Clinicians can use a range of methods and efficacies to prepare the bowel for colonoscopy. Colonoscopy is currently the gold standard for imaging the mucosa of the colon to identify any concerning lesions for excision or biopsy. Reviews have shown that rates of incomplete colonoscopies, defined as the inability to achieve cecal intubation and mucosal visualization effectively has ranged between 10% to 20%. Poor bowel preparation can lead to failed detection of cancerous lesions and has been associated with an increased risk of procedural adverse events.
Many studies have identified risk factors for poor bowel preparation. These risk factors include previous poor bowel preparation, non-English speaking, Medicaid insurance, single, inpatient status, polypharmacy, suffering from obesity, advanced age, male gender, and comorbidities such as diabetes, stroke, dementia, and Parkinson disease. Ideal preparation reduces patient discomfort and reduces shifts in fluid and electrolytes. Preparation should be safe, tolerable, and inexpensive.
Adequate bowel preparation increases the likelihood of identifying lesions during colonoscopy. Colonoscopies are intended to examine the rectum, colon (sigmoid colon, descending colon, transverse colon, ascending colon, and the cecum) and the distal part of the small intestine, the terminal ileum.
Adequate bowel preparation is indicated when a colonoscopy is needed.
There are certain contraindications to specific bowel preparations which include but are not limited to:
The primary care physician or gastroenterologist determines the most appropriate bowel preparation for a patient. Often, the decision can be collaborative because the primary care physician may have greater knowledge regarding medical history that may contraindicate certain bowel regimens. The gastroenterologist is most likely to decide on care because they have more, in-depth knowledge about bowel regimens and can educate and instruct the patient on how to properly administer the regimen. In the inpatient setting, the nursing staff plays a pivotal role in monitoring the patient for complaints, side effects, and ensuring complete and proper administration of the regimen.
Bowel preparation can be divided into 3 categories: isosmotic, hyposmotic, and hyperosmotic agents.
Isosmotic agents include high-volume polyethylene glycol (PEG) preparations, low-volume PEG preparations, and sulfate-free PEG-electrolyte solutions (ELS).
Hyposmotic agents include a low-volume PEG preparation called PEG-3350 (PEG-SD) that requires an additional electrolyte solution (sports drink) and often combined with bisacodyl. The combination of PEG-3350 and an electrolyte solution is not FDA approved for bowel preparation prior to colonoscopy and is not considered equivalent to the isomotic, low-volume, 2-L, PEG-ELS. There have been numerous studies that have found mixed results regarding colonic cleaning, and electrolyte abnormalities such changes in sodium, potassium, and clorine(Cl). Some studies have shown that PEG-3350 is more likely to cause electrolyte abnormalities such as hyponatremia than low-volume, 2-L, PEG-ELS.
Hyperosmotic agents include magnesium citrate, oral sodium sulfate, and sodium phosphate.
There are also combination agents such as sodium picosulfate/magnesium citrate and sodium sulfate/sulfate-free PEG-ELS that have been used for bowel preparation.
The Boston Bowel Preparation Scale (BBPS) was developed to assess bowel preparation after all cleaning maneuvers. Each segment of the colon, the right colon, transverse colon, and left colon are assigned points from 0 to 3 with regards to the cleanliness of the colon. A score of 0 includes an unprepared colon, 1 includes those in which only a portion of the mucosa of the colon segment is visible, 2 includes those with a minor amount of residual staining and small fragments of stool present, and lastly, 3 includes those where the entire mucosa of the colon is seen well with no residual stool. Each segment of the colon is assigned a score, and the entire colon is assigned a cumulative score. Higher scores indicate better a preparation.
Bowel preparation can be given in a single dose or a split dose. A higher quality bowel preparation and increased adenoma detection rate has been demonstrated in those taking a split dosed bowel preparation. Typically, the first dose should be taken the day before the procedure and the second dose is taken 3 to 8 hours before the start of the colonoscopy.
Poor bowel preparation can be a potentially severe limitation on the usefulness of colonoscopies. Proper bowel preparation leads to clean identifiable mucosa, and as a result, there is a greater ability to detect polyps and other lesions. Contrary, poor bowel preparation can potentially cause missed identification of lesions or polyps that can have morbidity and mortality effects on the individual.
Interprofessional care for a patient undergoing bowel preparation is vital to ensure better preparation and colonoscopy outcomes. An interprofessional team consists of a primary care physician, gastroenterologist, nurses, and a pharmacist. With a team-based approach, a proper bowel preparation regimen can be selected based on the patient's medical history and potential side effects. A single dose versus a split dose regimen can be selected to accommodate the patient's lifestyle.
One study found that the utility of telephone re-education about bowel preparation the day before a colonoscopy significantly improved the quality of bowel preparation and the rate of polyp detection. (Level I)