Bowel preparation: comparing metabolic and electrolyte changes when using sodium phosphate/polyethylene glycol.

Background: Many patients with various types of colonic pathology undergo invasive procedures that require mechanical bowel preparation. The most commonly used medications for bowel preparation include phosphate-containing drugs which are low cost and enable this procedure to be performed in an outpatient setting, as opposed to other medications, such as polyethylene glycol. Recent studies have suggested that freely using phosphate-containing drugs might lead to renal function impairment in a small group of patients. Despite this, many surgeons still use these drugs to prepare their patients. We conducted a comparative study to check the side effects of phosphate-containing drugs compared to polyethylene glycol when used for bowel cleansing.

Methods: We conducted a double blind prospective randomized study that included 40 patients undergoing surgery for colonic pathology, all of whom underwent bowel cleansing (20 with sodium phosphate and 20 with polyethylene glycol). During the perioperative course, electrolyte parameters were collected from serum and urine and compared between the two groups of patients.

Results: Changes in electrolyte and metabolic parameters were shown in both groups, but more prominently in patients prepared with sodium phosphate. In addition, early signs of renal function impairment appeared in this group. The differences in metabolic and electrolyte changes between the two groups were statistically significant.

Conclusions: On the basis of this study, we propose that the wide use of phosphate-containing drugs for colonic preparation might be dangerous for the specific group of patients that is prone to develop renal failure or electrolyte abnormalities.