Could senna improve the quality of colonoscopy preparation with magnesium citrate?

Inadequate cleansing of the colon has an adverse effect on procedure time, safety, completion rate and diagnostic accuracy. Until now, it has been unclear whether the combination of the stimulant laxative, senna, and the osmotic laxative, magnesium citrate, results in better cleansing outcome and is acceptable and tolerable for the patients.

This question is tested in an original paper to be published in the World Journal of Gastroenterology on April 14, 2009. This study designed by Prof. Dr Barbara Braden at the John Radcliffe Hospital in Oxford, included 342 patients who required colonoscopy.

One hundred and sixty patients received magnesium citrate alone as cleansing regimen and 182 received senna granules in addition to magnesium citrate. The efficacy of the cleansing regimen was assessed by a single, experienced colonoscopist who rated it on a 4-point scale. Each patient’s experience of the bowel preparation was recorded prior to the procedure and graded. Other outcomes that were measured include the completion rate as measured by caecal intubation and the requirement for rebooking the procedure.

They found that the combination of magnesium citrate with senna granules lead to a trend for improved completion of colonoscopy as judged by caecal intubation and a reduced need for repeat of the procedure. Eighty one percent of patients who received the combination regimen achieved adequate bowel cleansing as judged by the endoscopist, as compared to 68% in the group receiving magnesium citrate alone. This difference was significant (P = 0.004). Polyp detection rates were also superior in the group receiving combined bowel preparation (P < 0.03). Side effects were similar in the two groups, apart from abdominal cramps which occurred more often in the group taking magnesium citrate and senna (P < 0.003).

It makes sense that a stimulant laxative should add efficacy to a regimen of bowel preparation using an osmotic agent. In fact, it has been shown that the addition of a stimulant laxative to a regimen of polyethylene glycol (PEG), reduces the required volume of PEG, and improves the quality of the cleansing. The addition of senna to magnesium citrate improves the efficacy of a low volume bowel preparation regimen and, although abdominal cramps were more common in the combination group, was found to be an acceptable regimen by patients. Taking into account the improved efficacy cleansing outcome and the reduced need for repeat colonoscopy, the addition of senna has a clear advantage. Adequate bowel preparation is paramount to ensure patient safety and comfort, an acceptable standard of examination and minimal procedure times, in the face of large volumes of procedures.

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