SPECIAL CONSIDERATIONS

Inadequate bowel preparation 

Inadequate bowel preparation for colonoscopy can result in missed lesions, canceled procedures, increased procedural time, increased costs, and a potential increase in adverse event rates. In patients with fair bowel preparations, 28% to 42% had adenomas found when the examination was repeated within 3 years, including up to 27% with advanced adenomas.It has been estimated that intraprocedural cleansing accounts for 17% of total colonoscopy procedural time. One study that examined possible causes of poor preparation found that less than 20% of patients with an inadequate colonic preparation reported a failure to adequately follow preparation instructions. The most important predictor of inadequate preparation is a previous inadequate preparation. Other independent factors that have been shown to predict inadequate colon preparation include later colonoscopy starting time, failure to follow preparation instructions, hospitalized patients, procedural indication of constipation, use of tricyclic antidepressants, male sex, and a history of cirrhosis, stroke, or dementia. Obesity may also be a predictor of a poor bowel preparation

Consideration should be given to prescribing more aggressive preparations in patients who have a history of inadequate preparation quality or medical predictors of inadequate preparation. Patients who have factors predicting a lower likelihood of following preparation instructions (such as those who are non-English speaking or cognitively impaired) should receive intensified education and/or be assigned to a dedicated patient navigator. Before the examination and administration of sedation, patients should be queried about their compliance with the preparation and the quality of their effluent. Patients with persistent brown effluent should be considered for large-volume enemas or additional oral preparation before proceeding with colonoscopy.

Patients with an inadequate colon preparation usually require a repeat examination with a more thorough attempt at colonic cleansing.There is no standardized approach to an inadequately prepared colon discovered on intubation. Several irrigation devices have been developed to permit more aggressive water instillation than can be achieved with standard irrigation pumps or syringe-based flushing. Anecdotal approaches to managing inadequate preparation during colonoscopy include instilling an enema through the colonoscope and reattempting the proceedure after the patient has evacuated the enema or allowing the patient to drink additional oral preparation and then reattempting the procedure. Both of these approaches necessitate recovery from sedation and resedation and may be affected by institutional or logistical constraints

In practice, there are highly variable recommendations regarding timing of follow-up colonoscopy when the bowel preparation is judged to be inadequate. A recent study suggested that when patients were instructed to repeat colonoscopy the following day, nearly half (47%) complied, whereas rates for repeat colonoscopy were significantly lower among patients instructed to follow up at a later interval.In one study, the adenoma and advanced adenoma miss rates were 35% and 36%, respectively, for colonoscopies repeated in less than 1 year.Although immediate repeat colonoscopy after additional or more aggressive preparation administration is the preferred approach in most patients, patients with inadequate bowel preparations should be offered repeat colonoscopy examinations at least within 1 year of the inadequate examination. A shorter interval is indicated when advanced neoplasia is discovered in an inadequately prepared colon.