Risk factors and predictive model for incidence of difficult ureter during retrograde ureteroscopic lithotripsy

Abstract

Objective Difficult ureter can be a challenge for accessing upper urinary tract during lithotripsy. In this study, we evaluated the risk factors for the incidence of difficult ureter in retrograde ureteroscopic lithotripsy. Moreover, we aimed to develop a predictive model for the incidence of difficult ureter. Methods We retrospectively reviewed consecutive retrograde ureteroscopic lithotripsies performed at our institution between 2009 and 2021. A total of 1010 renal units were evaluated: 449 units with renal stones only and 561 units with ureteral stones, with or without renal stones. Results The overall incidence of difficult ureter was 5.9%, with a higher incidence in the renal alone stone group than in the ureteral stone group (7.8% vs 4.5%, P = 0.026). Multivariate regression analysis revealed three risk factors for the incidence of difficult ureter: absence of stone history (odds ratio 5.67, 95% confidence interval 2.40–13.4, and P < 0.001), age ≤45 years (odds ratio 3.61, 95% confidence interval 2.05–6.37, and P < 0.001), and renal stone only (odds ratio 2.11, 95% confidence interval 1.22–3.64, and P = 0.008). A simple model using these three risks enabled the stratification of the incidence rate of difficult ureter, with the incidence of high‐risk cases being 12.7%. Conclusions The greatest risk factor for the incidence of difficult ureter was the absence of stone history, followed by age 45 years or younger, and having only renal stones. In high‐risk cases of difficult ureter, the possibility of secondary lithotripsy should be explained to the patients.

Editorial Comment to Risk factors and predictive model for incidence of difficult ureter during retrograde ureteroscopic lithotripsy

“…However, the definition of a “Difficult ureter” is still unclear. Also, the methodology to evaluate a “Difficult ureter” in these studies including the present author’s study are not fixed clearly 5 . The measurement should be unified.…”

Effect of retrograde intrarenal surgery on the inflammatory reaction, renal function indicators and clinical efficacy in male patients with kidney stones

“…The result suggested that, during the treatment with retrograde intrarenal surgery, the secondary damage to the kidney is avoided and the patient's renal function is protected to the maximum. Meanwhile, flexible ureteroscopy is able to reach deeper calyces, renal pelvis and other parts, thus the overall effect of lithotripsy and clearance is better [28,29]. In terms of clinical surgical indicators, the operative time and the hospital stay of the study group were shorter than that of the control group, the intraoperative blood loss and the pain scores were significantly lower than that of control group.…”

Different failure rates of insertion of 10/12-Fr ureteral access sheaths during retrograde intrarenal surgery in patients with and without stones

“…Current or past stone impaction causes ureteral dilation, which may have caused the lower failure rate of UAS insertion in the stone group. In fact, we recently reported that patients with a history of stone events are less likely to require prestenting during retrograde ureteroscopic lithotripsy [ 15 ]. Additionally, younger patients, especially those in their 10s and 20s, had a higher risk for UAS insertion failure irrespective of stone events.…”