Bowel Preparation of Outpatients for Intravenous Urography: Efficacy of Castor Oil Versus Bisacodyl

The purpose of this study was to compare the efficacy of two laxatives, castor oil and bisacodyl, in the routine bowel preparation of outpatients for intravenous urography (IVU). We used castor oil in patients undergoing IVU for 1 month, and then used bisacodyl in patients undergoing IVU for another month. Two uroradiologists, unaware of the method of bowel preparation, reviewed the standard radiographs and graded the residue in the large bowel and the clearness of the opacified urinary collecting system. In total, 71 consecutive outpatients received castor oil, and 84 received bisacodyl. For the castor oil group, grades from the two uroradiologists did not differ in terms of fecal residue on plain abdominal images (p = 0.54), and visualization of the urinary system on the left (p = 0.36) and right sides (p = 0.63). Findings were similar for bisacodyl recipients (p = 0.11, 0.59, and 0.32, respectively). When the laxative effect of the two agents was compared, we found no difference in the grading of fecal residue on plain abdominal images (p = 0.14), or in visualization of the urinary system on the left (p = 0.31) and right sides (p = 0.98). In conclusion, we observed no difference in laxative efficacy between castor oil and bisacodyl; thus, bisacodyl may be a useful alternative for bowel preparation before IVU.