Introduction: Acute obstruction of the urinary system caused by urolithiasis is a common urological emergency that necessitates immediate action. Retrograde ureteral stent (RUS) and percutaneous nephrostomy tube (PCN) are considered the standard methods of urinary drainage. The effect of ureteral stents on ureteric peristalsis has been experimentally studied and has shown that the ureteric stent is associated with ureteric dilatation, diminished ureteric peristalsis, and impairment of stone passage. However, there is currently no evidence supporting the superiority of one of them. The study aimed to compare the probability of spontaneous stone passage and its predictors after drainage by RUS and PCN.

Methods: A total of 298 patients with obstructive urolithiasis were identified retrospectively from two tertiary centers from May 2018 to April 2019. The patients were divided into three groups: RUS (104 patients), PCN (93 patients), and spontaneous stone passage (SSP) (101 patients). The patients were followed up with a non-contrast computed tomography until the stone was passed or surgical intervention was planned. The following characteristics were assessed: age, gender, body mass index (BMI), side of the stones, location, size (total stone surface area), density, duration of followup, and rate of stone passage at final followup.

Results: The age was significantly highest in the PCN group (61 years) (p=0.003), while BMI and gender distribution were similar among groups. Stone size was larger in the PCN group than in the other two groups (p=0.0001) (Table 1). The stones were located mainly in the distal ureter in the SSP group, while in the PCN and RUS groups, the stones were significantly located in the proximal ureter (Table 1). The stones' width, length, surface area, and density were highest in the PCN group, followed by the RUS group, and lastly the SSP group, with significant differences between groups (p<0.0001). Stone passage rate was significantly higher in the PCN group (39.8%) than in the RUS group (36.5%) (p<0.0001). Length of followup was longer in the double-J stent group, followed by the PCN group, and lastly SSP group, with significant differences between groups (p<0.0001).

Conclusions: In our study, a higher stone passage rate was noticed in the PCN group, despite a larger stone size. In our experience, PCN can be used as a preferred method of urinary drainage, especially in frail patients’ group who are at higher risk of surgical intervention as urinary drainage with PCN showed a higher rate of spontaneous stone passage rate. Further clinical studies are warranted.