J Digest Endosc 2019;10:178-179 single-dose regimens. Introduction of oral phosphate and sulfate salts offered the advantage of low intake volume, low risk of gastrointestinal irritation, and less volume-related adverse events compared with other available options. Oral phosphate salts have been associated with acute phosphate nephropathy, and rarely chronic renal damage. Oral sulfate salts (OSSs) have recently been approved for precolonoscopy bowel cleansing. Because sulfate absorption from the intestinal tract is saturable, serum sulfate concentrations increase only minimally after ingestion. Excretion of OSS in the kidney is not accompanied by calcium excretion and acute phosphate nephropathy. Use of OSS has not been associated with clinical manifestations of kidney injury but clinically nonsignificant serum electrolyte disturbances. 5 Studies have shown that OSS is a safe and effective bowel cleansing agent for colonoscopy. The efficacy of OSS in cleansing the colon ranges from 82 to 98%. [6][7][8][9] Studies have shown better efficacy and comparable adverse events profile of split-dose OSS regimen compared with split-dose PEG solution regardless of dose. In a study, OSS subjects reported slightly increased gastrointestinal events (abdominal distension, pain, nausea, vomiting, or abdominal discomfort) (p = 0.009) in the single-day preparation but not in the split-dose OSS regimen. 7 Colonoscopy preparation using split-dose low-volume OSS appears to be cost-effective compared with PEG-ELS with a cost saving of $16.01 per patient per year for the OSS cohort. 10 It is worth mentioning that data are available regarding the usefulness of OSS as a bowel cleansing agent for colonoscopy; however, most of the studies were performed on outdoor patients. Data regarding the efficacy and safety of OSS in the elderly patients with or without comorbidities and hospitalized patients are very limited.In the current issue, "Oral sulfate solution versus polyethylene glycol as a single day preparation for colonoscopy: a randomized control trial" by Shah et al 11 showed superior efficacy and comparable adverse events profile of OSS compared with PEG regimen for bowel preparation for colonoscopy. However, the adequate bowel cleansing was achieved Colonoscopy is a widely used procedure which requires prior cleansing of the bowel. Optimal bowel cleansing is essential for a successful and accurate examination of the bowel. Inadequate bowel cleansing during colonoscopy can result in missed lesions, difficult and incomplete procedures, prolonged cecal intubation time, and increased risk of procedural complications. The adequacy of bowel cleansing mainly depends on the type of cleansing agents, volume of preparation, mode of administration (single dose vs. split dose, single day vs. two days), use of adjunct agents, the preparation-to-colonoscopy interval, and associated comorbidities in patients. 1,2 Other factors for adequate bowel cleansing may include low residue diet, liberal fluid intake, and proper bowel preparation instruct...