Low-volume bowel preparation is inferior to standard 4 1 polyethylene glycol

Four liters or more of orally taken polyethylene glycol solution (PEG) has proved to be an effective large-bowel cleansing method prior to colonoscopy. The problem has been the large volume of fluid and its taste, which is unacceptable to some examinees. We aimed to investigate the effectiveness of 2 l PEG combined with senna compared with 4 l PEG for bowel preparation.

The design was a single-center, prospective, randomized, investigator-blinded study with parallel assignment, in the setting of the Endoscopy Unit of Umeå University Hospital. Outpatients (n = 490) scheduled for colonoscopy were enrolled. The standard-volume arm received 4 l PEG, and the low-volume arm received 36 mg senna glycosides in tablets and 2 l PEG. The cleansing result (primary endpoint) was assessed by the endoscopist using the Ottawa score. The patients rated the subjective grade of ease of taking the bowel preparation. Analysis was on an intention-to-treat basis.

There were significantly more cases with poor or inadequate bowel cleansing after the low-volume alternative with senna and 2 l PEG (22/203) compared with after 4 l PEG (8/196, p = 0.027). The low-volume alternative was better tolerated by the examinees: 119/231 rated the treatment as easy to take compared with 88/238 in the 4 l PEG arm (p = 0.001).

4 l PEG treatment is better than 36 mg senna and 2 l PEG as routine colonic cleansing before colonoscopy because of fewer failures.