High-dose bisacodyl plus water lavage compared with oral sodium phosphate as bowel preparation for outpatient colonoscopy.

Background: The aim of this prospective study was to compare the efficacy and patient compliance of an oral high dose of bisacodyl plus water lavage and oral sodium phosphate in adults undergoing elective colonoscopy.

Methods: A total of 276 patients were randomized to receive an oral high-dose bisacodyl preparation (6 tablets of 5mg bisacodyl) plus water lavage (2 L of water) or an oral sodium phosphate (NaP) preparation (90 mL in divided doses). All endoscopic procedures were conducted in the afternoon. The endoscopist was blinded to the preparation the patient had received and graded the quality of colon cleansing as excellent, good, fair, poor, or failed. Patients' demographic data, indications for the procedure, and colonoscopic findings were recorded and compared.

Results: Significantly improved (p < 0.001) bowel preparation after NaP compared with bisacodyl plus water lavage was reported. The completion rate of colonoscopy was significantly lower (p < 0.001) in the bisacodyl group (70.6%) than in the NaP group (92.9%). The detection of polyps was significantly increased (p = 0.017) in the NaP group (43.1%) compared with the bisacodyl group (27.1%). A procedural indication of constipation was an independent predictor of failed preparation in the bisacodyl group (odds ratio, 4.8; 95% confidence interval, 1.9-12.0; p < 0.001).

Conclusion: The quality of bowel preparation with oral NaP was better than that with bisacodyl plus water lavage.