Quality of bowel prep crucial for best colonoscopy outcomes

One of best ways to prevent bowel cancer is to catch it early. Colonoscopy has long been considered the gold standard for the detection of colorectal polyps, the removal of which can prevent bowel cancer from actually forming.

However, European researchers have found that the quality of bowel preparation prior to a colonoscopy is also of paramount importance to ensuring a high-quality screening with optimal results.

Using the Aronchick scale – which categorises bowel preparation as excellent, good, fair, poor or inadequate – doctors from the Medical University of Vienna studied data from more than 300,000 people aged 50 years and over who underwent screening colonoscopy over a decade (from 2012-2022).

Publishing their results in the American Journal of Gastroenterology, the researchers found that worsening degrees of bowel prep can impact the accuracy and effectiveness of the examination as it can lead to decreased rates of detecting adenoma, high-risk polyp, sessile serrated lesion (SSL) and traditional serrated adenoma (TSA), while also increasing procedure time, patient discomfort and the potential for repeat procedures.

“The risk of dying from PCCRC (post-colonoscopy colorectal cancer) was more than twofold higher with fair or poor bowel prep, and more than fourfold higher with inadequate prep,” the study authors said.

The good news is that the study found bowel preparation was excellent in 37 per cent of procedures and good in 48 per cent.

Several scales have been developed over time to quantify the extent of bowel preparation, such as the Boston Bowel Preparation Scale, the Ottawa Scale and the five-tier Aronchick Scale, to provide a minimum standard.

Adequate bowel preparation considered as either “excellent”, “good” or “fair” on the Aronchick scale.

“However, these scales are highly operator dependent, and the rating is strongly influenced by preference and experience of the endoscopists,” the authors noted.

“Our findings further support the evidence that bowel preparation is a crucial element of high-quality colonoscopy that affects bowel cancer outcomes in screening participants,” they said. “Efforts should be made to increase bowel cleansing above fair scores.”

The study also noted that patient education should focus on evidence-based measures for bowel cleansing optimisation. As such, split-dose bowel preparation with the second dose taken three to eight hours before the examination should be the preferred bowel preparation regimen.

In addition, sufficient fluid intake is essential for proper bowel cleaning, alongside dietary measures, such as consumption of a liquid diet the day before the scheduled colonoscopy.