Water rather than saline irrigation for uncomplicated ureteroscopy (URS) does not increase hyponatremia and provides clearer endoscopic visualization, according to a new study.

“The improved visualization with water irrigant offers an incentive to use water in URS and may improve efficacy and safety of URS, although this was not studied,” investigators reported in European Urology Focus. “Other incentives include higher availability of water and its low cost, relevant in resource-poor countries.”

In a prospective, double-blinded study, Kenneth Ogan, MD, of Emory University School of Medicine in Atlanta, and colleagues randomly assigned 121 undergoing URS to water irrigation (61 patients) or saline irrigation (60 patients). The patients had a median age of 56 years.

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 Among the 101 patients who had nephrolithiasis, the mean number of stones was 1.96 and the mean stone burden was 12.68 mm. Overall, mean operative time was 35 minutes and mean irrigation volume was 839 mL.

The water and saline groups did not differ significantly in rates of hyponatremia (2 vs 5 patients, none requiring treatment), hypo-osmolality (0 vs 0 patients), or hypothermia (3 vs 2 patients).

The investigators observed no differences between the groups in hemolysis or fluid overload, although they did not objectively evaluate these conditions.

With respect to adverse events, no between-group differences were observed in mortality, grade III Clavien-Dindo complications, emergency department visits, hospital admissions, or surgical reinterventions.

Water provided better visualization than saline in URS. Mean postoperative turbidity was significantly lower with water: 64 vs 144 nephelometric turbidity units. Median surgeon visualization score, based on a Likert rating scale from 1 to 5, with 1 being poor visualization and 5 being excellent visualization, also was significantly higher with water: 4 (above average) vs 3 (average).

“These appropriately powered findings suggest that water irrigant may be safe for use in uncomplicated URS procedures for the benefit of improved visualization,” Dr Ogan’s team wrote. “However, it would be prudent to have these results verified in larger studies to affirm the safety of water irrigant in URS and further characterize in which cases water may be used prior to changing practice.”

According to the investigators, saline irrigation might be preferable for lengthy or complex URS cases with ureteral perforation, children, and patients with renal failure or cardiorespiratory complications because these groups are at greater risk for fluid absorption and possibly electrolyte imbalances.

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The American Urological Association (AUA) guidelines on surgical stone management recommend saline irrigant in URS because risks associated with water irrigant have been reported in other endoscopic procedures, particularly in transurethral resection of the prostate (TURP) and, sometimes, in percutaneous nephrolithotomy (PCNL), the authors noted.

Dr Ogan’s team pointed out that their findings differ from literature demonstrating the danger of using water irrigant in other endoscopic procedures, especially TURP and, when absorption is severe, PCNL. “We attribute this difference to the inherently increased invasiveness of PCNL and TURP.”


Pirani F, Makhani SS, Kim FY, et al. Prospective randomized trial comparing the safety and clarity of water versus saline irrigant in ureteroscopy [published online March 4, 2020]. Eur Urol Focus. doi: 10.1016/j.euf.2020.02.009