Serum electrolytes, osmolality, and cleansing quality after bowel prep for colonoscopy with a PEG solution containing ascorbic acid and electrolytes

Background The cleansing procedure with PEG 3350 + ascorbic acid (PEG + Asc; Moviprep®) requires the additional ingestion of clear liquids. We aimed to determine the effects on serum electrolytes, osmolality and cleansing quality, and in a prospective “real world” trial. Patients and methods Patients underwent a standardized split-dose bowel preparation for colonoscopy with PEG + Asc. Serum electrolytes and osmolality were measured before and after the prep procedure. The volume of prep solution (PA) and additional clear liquid (CL) was recorded. Prep quality was assessed using the Ottawa Bowel Prep Grading Scale (OBPS). The primary outcome measures were changes of serum electrolytes and osmolality during the cleansing procedure. A secondary end point was the OPBS. Results One hundred ninety-one of 219 patients entered the per protocol analysis. Prep quality was considered excellent in 57.6%, moderate in 20.9%, and insufficient in 21.5%. The number of patients with hyponatremia increased from 12 (6.3%) before to 25 (13.2%) after the prep procedure. Mean sodium concentration did not change significantly. The volume of CL correlated inversely with Na + concentration ( r = − 0.409, p < 0.01) and a worse OBPS ( r = 0.198, p < 0.01). Conclusions Bowel preparation with PEG-Asc in clinical routine is generally safe, but patients should be advised not to drink more than 2 l of clear liquid because of imminent electrolyte disturbances. Additionally, the quality of cleansing either remains unchanged or may even worsen.