Randomized Trial Comparing the Safety and Clarity of Water Versus Saline Irrigant In Ureteroscopy

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Risks of using sterile water irrigant in endoscopic procedures include development of hyponatremia and transurethral resection syndrome. For these concerns, AUA stone treatment guidelines recommend use of 0.9% saline in ureteroscopy (URS). However, water may provide better visualization, and a prospective study has indicated that fluid absorption in URS is minimal. We hypothesize that water irrigant will not significantly change serum sodium and osmolality compared to saline and that water will provide better visualization in URS.


In 2017, 106 adult patients undergoing URS were prospectively randomized to receive sterile water or 0.9% saline irrigant. Patients and surgeons were blinded to fluid type. Pulsed irrigation was used. Serum sodium and osmolality were assessed before and after surgery. Fluid clarity was measured subjectively by surgeon scores and objectively by turbidity analysis with a turbidimeter of renal fluid collected in surgery. A p-value


106 patients (mean age 56 years) underwent URS (mean time 35 min) with median irrigation volume of 598 mL (IQR 349-1106). For the 87 (82%) patients who had URS for nephrolithiasis, median stone number was 1, and mean stone burden was 13 mm. There were no significant differences in demographic, clinical, and intraoperative variables between water and saline groups, except higher BMI in the saline group (p=0.0023). The difference in mean change in serum sodium between water and saline groups was statistically significant but not clinically meaningful (-0.46 ± 2.09 vs. 0.52 ± 2.25, p=0.022) (Table 1). Difference in change in osmolality was not significant. Of note, the water group had fewer postoperative hyponatremia (serum Na ≤135 mEq/L) events (2) than the saline group (4). Median surgeon visualization score was significantly higher for the water group (p=0.001). Measured turbidity was significantly lower for the water group (p=0.027).


Water irrigant does not cause clinically significant changes in serum sodium and osmolality or increase risk of hyponatremia compared to saline in URS. Water also appears to give clearer endoscopic visualization. Thus, water irrigant is safe in uncomplicated URS and may be preferred in cases with suboptimal visualization.

Funding: none