Maxprep_gense07

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Department of Medicine (Gastroenterology) Department of Medicine (Gastroenterology) The Mount Sinai School of Medicine The Mount Sinai School of Medicine Furthermore, suboptimal bowel preparation leads to prolonged procedure times, lower rates of cecal intuba- tion, reduced screening intervals, higher screeningcosts, and possibly, an increased risk for procedure- related complications. Consequently, the adoption of Tcancer is highly dependent upon more effective methods of bowel cleansing and a greater emphasis on patient compliance with prepara- tion instructions will improve the effectiveness and effi-ciency of colonoscopy, as well as minimize the risk for Bowel Preparations
The available purgatives for colonoscopy can be clas- sified into 1 of 3 categories: osmotic agents, polyethyl- ene glycol–based (PEG) solutions, and stimulants.
Osmotic laxatives increase intraluminal water by pro- examinations, results in missed adenomas.1 moting the passage of extracellular fluid across thebowel wall. Examples of osmotic preparations includesodium phosphate (NaP), magnesium citrate, and man-nitol. The PEG-based solutions consist of a high molec-ular weight nonabsorbable polymer in a dilute elec-trolyte solution. PEG solutions are designed to beosmotically balanced, limiting the exchange of fluid andelectrolytes across the colonic membrane. Stimulantlaxatives work by increasing smooth muscle activitywithin the wall of the colon. Examples of stimulantpurgatives include senna, bisacodyl, and sodium pico-sulfate. Dietary modification, consisting of a clear liquidor a low fiber diet for 24 hours prior to the procedure, is G A S T R O E N T E R O L O G Y & E N D O S C O P Y N E W S S P E C I A L E D I T I O N • 2 0 0 7 usually combined with a purgative regimen. This section gastric outlet obstruction, high-grade small bowel provides a brief overview of the available purgatives for obstruction, and suspected bowel perforation. bowel preparation (Table). Several comprehensivereviews on the comparative efficacy, safety, and tolera- bility of these agents have recently been published, and Oral NaP solution (Fleet Phospho-soda Oral Saline readers wanting a more in-depth analysis of this subject Laxative, CB Fleet) contains monobasic and dibasic sodium phosphate, and is usually administered as 2, 45-mL doses 10 to 12 hours apart. Patients are instructed to consume significant quantities of liquid (64 oz) during A variety of PEG-based lavage regimens are current- the preparation in order to prevent dehydration and ly available for bowel cleansing prior to colonoscopy.
electrolyte disturbances. The mean onset and duration These preparations differ with respect to volume of of bowel activity following ingestion of the first dose is lavage solution, electrolyte content, molecular weight of 1.7 and 4.6 hours, respectively.9 It is recommended that the polymer, requirement for an adjunctive laxative, and NaP not be used in patients with impaired renal function the presence of artificial sweeteners. Commercially (creatinine clearance <60 mL/min), congestive heart available PEG lavage solutions include the traditional 4- failure, or hypercalcemia. In addition, caution is advised L preparations (GoLYTELY [Braintree], Colyte [Schwarz when using NaP in individuals with pre-existing dehy- Pharma], NuLYTELY [Braintree], TriLyte [Schwarz dration, electrolyte disturbances, or an inability to con- Pharma]), and low-volume 2-L regimens (HalfLytely sume an appropriate quantity of fluids. Patients using [Braintree], MiraLAX [Schering-Plough]) that require NaP preparations should be carefully instructed to the addition of bisacodyl or magnesium citrate. The rec- maintain adequate fluid intake throughout the bowel ommended dosing of most PEG solutions is 240 mL (8 cleansing process and to not exceed the recommended oz) every 10 minutes. A “split-dose” regimen—in which part of the laxative is taken the evening before, and the A tablet formulation of NaP, designed to improve remainder is taken the morning of the procedure—has patient tolerability, was approved by the FDA in 2000.
been demonstrated to be more effective and better tol- Visicol (Salix), the initial formulation, was recommended erated than a single dose taken the evening before the at a dose of 48 to 60 g, or 28 to 40 tablets split between procedure (see below). It is estimated that 5% to 38% of 2 doses. Due to the presence of insoluble microcrys- patients are unable to complete the 4-L PEG prepara- talline cellulose—an insoluble excipient within the NaP tion because of volume-related symptoms of abdominal tablet that obscured visualization of colonic mucosa, in fullness, nausea, or vomiting.4 Low-volume PEG prepa- some instances—a residue-free NaP tablet was devel- rations were developed in an effort to improve patient oped. OsmoPrep (Salix) is smaller and has a smooth waxy surface that improves its ease of swallowing. The The low-volume PEG products are generally associat- recommended dosage is 32 tablets—20 tablets the ed with less abdominal discomfort, nausea, and vomiting evening before and 12 tablets 3 to 5 hours prior to exam- than the 4-L preparations, yet with equivalent efficacy.4-5 ination. Compared with Visicol, OsmoPrep induced less At the current time, most low-volume PEG preparations pronounced changes in electrolyte levels and fewer require the addition of adjunctive stimulant laxative.
adverse events, including abdominal distention, nausea, Patients ingest 4 bisacodyl delayed-release tablets (20 mg) at approximately 12 noon the day before the proce- At least 16 studies have compared the efficacy and dure, and start the lavage solution following evacuation tolerability of PEG with NaP.4 Overall, these trials or no more than 6 hours later. A low-volume PEG prepa- demonstrated that NaP is more effective than either the ration has recently been introduced that does not require 2-L or 4-L PEG-based preparations. In most of these the addition of a laxative (MoviPrep, Salix). In addition to studies, patient tolerance and compliance with bowel PEG-3350 and sodium sulfate, it contains ascorbic acid preparations was also superior with NaP. These conclu- which serves as an osmotic agent to enhance bowel sions are supported by the findings of two meta-analy- cleansing. A multicenter, randomized, single-blind study ses and an evidence-based position statement prepared found MoviPrep to be as effective as 4 L PEG.6 In anoth- by the Canadian Association of Gastroenterology.2-4 er comparative study, MoviPrep and an oral NaP-based The use of NaP is often associated with abnormalities preparation produced comparable results in overall colon in serum electrolytes, including hypernatremia, hypokalemia, hypocalcemia, and hyperphosphatemia.
Overall, the safety record with PEG-based prepara- Although these alterations are usually transient and clin- tions has been excellent. During the 6-year period end- ically asymptomatic, the FDA received 34 reports of ing in 2002, the FDA received 100 reports of adverse adverse events between 1997 and 2002, including 18 events with PEG solutions, including 30 serious and 6 serious events and 8 fatalities related to the use of NaP fatal events.4 Complications of PEG preparations include preparations.4 A recent study reported 21 cases of acute hypothermia, hyponatremia, intestinal perforation, aspi- phosphate nephropathy, all occurring in patients that ration, and Mallory-Weiss tear.8 The use of PEG-based had recently taken a NaP bowel preparation.11 Seventeen bowel cleansing is contraindicated in patients with patients (81%) were female, the mean age among I N D E P E N D E N T LY D E V E L O P E D B Y M C M A H O N P U B L I S H I N G Table. Commonly Used Purgatives for Colonoscopy Preparation
Recommended Usage*
Sodium Phosphate
colonoscopy; 45 mL 10 to 12 h later (at least 3 h before the procedure) colonoscopy; 30 mL 10 to 12 h later (at least 3 h before the procedure) 20 tablets (3 tablets every 15 min) at 5 to 6 pmthe evening before colonoscopy; repeat with 12 to 20 tablets 10 to 12 h later (at least 3 hbefore the procedure) 20 tablets (4 tablets every 15 min) at 5 to 6 pmthe evening before colonoscopy; repeat with 12 tablets 10 to 12 h later (at least 3 h before the procedure) Polyethylene glycol
4-L PEG-ELS
240 mL (8 oz) every 10 min beginning at 5 to 6 pm the evening before colonoscopy(total, 3 L); remaining 1 L 10 to 12 h later (at least 3 h before the procedure) 4-L SF-PEG
2-L PEG-ELS and bisacodyl
4 bisacodyl delayed-release tablets at 12 noon delayed-release tablets
the day before colonoscopy; 240 mL (8 oz)every 10 min beginning at 5 to 6 pm (total, 1 L);repeat 240 mL (8 oz) every 10 min beginning 3 to 4 h before the procedure (total, 1 L) 2-L PEG and bisacodyl
delayed-release tablets
2-L PEG with ascorbate
240 mL (8 oz) every 15 min beginning at 5 to 6 pm the evening before colonoscopy(total, 1 L), followed by at least 16 oz fluid; 240mL (8 oz) every 15 min at least 3 to 4 h beforethe procedure (total, 1 L), followed by 16 oz fluid Magnesium citrate
magnesium citrate (pre-measured quantity) at 5 to 6 pm the evening before colonoscopy; 4 bisacodyl delayed-release tablets at 7 to 8 pm (2 h after magnesium citrate); bisacodyl suppository 2 to 3 h before the procedure ELS, electrolyte lavage solution; h, hours; L, liters; min, minutes; mL, milliliters; oz, ounces; PEG, polyethylene glycol; SF, sulfate-free
* In some cases, these recommendations do not correspond with the FDA-approved dosage.
I N D E P E N D E N T LY D E V E L O P E D B Y M C M A H O N P U B L I S H I N G patients was 64 years, 16 of the 21 (76%) had a history eliminating the need to discuss with the patient more of hypertension, and 14 (67%) were taking an than one regimen of bowel cleansing. Among the disad- angiotensin-converting enzyme inhibitor or angiotensin vantages, however, is an inability to adjust for differ- receptor blocker. Although the exact incidence of this ences between patients. For example, individuals vary in complication cannot accurately be quantified, the risk their tolerance and reaction to purgatives.14 The same appears to be quite low considering the relatively small cathartic may be well tolerated by one patient but pro- number of cases reported and the extraordinarily large duce nausea, vomiting, and abdominal cramps in anoth- number of exposures to NaP (estimated to be in excess er. Some patients prefer NaP pills whereas others favor of 5,000,000 per year).12 On the basis of its overall safe- the solution. Individuals with chronic constipation may ty and efficacy, NaP is an appropriate option for bowel require a more rigorous bowel cleansing regimen for preparation in healthy individuals not possessing one of adequate bowel cleansing. Differences such as these are best accommodated by offering several bowel prepara-tions, so that each patient can be matched with the preparation that is most likely to be effective, safe, and Magnesium citrate is a hyperosmotic saline laxative that increases intraluminal fluid volume, and, via stimu- When endoscopy is performed in an open access set- lation of cholecystokinin release, enhances gut motility.
ting, it is necessary to prescreen patients before select- It is administered as a split dose, 300 mL (10 oz) the ing a purgative regimen. In our practice, a receptionist evening before colonoscopy and 3 to 5 hours prior to or medical assistant completes a brief medical question- the procedure. Since magnesium is eliminated by the naire for each patient at the time of scheduling.
kidneys, it should not be used in patients with renal dis- Information obtained that pertains to the choice of purgative regimen includes: 1) a list of current medica- A prepackaged low-fiber diet (NutraPrep [E-Z-EM]) tions and drug/food allergies; 2) a history of heart fail- has recently been introduced, containing three low- ure, kidney disease, ascites, or fluid/electrolyte abnor- residue meals and snacks. The product is intended for malities; and 3) a history of chronic constipation or use in combination with a bowel cleansing system that incomplete colonoscopy. Based upon the responses, a contains a low-sodium magnesium citrate, bisacodyl- bowel cleansing regimen (NaP versus PEG) is then sug- delayed release tablets, and a bisacodyl suppository gested. If oral NaP is chosen, patients are given the (10 mg; LoSo Prep [E-Z-EM]). Patients are instructed option of solution or pill formulation. When using a PEG- to take magnesium citrate and 4 bisacodyl tablets (20 based regimen, the 2-L PEG preparation is chosen, mg) the evening before colonoscopy plus a bisacodyl except for use in patients with chronic constipation (see suppository on the morning of the procedure. A ran- below). In this way, the method of bowel cleansing for domized, investigator-blinded study reported superior colonoscopy is selected individually in order to maxi- bowel cleansing and patient tolerability with this regi- mize safety, efficacy, and patient satisfaction. Clinical Considerations
Many endoscopy centers utilize a patient education An effective preparation for colonoscopy is one that program when preparing patients for gastrointestinal consistently produces high quality bowel cleansing that endoscopy. The topics to be covered include a descrip- is adequate for the detection of all adenomatous polyps.
tion of the procedure, possible adverse effects and com- It must also be safe, and ideally, work quickly, without plications, and preparation instruction. The impact of producing gastrointestinal distress. None of the prod- bowel preparation on the success of colonoscopy, and ucts currently marketed for colonoscopy preparation the importance of compliance with instructions should meet all of these criteria. Although most are effective be emphasized. This message may be communicated when properly administered, they require 12 to 24 hours through one-on-one sessions, group meetings, or self- for adequate bowel cleansing, and a significant propor- instruction using either a videotape or computer-based tion of patients experience disturbing gastrointestinal program. Communicating this information effectively to side effects. Consequently, the choice of a purgative the patient helps to alleviate fear and anxiety related to regimen(s) and methods of administration vary consid- the procedure. In a prospective study, an education pro- erably among endoscopists. This section examines gram reduced the rate of failed preparations among strategies of colon cleansing and provides suggestions ambulatory patients from 26% to 5%.15 A role for educa- for improving the quality and safety of bowel prepara- tional intervention in hospitalized patients has not yet tion. Recommendations for colonoscopy preparation within special patient populations is also presented. BOWEL PREPARATION: ONE SIZE DOES NOT FIT ALL Colon cleansing produces significant volume loss Some endoscopists prefer to offer all patients a sin- through the gastrointestinal tract that can result in gle method of bowel preparation. The benefits of such intravascular volume depletion. The fluid loss during an approach include simplicity and an economy of time, bowel preparation may exceed 2 to 3 L, based upon an I N D E P E N D E N T LY D E V E L O P E D B Y M C M A H O N P U B L I S H I N G assessment of hemodynamic parameters and indirectmeasures such as body weight, serum osmolality andhematocrit.17 between NaP and PEG formulations have been reportedin some studies.18-21 Decreases in systolic blood pressure(> 10 mm Hg from baseline) and/or postural tachycardia(> 10 beats/minute from baseline) have been described in 10% to 35% of patients who completed a bowelcleansing regimen.18 In addition, the use of NaP prepara- Figure 1. Images of the cecum during
tions is often associated with changes in serum elec-trolytes, including transient increases in phosphate and colonoscopy demonstrate incomplete
sodium, and reductions in calcium and potassium. These versus complete bowel cleansing.
changes generally remain within the normal range and Image A demonstrates the cecum partially obscured by a thinlayer of ileal fluid and chyme. In contrast, the cecum in image B are clinically asymptomatic. Serious electrolyte distur- is optimally prepared for careful inspection of the mucosa.
bances, however, have been reported with both NaP22and PEG.23 Inadequate hydration is widely believed toplay an important role in such complications. Therefore,adequate hydration during bowel preparation should beemphasized, particularly in high-risk individuals, such asthe elderly, users of diuretics or other medications thatalter electrolyte levels, and patients with preexistingelectrolyte abnormalities. Patients should be advised toconsume at least 64 oz (approximately 2 L) of clear fluid on the day prior to colonoscopy. The use of a carbohy-drate-electrolyte solution (e.g. Gatorade) has been Figure 2. Typical images obtained
reported to improve patient hydration status, patient during colonoscopy with successful
tolerance for the preparation, and the quality of bowel bowel cleansing.
preparation.24 Patients should also be reminded to con- Image A shows multiple, punctate red spots with central clear- tinue hydration after colonoscopy; we advise that ing—a diagnostic artifact of bowel preparation. These changes patients consume at least 32 oz (4, 8-oz glasses) during are readily distinguishable from active colitis (B), which is char- the 8 hours following completion of the procedure.25 acterized by a diffuse inflammatory process.
The quality of colon preparation—especially in the ascending colon—is closely related to the time between including 1 of the doses taken the morning of the proce- completion of the preparation and the examination.20,26 dure (8 pm and 6 am).29 Patients who received part of Despite diet restriction for 24 hours, optimal cleansing their preparation on the same day had better scores for of the colon requires that at least part of the preparation quality of cleansing than those who underwent prepara- be ingested within 6 to 8 hours of the examination.
tion on the previous day (global rating good/excellent, When more than 8 hours has elapsed, ileal contents 80% vs 68%, respectively). These and other studies pro- begin to fill the colon, coating the wall of the ascending vide convincing evidence that a split-dose regimen, colon with a thin film of chyme that obscures mucosal including 1 dose of laxative within 6 to 8 hours of exam- ination, improves cleansing and imaging of the mucosa, Split-dose regimens improve the efficacy of both NaP especially within the right colon where flat polyps are and PEG preparations. In a study using 3-L PEG plus bisacodyl, a split-dose regimen (including 1 L on the day For the purpose of studying the success of bowel of procedure) gave a higher proportion of satisfactory preparation, it is helpful to distinguish patients that are preps (75% vs 66%) and better patient compliance with scheduled for morning versus afternoon procedures.
lower rates of discontinuation.27 In another study, the Patients undergoing a morning procedure should ingest quality of bowel prep was compared using 2-L PEG the first dose of cathartic between 4 and 6 pm and the preparation administered either the day of (6 to 8 h remainder between 3 and 5 am (depending on the time before) or the evening before (13 to 16 h before) the pro- of the procedure and the laxative selected). Patients cedure.28 Colon preparation was better (93% vs 72%) scheduled for afternoon procedures take their first dose and more lesions were detected (2.8 vs 1.9) in the group at 6 to 7 pm and the second dose at 6 to 7 am. Some who received same-day bowel cleansing compared with endoscopy units have modified their endoscopy sched- the group who received cleansing the evening before ule, booking all colonoscopies beginning at 12 noon. This examination, respectively. A randomized trial compared affords patients the convenience of taking the second 2 dosing regimens of NaP, 1 consisting of 2, 45-mL doses dose of laxative at 6 to 7 am, rather than waking at 3 to taken the evening before (3 pm and 8 pm) and the other 5 am. However, a recent study comparing the outcomes I N D E P E N D E N T LY D E V E L O P E D B Y M C M A H O N P U B L I S H I N G of morning versus afternoon colonoscopies reported studies. A randomized controlled trial in octogenarians significantly higher rates of incomplete procedures and compared NaP with a 4-L PEG preparation.35 The quali- lower rates of adequate bowel preparations in the after- ty of preparation was similar in both groups, with a noon.30 In our experience, many patients prefer to good or excellent rating in 77% to 81% of patients undergo colonoscopy in the morning, and most do not receiving NaP or PEG. As anticipated, PEG produced object to waking during the night to complete the less change than NaP in the clinical parameters of dehy- dration and laboratory tests. Fewer patients were In Japan, the concept of split dosing has been taken unable to complete the NaP preparation compared with one step further with colon cleansing performed entire- the PEG preparation, although the difference did not ly on the morning of examination.31 Little or no diet reach statistical significance. Overall, patients preferred modification is required the day prior to colonoscopy.
NaP to PEG and were more willing to repeat this prepa- Patients are instructed to begin the preparation around ration again in the future. A second study, comparing 6 am with 2-3 L PEG. The preparation is considered NaP with PEG in elderly patients reported that the over- complete, usually within 3 hours, when the rectal efflu- all quality of colon cleansing was comparable for both ent is clear. Anecdotally, this preparation is reported to preparations.36 Furthermore, patients who received produce excellent cleansing. It remains to be established NaP tolerated their preparation better than those who whether a similar method of preparation would be received PEG, although the difference was not statisti- effective and tolerated by Western patients. In some instances, the timing of bowel preparation Patients With Inflammatory Bowel Disease. In gener- may need to be altered in order to accommodate the al, patients with inflammatory bowel disease can pre- fasting requirements related to procedural sedation.
pare for colonoscopy using any of the standard bowel There are no universally accepted guidelines on prepro- purgatives. One exception is the patient with moderate cedural fasting, and consequently, the literature contains to severe diarrhea (more than 6 to 8 bowel movements a variety of recommendations on this subject.
per day); for this patient, the dose of cathartic may be Guidelines published by the American Society of reduced or eliminated altogether. NaP preparations can Anesthesiology state that patients should fast for a min- produce aphthoid lesions in the colon, most prominent- imum of 2 hours for clear liquids and 6 hours for light ly within the rectum and sigmoid. This endoscopic meal prior to sedation.32 On the other hand, an evi- appearance is distinct and can be readily distinguished dence-based review by American College of from the endoscopic appearances of Crohn’s and ulcer- Emergency Physicians33 states that “recent food intake is not a contraindication for administering procedural Pediatric Patients. In older children (12 years and sedation and analgesia, but should be considered in older), oral NaP solution at a dosage of 45 mL x 2 is choosing the timing and target level of sedation.” A probably the most widely used preparation.5 When used recent position statement from the American for younger children (6 to 11 years), the dose is often reduced to 30 mL x 2. NaP is not recommended for chil- “there is inadequate evidence to permit the develop- dren ages 5 years and younger. A second method of ment of absolute requirements for preprocedural fast- preparation for children is a PEG-based formulation ing, and the clinician should be guided by the practice (MiraLAX) administered at a dose of 1.25-1.5 g/kg daily parameters provided by various professional societies.” for 4 days. In some instances, a laxative, such as At the current time, until definitive evidence-based bisacodyl, may be added to the regimen 1 day prior to guidance is available, it is reasonable to recommend that colonoscopy. The least commonly used preparation patients undergoing colonoscopy with sedation remain consists of either saline or phosphate enemas in combi- fasting for a minimum of 2 hours before the procedure.
This requirement does not necessitate a change in the In the pediatric population, there are inadequate data use of a split-dose regimen for bowel preparation. assessing efficacy and safety to recommend 1 regimenover another. The PEG-based preparations are generally effective, but are often accompanied by abdominal Elderly Patients. Persons 65 years and older comprise bloating and vomiting.37 A modified PEG preparation at least 20% of the patient population undergoing rou- that is administered over 4 days appears to be better tine colonoscopy. Older individuals are more likely to tolerated, but has the potential for disrupting a child’s have an incomplete preparation.1,35 The reasons for this ability to attend school and participate in other activi- are multifactorial and include an increased likelihood for ties.38 Generally, oral NaP is better tolerated by children constipation, reduced mobility, and difficulty complet- than PEG, although hyperphosphatemia is often ing the preparation. Elderly patients using NaP are also observed. Practice recommendations for bowel prepa- more likely to manifest hyperphosphatemia as a result ration in children undergoing colonoscopy vary. A of impaired renal function, co-morbid illness, and con- recent consensus statement prepared by a joint task force within the United States5 concluded that NaP, PEG, The efficacy, safety, and tolerability of various purga- and phosphate enema/senna preparations were all “safe tives in older individuals have been evaluated in several and will adequately prepare the child’s colon for I N D E P E N D E N T LY D E V E L O P E D B Y M C M A H O N P U B L I S H I N G colonoscopy.” The authors caution, however, that “incertain circumstances, such as bowel preparation in chil- Box. Key Points
dren, … it may be advisable to adhere to PEG-basedsolutions because of the risks for occult physiologic dis- 1. The choice of bowel cleansing regimen for turbances that may potentially contraindicate the use of colonoscopy should be based upon the patient’s NaP-based regimens.” For example, the FDA-approved age, health status, comorbid diseases, and personal preference. package insert of one manufacturer of NaP (CB Fleet),cautions against the use of oral NaP “in children under 2. A split dose bowel cleansing regimen that includes 1 dose of laxative within 6 to 8 hours of the age of 18 years.” Regardless of the regimen selected, the examination improves the quality of bowel it is important to provide children with adequate hydra- cleansing, especially within the ascending colon. tion during the process of bowel preparation. A carbo- hydrate-electrolyte solution designed specifically for demonstrated superior efficacy and tolerability to children is often helpful for this purpose. polyethylene glycol (PEG)-based preparations for Patients With Lower Gastrointestinal Bleeding. In colonoscopy preparation. NaP is an acceptable most circumstances, patients undergoing colonoscopy purgative for bowel cleansing in suitable patients; for hematochezia must be prepared quickly.39 Colon however, its use should be avoided in patients transit is hastened by the presence of blood, and in most with impaired renal function, congestive heart failure, advanced liver disease, and hypercalcemia. cases, bowel cleansing can be completed within 2 to 3hours using 0.5 to 2 L of PEG solution. Patients who are 4. All purgatives have been associated with serious adverse events. The risk for complications unresponsive or mechanically ventilated may receive the PEG solution through a nasogastric tube. appropriate bowel cleansing regimen for each Patients With a History of Inadequate Preparation or patient and highlighting the importance of Chronic Constipation. There are no studies to provide adherence to preparation instructions.
the clinician with guidance for preparation of the patient 5. The importance of adequate hydration during and with chronic constipation or a history of inadequate after bowel preparation should be emphasized for bowel cleansing during a previous colonoscopy.
Measures that have been recommended include: 1)extending the period of diet modification from 24 hoursto 48 hours; 2) adding oral bisacodyl or senna to a PEGor NaP regimen; and 3) increasing the total volume of colonoscopy: efficacy, tolerability and safety - A CanadianAssociation of Gastroenterology position paper. Can J PEG from 4 L to 6 L, with administration split over 48 hours (usually 1 to 2 L on day 1, and 3 to 4 L on day 2).
5. Wexner SD, Beck DE, Baron TH, et al. A consensus document on In addition, adequate hydration will help to improve the bowel preparation before colonoscopy: prepared by a task force from The American Society of Colon and Rectal Surgeons(ASCRS), the American Society for Gastrointestinal Endoscopy(ASGE), and the Society of American Gastrointestinal and Conclusion
Endoscopic Surgeons (SAGES). Gastrointest Endosc.
A substantial number of colonoscopies are subopti- 6. Ell C, Gruss H-J. Results of a randomised, multi-centre, single-blind mal because of inadequate bowel preparation. This trial to compare the efficacy, acceptability and safety of a new 2- figure ranges from 17% to 30% in randomized trials and litre gut cleansing solution versus a standard 4-litre PEG+E solu- is probably higher in clinical practice. Several patient tion. Gastrointest Endosc. 2004;59:AB125[Abstract S1555].
characteristics have been associated with poor bowel Bitoun A, Ponchon T, Barthet M, Coffin B, Dugue C, Halphen M.
Results of a prospective randomised multicentre controlled trial preparation, including history of constipation, inpa- comparing a new 2-L ascorbic acid plus polyethylene glycol and tient status, use of antidepressants, and noncompli- electrolyte solution vs. sodium phosphate solution in patients ance with bowel preparation instructions.40,41 An undergoing elective colonoscopy. Aliment Pharmacol Ther.
2006;24:1631-1642.
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AUTHOR DISCLOSURES—Dr. Cohen has served on the advisory board and speakers’ bureau of Salix Pharmaceuticals. Dr. Tennyson has DISCLAIMER—This review is designed to be a summary of information, and represents the opinions of the author. Although detailed, the review is not exhaustive. Readers are strongly urged to consult any relevant primary literature, the complete prescribing informa- tion available in the package insert of each drug, and the appropriate clinical protocols. No liability will be assumed for the use of this review, and the absence of typographical errors is not guaranteed. Copyright 2007, McMahon Publishing, 545 West 45th Street, 8th Floor, New York, NY 10036. Printed in the USA. All rights reserved, including right of reproduction, in whole or in part, in any form.
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Patient Guide to PREPARING FOR COLONOSCOPY reparing for colonoscopy involves cleaning your bowel completely so that your physician has a clear view during the exam. This process is very important because if everything Phas not been removed from your intestines, the procedure could take longer, there is a greater risk for complications, the physician may not be able to finish the colonoscopy prop- erly, and you might have to do it all over again sooner than normal. To ensure that your colonoscopy is completed properly, follow all your doctor’s instructions.
Helpful Tips
There are different methods to clean out your colon, and your doctor will tailor one for you that he or she has found works. To make sure you and your doctor choose the right method for you, tell your doctor of your current medications, any drug or food allergies, and if you have ever had heart problems, kidney disease, ascites, fluid or electrolyte abnormalities, chronic constipation, or an incomplete colonoscopy. Remember to follow your doctor’s instructions exactly so your procedure is completed as smoothly as possible.
Why do I have to drink so much fluid for the colonoscopy? You may be given liquid electrolytes or something similar to drink before your colonoscopy.
It will be a lot to drink and it may not taste very good; but, it is important to drink the entire preparation to thoroughly clean your colon, avoiding any problems during the procedure and making sure you do not have to do it again any time soon.
Why do I have to eat and drink differently? Your doctor may give you a list of low-fiber foods to eat for one to three days before your colonoscopy. Make sure to stick to eating foods on this list as much as possible. Your doctor will also ask you not to eat anything after a certain time before your test and to drink plenty of clear, nonalcoholic fluids. Doing so will make cleaning your colon more complete, as well as keep you hydrated and safe from any problems with the preparation for the colonoscopy and the colonoscopy itself.
RESOURCES
www.mayoclinic.com/health/colonoscopy/CO00009
Centers for Disease Control and Prevention www.cdc.gov/cancer/colorectal/basic_info/screening
www.gastro.org/wmspage.cfm?parm1=861

Source: http://www.gastroenterologistnewyork.com/webdocuments/pubs-bowel-preperation-for-colonoscopy.pdf