Colonoscopy Periprocedural Care

Bowel preparation

To maximize the thoroughness and safety of colonoscopy, the colon must be completely empty before the procedure. Several options are available for precolonoscopy bowel cleansing. The most commonly used preparations are as follows:

• 1.5 oz of Fleet Phospho-Soda liquid mixed into half a glass of water, followed by a full glass of water at 3:00 PM and again at 7:00 PM on the day prior to examination
• 4 L of polyethylene glycol (PEG) solution (eg, GoLYTELY, NuLYTELY, CoLyte) administered orally over a 1- to 3-hour period on the evening prior to colonoscopy

A reduced-volume lavage regimen comprising 2 L of PEG solution plus four delayed-release 5-mg bisacodyl tablets (HalfLytely) was introduced in an effort to improve patient compliance. DiPalma et al found that this preparation was as effective as a standard 4-L PEG solution but had fewer reported adverse effects. ^[9] HalfLytely has been discontinued from the US market.

Several low-volume colon cleansing preparations are available with various options for dosage regimens (eg, evening before procedure, split dose, early morning before procedure)., Examples include sodium picosulfate/magnesium oxide/anhydrous citric acid (Clenpiq), sodium sulfate/magnesium sulfate/potassium chloride (Sutab), sodium sulfate/potassium sulfate/magnesium sulfate (Suprep), and two formulations of PEG/electrolytes/sodium ascorbate/ascorbic acid (MoviPrep, PlenVu).

The stimulant laxative activity of sodium picosulfate, coupled with the osmotic laxative activity of magnesium citrate (formed from magnesium oxide and citric acid components after mixing with water), produces a purgative effect, which, when these substances are ingested with additional fluids, produces watery diarrhea.

Approval of this preparation for use in the United States was based on data from two pivotal phase III noninferiority studies comparing it with the reduced-volume lavage regimen described above. ^{[10, 11]} In both studies, Prepopik achieved successful colon cleansing according to the Aronchick scale, demonstrating noninferiority to the comparator. Additionally, it demonstrated statistical superiority in cleansing of the colon as compared with the control preparation.

MiraLax with Gatorade is a low-volume bowel preparation regimen that has been used widely in community practice and has been reported by patients to be better tolerated than GoLYTELY. A 2012 study demonstrated that bowel preparation with MiraLax in Gatorade was as efficacious as using GoLYTELY and that split dosing was more effective than single dosing. ^[12] MiraLax was better tolerated and improved the patient experience. Given the anecdotal evidence suggesting that patients consider bowel preparation the worst part of a colonoscopy, it is possible that achieving equivalent cleansing with an easier preparation will eventually lead to better compliance with colonoscopy screening.

Visicol is a prescription laxative pill designed to cleanse the colon prior to colonoscopy. In a study by Aronchick et al, this tablet form of sodium phosphate was as effective and safe as the existing aqueous preparations. ^[13] However, like Fleet Phospho-soda, Visicol contains a high phosphate load that may not be safe for patients with kidney, heart, liver, or certain intestinal diseases.

Concerns have been raised about the risk for developing renal insufficiency after the use of oral sodium phosphate solution (Fleet Phospho-soda) or Visicol in patients without a history of underlying renal disease or a recognized contraindication to the usage of oral sodium phosphate preparation.

A trigger for these concerns was a study by Markowitz et al that identified 31 cases of nephrocalcinosis among 7349 native kidney biopsy samples processed from 2000 through 2004. ^[14] Of these patients, 21 presented with acute renal failure and had a history of recent colonoscopy preceded by bowel cleansing with oral sodium phosphate solution (Fleet Phospho-Soda) or Visicol. The average baseline creatinine was 1.0 mg/dL prior to colonoscopy.

At follow-up, four patients went on to require permanent hemodialysis, and the remaining 17 all developed chronic renal insufficiency (mean serum creatinine, 2.4 mg/dL). ^[14] The authors suggested that potential etiologic factors included inadequate hydration during colon preparation, increased patient age, a history of hypertension, and concurrent use of an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker.

Regardless of the laxative method used, it should be kept in mind that to prevent dehydration, patients must drink at least 14 8-oz glasses of water or clear beverages during the day prior to colonoscopy.

It is not uncommon for patients to report being unable to tolerate the colon-cleansing preparation, often secondary to the unpalatable taste and large volume of the preparation, the occurrence of nausea and vomiting, or the presence of abdominal cramping and bloating. If the patient reports already passing clear liquid stool, discontinuance of further preparation may be considered.

The author frequently recommends placing the PEG preparations in the refrigerator 1 day before use or adding sugar-free flavor packets (eg, Crystal Light) in an effort to improve the palatability of the PEG solution. Prepopik should not be prepared in advance or refrigerated before use. Ensuring that patients ingest the cleansing agent at a particular rate is not as critical as determining that they have ingested the entire volume of the agent to ensure evacuation.

Antibiotic prophylaxis

The 1997 American Heart Association (AHA) recommendations stated that the rate of bacteremia associated with colonoscopy is 2-5% and that the typically identified organisms are unlikely to cause endocarditis. ^[15] The rate of bacteremia does not increase with mucosal biopsy or polypectomy.

The 2007 updates to the AHA recommendations stated that there is no role for antibiotic prophylaxis to prevent infective endocarditis from colonoscopy. ^[16] In high-risk patients (eg, those with prosthetic valves, a previous history of endocarditis, complex cyanotic congenital heart disease, surgically constructed pulmonary shunts or conduits, or joint replacements), the need for antibiotic prophylaxis should be determined by the physician on an individual basis. The most commonly used preprocedure and postprocedure prophylaxis regimens are as follows:

• Ampicillin or amoxicillin, 2 g IV/IM or 1.5 g orally
• Gentamicin, 1.5 mg/kg
• Vancomycin, 1 g IV

Anesthesia

Colonoscopies are routinely performed with the use of sedative medications. Administration of sedative drugs at colonoscopy has drawbacks, including an increased rate of complications, higher cost, and longer recovery periods for patients.

Some studies have demonstrated that routine use of conscious sedation does not seem to be necessary, because some participants found the examination to be only modestly or not at all uncomfortable. However, some investigators have proposed that without conscious sedation, the rate of intubation of the cecum may decrease and the risk of missing adenomas and cancer may increase.

IV benzodiazepines have been the usual premedications used for colonoscopy, either alone or with a narcotic. Midazolam (2-5 mg) and diazepam (5-10 mg) are most commonly used. Meperidine (25-100 mg) may be added as needed. The combination of benzodiazepines and narcotics may achieve sedation more smoothly but is associated with a greater risk of respiratory depression.

Propofol, a short-acting IV sedative, has become more commonly used during colonoscopies. It provides no analgesia but leads to a deeper level of sedation with rapid onset and shorter recovery time in comparison with conventional narcotic-benzodiazepine combinations. Propofol is generally administered by an anesthesiologist present at the time of the colonoscopy. Patients must be monitored (eg, blood pressure, pulse, oxygen saturation) for the duration of the procedure, as well as observed for adverse effects of these medications.

Warfarin, aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), and iron supplements should be discontinued on the days prior to examination. Insulin should not be taken during precolonoscopy fasting. Foods to avoid on the day prior to the test include those that may be misinterpreted during examination (eg, red or purple foods, Jell-O, or drinks). Patients should drink only clear liquids (no solid foods) on the day before colonoscopy and during the night before.

Positioning

The procedure is performed with the patient in the left lateral decubitus position.