness." If the preparation is not well tolerated, even if otherwise efficacious, it will not be ingested and will be less effective (Figure 1). Both efficacy and tolerability are important. Selection of a preparation would be easy if one preparation was clearly superior at both efficacy and tolerability, but such a preparation does not yet exist. The commercial success that followed Food and Drug Administration (FDA) approval of some low-volume preparations with relatively poor efficacy21DiPalma J.A. Wolff B.G. Meagher A. et al.Comparison of reduced volume versus four liters sulfate-free electrolyte lavage solutions for colonoscopy colon cleansing.Am J Gastroenterol. 2003; 98: 2187-2191Crossref PubMed Scopus (120) Google Scholar suggests that tolerability has been the priority for many endoscopists. However, given the impact of impaired efficacy (Table 1), the expectation of targets for rates of adequate preparation in the near future, and remembering that the whole point of the preparation is to clean the colon for effective examination and prevention of colorectal cancer, efficacy should be the first priority. During every "routine" colonoscopy, the modern expert undertakes an obsessive-compulsive hunt for precancerous lesions, many of which are characterized foremost by a subtle appearance. This hunt is only feasible with adequate preparation. Higher rates of adequate preparation are the first priority in bowel preparation. With preparation efficacy as the priority, several major conclusions of modern bowel preparation science (Table 2) inform endoscopy unit policy.22Kilgore T.W. Abdinoor A.A. Szary N.M. et al.Bowel preparation with split-dose polyethylene glycol before colonoscopy: a meta-analysis of randomized controlled trials.Gastrointest Endosc. 2011; 73: 1240-1245Abstract Full Text Full Text PDF PubMed Scopus (209) Google Scholar, 23Gurudu S.R. Ramirez F.C. Harrison M.E. et al.Increased adenoma detection rate with system-wide implementation of a split-dose preparation for colonoscopy.Gastrointest Endosc. 2012; 76: 603-608Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar, 24Seo E.H. Kim T.O. Park M.J. et al.Optimal preparation-to-colonoscopy interval in split-dose PEG bowel preparation determines satisfactory bowel preparation quality: an observational prospective study.Gastrointest Endosc. 2012; 75: 583-590Abstract Full Text Full Text PDF PubMed Scopus (98) Google Scholar, 25Matro R. Shnitser A. Spodik M. et al.Efficacy of morning-only compared with split-dose polyethylene glycol electrolyte solution for afternoon colonoscopy: a randomized controlled single-blind study.Am J Gastroenterol. 2010; 105: 1954-1961Crossref PubMed Scopus (68) Google Scholar, 26Varughese S. Kumar A.R. George A. et al.Morning-only one-gallon polyethylene glycol improves bowel cleansing for afternoon colonoscopies: a randomized endoscopist-blinded prospective study.Am J Gastroenterol. 2010; 105: 2368-2374Crossref PubMed Scopus (66) Google Scholar, 27Enestvedt B.K. Tofani C. Laine L.A. et al.4-Liter split-dose polyethylene glycol is superior to other bowel preparations, based on systematic review and meta-analysis.Clin Gastroenterol Hepatol. 2012; 10: 1225-1231Abstract Full Text Full Text PDF PubMed Scopus (128) Google Scholar, 28Sipe B.W. Fischer M. Baluyut A.R. et al.A low-residue diet improved patient satisfaction with split-dose oral sulfate solution without impairing colonic preparation.Gastrointest Endosc. 2013; 77: 932-936Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar First, all preparations can be split,22Kilgore T.W. Abdinoor A.A. Szary N.M. et al.Bowel preparation with split-dose polyethylene glycol before colonoscopy: a meta-analysis of randomized controlled trials.Gastrointest Endosc. 2011; 73: 1240-1245Abstract Full Text Full Text PDF PubMed Scopus (209) Google Scholar, 23Gurudu S.R. Ramirez F.C. Harrison M.E. et al.Increased adenoma detection rate with system-wide implementation of a split-dose preparation for colonoscopy.Gastrointest Endosc. 2012; 76: 603-608Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar and some can be given entirely on the same day as the procedure, with benefits of improved cleansing and tolerability. Same-day dosing is neat for afternoon procedures and less disruptive to work the day before colonoscopy.24Seo E.H. Kim T.O. Park M.J. et al.Optimal preparation-to-colonoscopy interval in split-dose PEG bowel preparation determines satisfactory bowel preparation quality: an observational prospective study.Gastrointest Endosc. 2012; 75: 583-590Abstract Full Text Full Text PDF PubMed Scopus (98) Google Scholar, 25Matro R. Shnitser A. Spodik M. et al.Efficacy of morning-only compared with split-dose polyethylene glycol electrolyte solution for afternoon colonoscopy: a randomized controlled single-blind study.Am J Gastroenterol. 2010; 105: 1954-1961Crossref PubMed Scopus (68) Google Scholar, 26Varughese S. Kumar A.R. George A. et al.Morning-only one-gallon polyethylene glycol improves bowel cleansing for afternoon colonoscopies: a randomized endoscopist-blinded prospective study.Am J Gastroenterol. 2010; 105: 2368-2374Crossref PubMed Scopus (66) Google Scholar Those who worry about increased aspiration with split dosing can be reassured by two studies showing no increase in residual gastric volumes.29Huffman M. Unger R.Z. Thatikonda C. et al.Split-dose bowel preparation for colonoscopy and residual gastric fluid volume: an observational study.Gastrointest Endosc. 2010; 72: 516-522Abstract Full Text Full Text PDF PubMed Scopus (61) Google Scholar, 30Agrawal D. Robbins R. Rockey D.C. Gastric residual volume is trivial soon after polyethylene glycol bowel preparation.Gastrointest Endosc. 2013; 77: AB149-AB150Abstract Full Text Full Text PDF Google ScholarTable 2Major Conclusions of Recent Bowel Preparation StudiesReferencesSplit-dosing and same-day dosing are more effective than evening-before dosing22Kilgore T.W. Abdinoor A.A. Szary N.M. et al.Bowel preparation with split-dose polyethylene glycol before colonoscopy: a meta-analysis of randomized controlled trials.Gastrointest Endosc. 2011; 73: 1240-1245Abstract Full Text Full Text PDF PubMed Scopus (209) Google Scholar, 23Gurudu S.R. Ramirez F.C. Harrison M.E. et al.Increased adenoma detection rate with system-wide implementation of a split-dose preparation for colonoscopy.Gastrointest Endosc. 2012; 76: 603-608Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar, 24Seo E.H. Kim T.O. Park M.J. et al.Optimal preparation-to-colonoscopy interval in split-dose PEG bowel preparation determines satisfactory bowel preparation quality: an observational prospective study.Gastrointest Endosc. 2012; 75: 583-590Abstract Full Text Full Text PDF PubMed Scopus (98) Google Scholar, 25Matro R. Shnitser A. Spodik M. et al.Efficacy of morning-only compared with split-dose polyethylene glycol electrolyte solution for afternoon colonoscopy: a randomized controlled single-blind study.Am J Gastroenterol. 2010; 105: 1954-1961Crossref PubMed Scopus (68) Google Scholar, 26Varughese S. Kumar A.R. George A. et al.Morning-only one-gallon polyethylene glycol improves bowel cleansing for afternoon colonoscopies: a randomized endoscopist-blinded prospective study.Am J Gastroenterol. 2010; 105: 2368-2374Crossref PubMed Scopus (66) Google ScholarSplit-dosing is better tolerated than evening-before dosing22Kilgore T.W. Abdinoor A.A. Szary N.M. et al.Bowel preparation with split-dose polyethylene glycol before colonoscopy: a meta-analysis of randomized controlled trials.Gastrointest Endosc. 2011; 73: 1240-1245Abstract Full Text Full Text PDF PubMed Scopus (209) Google Scholar4-L split-dose PEG-ELS remains the gold standard forefficacy among standard preparations27Enestvedt B.K. Tofani C. Laine L.A. et al.4-Liter split-dose polyethylene glycol is superior to other bowel preparations, based on systematic review and meta-analysis.Clin Gastroenterol Hepatol. 2012; 10: 1225-1231Abstract Full Text Full Text PDF PubMed Scopus (128) Google ScholarFiber-free and low-residue diets the day before colonoscopy do not impair and may improve preparation quality in selected patients28Sipe B.W. Fischer M. Baluyut A.R. et al.A low-residue diet improved patient satisfaction with split-dose oral sulfate solution without impairing colonic preparation.Gastrointest Endosc. 2013; 77: 932-936Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar Open table in a new tab A second conclusion of preparation studies is that inadequate preparation is predictable to a significant degree (Table 3). There are two sets of predictors, one encompassing medical factors,3Ness R.M. Manam R. Hoen H. et al.Predictors of inadequate bowel preparation for colonoscopy.Am J Gastroenterol. 2001; 96: 1797-1802Crossref PubMed Google Scholar, 7Chung Y.W. Han D.S. Park K.H. et al.Patient factors predictive of inadequate bowel preparation using polyethylene glycol: a prospective study in Korea.J Clin Gastroenterol. 2009; 43: 448-452Crossref PubMed Scopus (137) Google Scholar, 9Fatima H. Johnson C.S. Rex D.K. Patients' description of rectal effluent and quality of bowel preparation at colonoscopy.Gastrointest Endosc. 2010; 71: 1244-1252Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar, 10Borg B.B. Gupta N.K. Zuckerman G.R. et al.Impact of obesity on bowel preparation for colonoscopy.Clin Gastroenterol Hepatol. 2009; 7: 670-675Abstract Full Text Full Text PDF PubMed Scopus (110) Google Scholar, 31Hassan C. Fuccio L. Bruno M. et al.A predictive model identifies patients most likely to have inadequate bowel preparation for colonoscopy.Clin Gastroenterol Hepatol. 2012; 10: 501-506Abstract Full Text Full Text PDF PubMed Scopus (183) Google Scholar, 32Verma S. Fogel J. Beyda D.J. et al.Chronic methadone use, poor bowel visualization and failed colonoscopy: a preliminary study.World J Gastroenterol. 2012; 18: 4350-4356Crossref PubMed Scopus (13) Google Scholar and the other relates to such issues as socioeconomic status, educational level, insurance type, and health literacy.8Chan W.K. Saravanan A. Manikam J. et al.Appointment waiting times and education level influence the quality of bowel preparation in adult patients undergoing colonoscopy.BMC Gastroenterol. 2011; 11: 86Crossref PubMed Scopus (90) Google Scholar, 17Nguyen D.L. Wieland M. Risk factors predictive of poor quality preparation during average risk colonoscopy screening: the importance of health literacy.J Gastrointestin Liver Dis. 2010; 19: 369-372PubMed Google Scholar, 18Lebwohl B. Wang T.C. Neugut A.I. Socioeconomic and other predictors of colonoscopy preparation quality.Dig Dis Sci. 2010; 55: 2014-2020Crossref PubMed Scopus (122) Google Scholar, 19Smith S.G. von Wagner C. McGregor L.M. et al.The influence of health literacy on comprehension of a colonoscopy preparation information leaflet.Dis Colon Rectum. 2012; 55: 1074-1080Crossref PubMed Scopus (53) Google Scholar These latter factors predict an increased risk of the patient not following the preparation instructions. The article by Serper and coworkers1Serper M. Gawron A.J. Smith S.G. et al.Patient factors that affect quality of colonoscopy preparation.Clin Gastroenterol Hepatol. 2014; 12: 451-457Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar in this issue of Clincal Gastroenterology and Hepatology identifies a role for "patient activation," which refers to how engaged a patient is in their health care. Lower patient activation predicted worse preparation quality. Conversion of this and similar concepts into simple surveys that could be used by endoscopy units to identify patients at risk for failure would be helpful. In the interim, factors as simple as Medicaid insurance can be used as a marker of risk.17Nguyen D.L. Wieland M. Risk factors predictive of poor quality preparation during average risk colonoscopy screening: the importance of health literacy.J Gastrointestin Liver Dis. 2010; 19: 369-372PubMed Google Scholar, 18Lebwohl B. Wang T.C. Neugut A.I. Socioeconomic and other predictors of colonoscopy preparation quality.Dig Dis Sci. 2010; 55: 2014-2020Crossref PubMed Scopus (122) Google ScholarTable 3Predictors of Inadequate Bowel Preparation for ColonoscopyReferencesMedical factors3Ness R.M. Manam R. Hoen H. et al.Predictors of inadequate bowel preparation for colonoscopy.Am J Gastroenterol. 2001; 96: 1797-1802Crossref PubMed Google Scholar, 9Fatima H. Johnson C.S. Rex D.K. Patients' description of rectal effluent and quality of bowel preparation at colonoscopy.Gastrointest Endosc. 2010; 71: 1244-1252Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar, 10Borg B.B. Gupta N.K. Zuckerman G.R. et al.Impact of obesity on bowel preparation for colonoscopy.Clin Gastroenterol Hepatol. 2009; 7: 670-675Abstract Full Text Full Text PDF PubMed Scopus (110) Google Scholar, 31Hassan C. Fuccio L. Bruno M. et al.A predictive model identifies patients most likely to have inadequate bowel preparation for colonoscopy.Clin Gastroenterol Hepatol. 2012; 10: 501-506Abstract Full Text Full Text PDF PubMed Scopus (183) Google Scholar, 32Verma S. Fogel J. Beyda D.J. et al.Chronic methadone use, poor bowel visualization and failed colonoscopy: a preliminary study.World J Gastroenterol. 2012; 18: 4350-4356Crossref PubMed Scopus (13) Google Scholar Chronic constipation Use of constipating medications, especially opioids and tricyclics Diabetes mellitus Obesity Prior resection of the colon Prior inadequate preparation for colonoscopyOther patient factors1Serper M. Gawron A.J. Smith S.G. et al.Patient factors that affect quality of colonoscopy preparation.Clin Gastroenterol Hepatol. 2014; 12: 451-457Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar, 8Chan W.K. Saravanan A. Manikam J. et al.Appointment waiting times and education level influence the quality of bowel preparation in adult patients undergoing colonoscopy.BMC Gastroenterol. 2011; 11: 86Crossref PubMed Scopus (90) Google Scholar, 17Nguyen D.L. Wieland M. Risk factors predictive of poor quality preparation during average risk colonoscopy screening: the importance of health literacy.J Gastrointestin Liver Dis. 2010; 19: 369-372PubMed Google Scholar, 18Lebwohl B. Wang T.C. Neugut A.I. Socioeconomic and other predictors of colonoscopy preparation quality.Dig Dis Sci. 2010; 55: 2014-2020Crossref PubMed Scopus (122) Google Scholar, 19Smith S.G. von Wagner C. McGregor L.M. et al.The influence of health literacy on comprehension of a colonoscopy preparation information leaflet.Dis Colon Rectum. 2012; 55: 1074-1080Crossref PubMed Scopus (53) Google Scholar Medicaid insurance Lower educational level English not first language Low health literacy Low patient activation Open table in a new tab The response to medical predictors of poor preparation is a more aggressive preparation regimen. In this regard the commonly held perception that low-volume (eg, 2-L polyethylene glycol [PEG] electrolyte lavage solution [ELS]) preparations are as efficacious as 4-L preparations is unfortunate. Clinical trials of bowel preparation are often designed as noninferiority studies.21DiPalma J.A. Wolff B.G. Meagher A. et al.Comparison of reduced volume versus four liters sulfate-free electrolyte lavage solutions for colonoscopy colon cleansing.Am J Gastroenterol. 2003; 98: 2187-2191Crossref PubMed Scopus (120) Google Scholar, 33DiPalma J.A. Rodriguez R. McGowan J. et al.A randomized clinical study evaluating the safety and efficacy of a new, reduced-volume, oral sulfate colon-cleansing preparation for colonoscopy.Am J Gastroenterol. 2009; 104: 2275-2284Crossref PubMed Scopus (110) Google Scholar, 34Katz P.O. Rex D.K. Epstein M. et al.A dual-action, low-volume bowel cleanser administered the day before colonoscopy: results from the SEE CLEAR II study.Am J Gastroenterol. 2013; 108: 401-409Crossref PubMed Scopus (70) Google Scholar They are not powered to prove equivalence. Patients with chronic constipation are often excluded from the studies. In these trials a low-volume preparation can meet a predetermined cut-off for noninferiority while simultaneously demonstrating a clinically important absolute increase in the rate of inadequate preparation.21DiPalma J.A. Wolff B.G. Meagher A. et al.Comparison of reduced volume versus four liters sulfate-free electrolyte lavage solutions for colonoscopy colon cleansing.Am J Gastroenterol. 2003; 98: 2187-2191Crossref PubMed Scopus (120) Google Scholar When low-volume preparations are compared with each other, they may show similar rates of efficacy and meet noninferiority margins but also show absolute rates of inadequate preparation that are concerning34Katz P.O. Rex D.K. Epstein M. et al.A dual-action, low-volume bowel cleanser administered the day before colonoscopy: results from the SEE CLEAR II study.Am J Gastroenterol. 2013; 108: 401-409Crossref PubMed Scopus (70) Google Scholar but often ignored. A meta-analysis found that 4-L split-dose PEG-ELS is still the gold standard for efficacy.27Enestvedt B.K. Tofani C. Laine L.A. et al.4-Liter split-dose polyethylene glycol is superior to other bowel preparations, based on systematic review and meta-analysis.Clin Gastroenterol Hepatol. 2012; 10: 1225-1231Abstract Full Text Full Text PDF PubMed Scopus (128) Google Scholar The idea that 2-L PEG-ELS is as effective as 4 L does not pass the "logic" test. Experienced colonoscopists know that some patients need 8 or more liters of PEG-ELS to clear their colons. It makes perfect sense that 4 L succeeds in some patients in whom 2 L fails. The goal is to identify those at risk for failure and triage them to a more aggressive preparation, such as 4-L PEG-ELS or a low-volume preparation that is modified for more efficacy. Home-made modifications to standard preparations (eg, addition of a bottle of magnesium citrate or doses of stimulant laxative) that provide extra cleansing for patients at risk of failure are easy to criticize based on lack of supporting data. It is also easy to understand the anecdotal impression that endoscopy units often develop such modifications to standard preparations so they can achieve adequate cleansing in the "hard to prepare" patient, avoid the complaints associated with 4-L PEG-ELS, and respond to the patient who has taken 4-L PEG-ELS and is determined to not take it again. Clinicians cannot be expected to rely only on FDA-approved bowel preparations when the types of patients who present with inadequate preparation have often been excluded from the trials that led to FDA approval. At the same time, there is no point in torturing healthy nonconstipated patients with 4 L of PEG-ELS routinely when they can achieve high rates of adequate preparation using low-volume preparations. The system for prescribing preparations can maximize both efficacy and tolerability when it is informed and flexible. The solutions to such factors as low health literacy and low patient activation that are seen to some extent in all populations and are very prevalent in populations with lower socioeconomic status are education, motivation, and reminders.35Spiegel B.M. Talley J. Shekelle P. et al.Development and validation of a novel patient educational booklet to enhance colonoscopy preparation.Am J Gastroenterol. 2011; 106: 875-883Crossref PubMed Scopus (111) Google Scholar, 36Rosenfeld G. Krygier D. Enns R.A. et al.The impact of patient education on the quality of inpatient bowel preparation for colonoscopy.Can J Gastroenterol. 2010; 24: 543-546Crossref PubMed Scopus (56) Google Scholar, 37Tae J.W. Lee J.C. Hong S.J. et al.Impact of patient education with cartoon visual aids on the quality of bowel preparation for colonoscopy.Gastrointest Endosc. 2012; 76: 804-811Abstract Full Text Full Text PDF PubMed Scopus (114) Google Scholar The ultimate expression of these principles is patient navigation,38Cavanagh M.F. Lane D.S. Messina C.R. et al.Clinical case management and navigation for colonoscopy screening in an academic medical center.Cancer. 2013; 119: 2894-2904Crossref PubMed Scopus (20) Google Scholar, 39Jandorf L. Braschi C. Ernstoff E. et al.Culturally targeted patient navigation for increasing African Americans' adherence to screening colonoscopy: a randomized clinical trial.Cancer Epidemiol Biomarkers Prev. 2013; 22: 1577-1587Crossref PubMed Scopus (72) Google Scholar, 40Braschi C.D. Sly J.R. Singh S. et al.Increasing colonoscopy screening for Latino Americans through a patient navigation model: a randomized clinical trial.J Immigr Minor Health. 2013 Jun 5; (Epub ahead of print)Google Scholar which has proved very cost-effective for safety-net hospitals.41Jandorf L. Stossel L.M. Cooperman J.L. et al.Cost analysis of a patient navigation system to increase screening colonoscopy adherence among urban minorities.Cancer. 2013; 119: 612-620Crossref PubMed Scopus (44) Google Scholar More work is needed to refine and simplify identification of at-risk patients and establish optimal tools and techniques to educate and improve adherence to instructions. Finally, the process of optimizing bowel preparation continues at the endoscopy unit and during the procedure. Persisting brown color of the rectal effluent on arrival predicts poor preparation.9Fatima H. Johnson C.S. Rex D.K. Patients' description of rectal effluent and quality of bowel preparation at colonoscopy.Gastrointest Endosc. 2010; 71: 1244-1252Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar Such patients can be encouraged to drink more preparation and undergo colonoscopy later in the day, stopping intake when the effluent is clear or yellow, and waiting 2 hours before sedation. Alternatively, large-volume enemas can be administered. Techniques for administering salvage enemas or laxatives during colonoscopy are available42Horiuchi A. Nakayama Y. Kajiyama M. et al.Colonoscopic enema as rescue for inadequate bowel preparation before colonoscopy: a prospective, observational study.Colorectal Dis. 2012; 14: e735-e739Crossref PubMed Scopus (18) Google Scholar but less desirable if they lead to charges for 2 procedures. It is best to minimize the need for such measures by maximizing the efficacy of home preparation. During the procedure, much can be done with the water jet to remove bubbles, mucus, and pools of semisolids. Various special cleansing devices may help in particularly bad preparations.43Kiesslich R. Schuster N. Hoffman A. et al.MedJet–a new CO2-based disposable cleaning device allows safe and effective bowel cleansing during colonoscopy: a pilot study.Endoscopy. 2012; 44: 767-771Crossref PubMed Scopus (12) Google Scholar, 44Eliakim R. Yassin K. Lachter J. et al.A novel device to improve colon cleanliness during colonoscopy.Endoscopy. 2012; 44: 655-659Crossref PubMed Scopus (15) Google Scholar, 45Rigaux J. Juriens I. Deviere J. A novel system for the improvement of colonic cleansing during colonoscopy.Endoscopy. 2012; 44: 703-706Crossref PubMed Scopus (18) Google Scholar Importantly, the bowel preparation should only be rated after this intraprocedural cleansing has occurred. Of the validated bowel preparation scales, two (Aronchick46Aronchick C.A. Lipshutz W.H. Wright S.H. et al.A novel tableted purgative for colonoscopic preparation: efficacy and safety comparisons with Colyte and Fleet Phospho–Soda.Gastrointest Endosc. 2000; 52: 346-352Abstract Full Text Full Text PDF PubMed Scopus (311) Google Scholar and Ottawa47Rostom A. Jolicoeur E. Validation of a new scale for the assessment of bowel preparation quality.Gastrointest Endosc. 2004; 59: 482-486Abstract Full Text Full Text PDF PubMed Scopus (354) Google Scholar) take into account retained fluid, as does the nonvalidated scale used in Braintree trials.33DiPalma J.A. Rodriguez R. McGowan J. et al.A randomized clinical study evaluating the safety and efficacy of a new, reduced-volume, oral sulfate colon-cleansing preparation for colonoscopy.Am J Gastroenterol. 2009; 104: 2275-2284Crossref PubMed Scopus (110) Google Scholar Retained fluid is of no interest to patient care and decision making, because it can be completely suctioned and does not interfere with visualization. Cleaning up is part of colonoscopy. Although retained removable material may be of interest in clinical trials, it is not of interest in clinical practice. The bowel preparation should be rated after cleansing has been completed to whatever degree is feasible, because that is the point from where the inspection is conducted and the need for repeat procedure at an early interval is judged. Figure 2 is an algorithm for one approach to improved bowel preparation quality based on available evidence. Useful refinements to preparation instructions that improve efficacy and tolerability continue to appear in the literature.48Church J. Bast J. Elayi E. et al.Keeping the cecum clean: a randomized, prospective, placebo-controlled trial of loperamide as part of preparation for colonoscopy.Dis Colon Rectum. 2013; 56: 120-125Crossref PubMed Scopus (4) Google Scholar, 49Sharara A.I. El-Halabi M.M. Abou Fadel C.G. et al.Sugar-free menthol candy drops improve the palatability and bowel cleansing effect of polyethylene glycol electrolyte solution.Gastrointest Endosc. 2013; 78: 886-891Abstract Full Text Full Text PDF PubMed Scopus (16) Google Scholar Rather than demonstrating a proved pathway to high rates of adequate preparation, the algorithm illustrates categories of considerations that endoscopy units could use in designing protocols directed toward achieving higher rates of adequate preparation and specific to their patient populations. Success in achieving adequate rates of preparation and thereby recommending appropriate intervals should be measured, with high expectations, to avoid the consequences seen in Table 1. Patient Factors That Affect Quality of Colonoscopy PreparationClinical Gastroenterology and HepatologyVol. 12Issue 3PreviewOptimal colonoscopy preparation requires patients to adhere to written instructions and be activated to complete the task. Among patients with chronic disease, health literacy and patient activation have been associated with outcome, but these factors have not been studied for colonoscopy. We examined the association between health literacy, patient activation, and quality of bowel preparation. Full-Text PDF Issue HighlightsClinical Gastroenterology and HepatologyVol. 12Issue 3PreviewMucosal healing is now viewed as an important treatment end point for patients with Crohn's disease (CD). However, mucosal healing does not always correlate with clinical remission—a long-standing end point of clinical care and clinical trials alike. In this issue of Clinical Gastroenterology and Hepatology, Colombel et al explore a new end point in CD that represents a state of deep remission (DR), defined as a composite of clinical as well as endoscopic remission. Full-Text PDF