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

Background: Water irrigant is discouraged in ureteroscopy due to risks demonstrated in more invasive endoscopic procedures. However, water is not well studied in ureteroscopy and may provide better visualization than standard saline.

Objective: To determine whether water irrigant increases the risk of hyponatremia compared with saline and provides better visualization in ureteroscopy.

Design, setting, and participants: A randomized, prospective, double-blinded trial was conducted. In 2017, eligible adult ureteroscopy patients at a university hospital were recruited for the study.

Intervention: Participants randomized to water or saline irrigant in ureteroscopy.

Outcome measurements and statistical analysis: Serum sodium and osmolality, body temperature, subjective surgeon visualization, and objective turbidity clarity were analyzed. Chi-square or Fisher's exact tests for categorical variables and analysis of variance test for continuous variables were performed.

Results and limitations: A total of 121 individuals (mean age 57 ± 15 yr) underwent ureteroscopy (mean time 35 ± 18 min) with a mean irrigation volume of 839 ± 608 ml. For the 101 (83%) patients who had nephrolithiasis, the mean number of stones was 2 ± 1 and the mean stone burden was 13 ± 7 mm. There were no significant differences in demographic, clinical, and intraoperative variables between water and saline groups, except for a higher body mass index in the saline group (p = 0.01). There was no significant difference between groups in the incidence of hyponatremia, hypo-osmolality, or hypothermia. The median surgeon visualization score was significantly higher using water (p < 0.01). The mean turbidity was significantly lower with water (p = 0.02). Limitations were not objectively assessing hemolysis or fluid absorption.

Conclusions: Water irrigant does not increase the incidence of hyponatremia in uncomplicated ureteroscopy and provides clearer visualization than saline.

Patient summary: We compared safety and clarity of water and saline irrigation, which aid surgeon visualization, in ureteroscopy, which can treat kidney stones. We found that water irrigant does not reduce blood sodium levels significantly compared with saline in ureteroscopy and provides better visualization.