Does bowel preparation improve the quality of intravenous urography?

Many radiology departments continue to use bowel preparation prior to intravenous urography (IVU) despite recent studies questioning its value. This prospective study was designed to test the hypothesis that bowel preparation does not affect the quality of IVU, the number of films taken, or the use of tomography. 144 patients were randomized into three groups; 49 had no preparation, 48 received a mild stimulant laxative (Dulcolax), and 47 took an osmotic laxative (Citramag). The subsequent IVUs were then reviewed by two observers; the control and contrast films were scored for the presence of faecal residue, and the visibility of the renal tract, respectively. Patients were also questioned about the side effects of the two preparations. There was no significant difference in the scores for renal tract visibility in those patients receiving stimulant laxative when compared with the unprepared group. Those receiving the osmotic laxative had significantly less faecal residue but this was at the expense of an increased amount of bowel gas. The osmotic laxative group had significantly higher scores, indicating better visualization of the urinary tract, than the other groups, but no significant reduction in the number of radiographs taken or the use of tomography. This group also reported more side effects. Overall our results suggest that the routine use of a laxative prior to an IVU examination does not decrease the radiation dose and produces some patient inconvenience. The practice therefore cannot be routinely recommended.