The routine use of probiotics to reduce post-colonoscopy symptoms cannot be recommended on the basis of a recent clinical trial in Melbourne.

The study of 150 patients at St Vincent’s Hospital found daily probiotic supplements were no better than placebo in terms of reducing post-procedural symptoms such as abdominal discomfort or bloating that are occur in about 20% of patients undergoing colonoscopy.

There was also no significant difference between the groups in the time to return to normal bowel function.

Only a sub-group of patients with pre-procedural symptoms appeared to benefit from the 14 days of probiotic capsules containing Lactobacillus acidophilus and Bidfidobacterium lactis.

There was a significant reduction in the incidence of bloating in the fortnight following their colonoscopy for patients with symptoms before their procedure who were subsequently treated with probiotics compared to those given placebo.

The colonoscopies in the study used carbon dioxide insufflation, which has been shown to improve the tolerability of the procedure compared to air insufflation.

The study authors, led by colorectal surgeon Dr Tamara Mullaney, said it was possible that bowel prep for colonoscopy changes gastrointestinal flora and provides a mechanism for post-colonoscopy symptoms in some patients.

“It is possible that the improvement in symptoms post-procedure reflects an improvement in the baseline ‘irritable bowel syndrome’-type symptoms rather than an amelioration of those symptoms caused by the bowel preparation or procedure.”

“At this point in time, the use of probiotics cannot be advocated to reduce post-colonoscopy (with carbon dioxide) symptoms in patients with no preexisting abdominal discomfort or bloating,” they wrote.

“Based on this study and a previous study, there may be a role for the use of probiotics in the subgroup of patients reporting pre-procedural symptoms although further research is required in order to better define the relationship and optimal delivery regimen.”