Poor Colonoscopy Preparation Linked to High Miss Rates

A new study has found that suboptimal bowel preparation is associated with a substantially lower efficacy of colonoscopy to detect adenomas, suggesting the need for an early follow-up examination.

Researchers at Columbia University Medical Center (CUMC; New York, NY, USA) conducted a retrospective study to identify factors associated with the decision to repeat an examination early after a colonoscopy done with suboptimal bowel preparation, and to quantify adenoma miss rates among those pairs of colonoscopies separated by an interval shorter than the time suggested by current guidelines. The researchers also recorded the quality of bowel preparation in 12,787 patients undergoing colonoscopy. Patients who had early subsequent colonoscopy were also more likely to have lack of cecal intubation on the first procedure, and to have had a polyp found on the first procedure.

The results showed that of the 3,047 patients (24%) in whom preparation quality was poor or fair, 505 patients (17%) underwent subsequent colonoscopy in less than 3 years; on the subsequent colonoscopy, 216 of 505 patients had optimal preparation. In these patients, of 198 adenomas identified on the second procedure, 83 were not visualized on the initial procedure. This finding yielded an adenoma miss rate of 42% overall, with an advanced adenoma miss rate of 27%. When colonoscopy was repeated in less than one year, the adenoma miss rate was 35% overall, and 36% for advanced adenomas. The study was published in the June 2011 issue of Gastrointestinal Endoscopy.

“Although a minority of patients undergo early repeat examination after colonoscopies done with suboptimal bowel preparation, the miss rates for colonoscopies done with suboptimal bowel preparation were high,” said lead author Benjamin Lebwohl, MD, MS. “Because neoplastic findings on the initial colonoscopy were associated with a greater miss rate, a repeat examination within one year is indicated when an adenoma is found during a colonoscopy with suboptimal bowel preparation.”

Adequate colon preparation involves a detailed cleaning regimen using a combination of diet and colonoscopy cleansing preparations. In general, this consists of drinking a large volume of a special cleansing solution, a clear liquid diet for several days, and laxatives or enemas prior to the examination. Both oral sodium phosphate (NaP) and polyethylene glycol-based lavage (PEG-ELS) are used predominantly as bowel cleansing modalities.

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