Objective: To compare bowel preparation quality and patient tolerance of two common enema solutions for flexible sigmoidoscopy.
Material and Method: Three hundred adults were randomized to receive a hypertonic sodium chloride or hypertonic sodium phosphate enema regime, each consisting of two enemas administered 60 and 30 min before the procedure. Patients completed surveys on preparation comfort. Patients and endoscopist were blinded to the preparation used. During the procedure, the endoscopist took pictures of the mucosa and intraluminal content. All pictures were later evaluated by a single doctor who graded the quality of the preparation.
Results: There were no serious complications during or following the procedures. The preparation quality was rated as excellent or good by 76.9% of the hypertonic sodium chloride group and 72.9% of the hypertonic sodium phosphate group (p = 0.423). The hypertonic sodium chloride enema was associated with more abdominal discomfort (p = 0.018).
Conclusion: Both enemas were safe for all patients with no statistical difference between the qualities of the two bowel preparations. Both preparations performed their bowel-cleaning function well and were suitable for the preparation of patients before flexible sigmoidoscopy. The less expensive hypertonic sodium chloride solution may be an option for hospitals where budgetary considerations are important.

Keywords: Flexible sigmoidoscopy, Phosphate enema, Sodium chloride enema, Bowel preparation