New research indicates that bowel preparation for colonoscopies may temporarily disrupt the gut environment, potentially leading to increased vulnerability in patients with existing gastrointestinal conditions. The preclinical study, published in Cell Reports Medicine, used mouse models to simulate the effects of bowel preparation and found that it made the animals more susceptible to infection and inflammation.
"But with further studies in humans, we hope to understand whether there are situations in which, for specific patients, these procedures may put them at risk of disease exacerbation," the researchers stated.
The findings are particularly relevant for individuals with inflammatory bowel disease (IBD), who undergo colonoscopies more frequently than others. Colonoscopy preparation involves ingesting a laxative solution to clear intestinal contents for examination. While this is generally considered safe, some patients experience complications beyond temporary discomfort.
Earlier research from Dr. Sidhartha Sinha's lab at Stanford University and Dr. Tropini's team showed that people with IBD were more likely to be prescribed anti-inflammatory steroids after undergoing bowel preparation, suggesting a link between the procedure and post-procedure flare-ups.
In the current study, mice given polyethylene glycol (PEG)—the active ingredient in common laxatives—experienced diarrhea and a temporary loss of protective mucus lining and beneficial gut bacteria. Levels of short-chain fatty acids produced by gut bacteria also dropped, reducing the body’s natural defenses against infection and inflammation. Although most mice recovered within days, those exposed to PEG had a period during which they were more vulnerable to pathogens.
To test this vulnerability, researchers exposed both PEG-treated mice and control mice (given water) to Salmonella Typhimurium. Only the PEG group developed significant infections that spread beyond the gut.
The study also explored how these changes could affect IBD patients by using mice colonized with microorganisms from ulcerative colitis patients—a form of IBD—and inducing inflammation before administering bowel prep. Mice subjected to both treatments showed increased signs of inflammation and higher levels of harmful bacteria outside the gut compared to controls.
These results suggest that clinical studies are needed to better understand potential risks for vulnerable populations such as those with IBD. Researchers are now working with Dr. Genelle Lunken's lab at BC Children's Hospital Research Institute on surveys among people undergoing colonoscopies to gather more data about symptom exacerbation following bowel prep.
If similar effects are confirmed in humans, "We can use our model to look into ways to make bowel preparation safer for people with IBD," said Dr. Tropini. Potential strategies include adjusting laxative formulations or adding beneficial substances like gut bacteria or agents that protect the mucus lining during preparation.
