Predictors and a prediction model for difficult ureter in proximal ureteral calculi patients without pre-set stents

doi:10.3877/cma.j.issn.1674-0785.2026.01.005

Abstract

Abstract:

Objective

To develop and validate a predictive model for difficult ureter (DU), defined as the failure to advance an 8/9.8 Fr semi-rigid ureteroscope (sURS) retrogradely without auxiliary measures above the iliac vessel level, in patients with proximal ureteral stones without pre-stenting.

Methods

A retrospective single-center study was conducted to include 154 patients with proximal ureteral stones from July 2023 to June 2025at the Jianhu Clinical Medical College of Yangzhou University. Patients were stratified into DU (n=44) and non-DU (n=110) groups according to the aforementioned definition. Clinical and pre-operative CT parameters were analyzed. Independent predictors were identified via univariate and multivariate logistic regression to build a predictive model, which was then internally validated using Bootstrap resampling (1000 iterations).

Results

Four independent predictors were identified: stone anteroposterior diameter (odds ratio [OR]=0.737), the ratio of hydronephrosis width at the renal hilum to minimum stone diameter (OR=1.212), the difference in renal parenchyma CT value compared to the contralateral side (OR=1.069), and the thickness of the treated kidney (OR=0.942). The developed predictive model demonstrated good discrimination (area under the curve [AUC]=0.756; 95% confidence interval: 0.677~0.835) and calibration (Hosmer-Lemeshow test, P=0.113). Bootstrap validation confirmed parameter stability, yielding an optimism-corrected AUC of 0.74.

Conclusion

The predictive model developed in this study shows robust discriminative ability and stability. It can facilitate pre-operative identification of high-risk DU patients, optimizing surgical planning (e.g., preoperative stenting) to improve procedural efficacy and safety.

Key words: Difficult ureter, Ureteroscopy, Proximal ureteral stone, Risk factors, Prediction model

Ying Ni, Tielong Zhang, Gang Wang, Yulong Gao, Shaopeng Chen, Jiaxuan Ni. Predictors and a prediction model for difficult ureter in proximal ureteral calculi patients without pre-set stents[J]. Chinese Journal of Clinicians(Electronic Edition), 2026, 20(01): 28-34.

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Figures/Tables 5

项目	非DU组（n=110）	DU组（n=44）	χ²/t/Z值	P值
性别[例（%）]			χ²=0.491	0.484
男性	71	31
女性	39	13
年龄（岁， $x ¯$ ±s）	54.21±12.59	53.52±12.26	t=0.308	0.759
BMI（kg/m²， $x ¯$ ±s）	25.38±3.48	24.59±3.68	t=1.24	0.217
侧别[例（%）]			χ²=1.899	0.168
左侧	54（49.09）	27（61.36）
右侧	56（50.91）	17（38.64）
病程少于1周[例（%）]			χ²=0.261	0.61
是	50（45.45）	22（50.00）
否	60（54.55）	22（50.00）
ESWL治疗史[例（%）]			χ²=0.647	0.421
有	21（19.09）	6（13.64）
无	89（80.91）	38（86.36）
主要结石位置[例（%）]			χ²=1.005	0.316
输尿管近端	72（65.45）	25（56.82）
髂血管分叉	38（34.55）	19（43.18）
主要结石
前后径［mm，M（P₂₅，P₇₅）］	7.55（5.96，9.27）	6.14（4.82，8.17）	Z=-3.144	0.002
左右径［mm，M（P₂₅，P₇₅）］	6.30（4.98，8.57）	5.25（3.98，6.91）	Z=-2.386	0.017
上下径（mm， $x ¯$ ±s）	13.46±6.29	10.98±5.61	t=2.283	0.024
体积［mm³，M（P₂₅，P₇₅）］	313.29（151.54，584.86）	156.21（76.62，357.67）	Z=-3.08	0.002
结石中心CT值［HU， $x ¯$ ±s］	778.75±308.74	723.86±387.07	t=0.925	0.357
肾门处积水宽度（mm， $x ¯$ ±s）	18.07±10.32	20.21±13.92	t=-1.05	0.295
积水宽度与结石最小径之比（ $x ¯$ ±s）	3.00±1.93	4.44±4.01	t=-2.276	0.027
尿外渗[例（%）]			χ²=0.011	0.916
有周边渗出与蔓延	69（62.73）	28（63.64）
无渗出	41（37.27）	16（36.36）
治疗侧肾实质CT值［HU，M（P₂₅，P₇₅）］	32.88（30.00，38.48）	35.49（32.60，37.78）	Z=-1.334	0.182
治疗侧肾厚径（mm， $x ¯$ ±s）	61.50±11.13	56.91±8.88	t=2.44	0.016
与对侧比较的
肾实质CT值差［HU， $x ¯$ ±s］	-3.53±6.91	-1.20±5.75	t=-1.975	0.05
肾厚径差（mm， $x ¯$ ±s）	7.38±11.81	3.42±10.53	t=1.939	0.054

项目	非DU组（n=110）	DU组（n=44）	χ²/t/Z值	P值
性别[例（%）]			χ²=0.491	0.484
男性	71	31
女性	39	13
年龄（岁， $x ¯$ ±s）	54.21±12.59	53.52±12.26	t=0.308	0.759
BMI（kg/m²， $x ¯$ ±s）	25.38±3.48	24.59±3.68	t=1.24	0.217
侧别[例（%）]			χ²=1.899	0.168
左侧	54（49.09）	27（61.36）
右侧	56（50.91）	17（38.64）
病程少于1周[例（%）]			χ²=0.261	0.61
是	50（45.45）	22（50.00）
否	60（54.55）	22（50.00）
ESWL治疗史[例（%）]			χ²=0.647	0.421
有	21（19.09）	6（13.64）
无	89（80.91）	38（86.36）
主要结石位置[例（%）]			χ²=1.005	0.316
输尿管近端	72（65.45）	25（56.82）
髂血管分叉	38（34.55）	19（43.18）
主要结石
前后径［mm，M（P₂₅，P₇₅）］	7.55（5.96，9.27）	6.14（4.82，8.17）	Z=-3.144	0.002
左右径［mm，M（P₂₅，P₇₅）］	6.30（4.98，8.57）	5.25（3.98，6.91）	Z=-2.386	0.017
上下径（mm， $x ¯$ ±s）	13.46±6.29	10.98±5.61	t=2.283	0.024
体积［mm³，M（P₂₅，P₇₅）］	313.29（151.54，584.86）	156.21（76.62，357.67）	Z=-3.08	0.002
结石中心CT值［HU， $x ¯$ ±s］	778.75±308.74	723.86±387.07	t=0.925	0.357
肾门处积水宽度（mm， $x ¯$ ±s）	18.07±10.32	20.21±13.92	t=-1.05	0.295
积水宽度与结石最小径之比（ $x ¯$ ±s）	3.00±1.93	4.44±4.01	t=-2.276	0.027
尿外渗[例（%）]			χ²=0.011	0.916
有周边渗出与蔓延	69（62.73）	28（63.64）
无渗出	41（37.27）	16（36.36）
治疗侧肾实质CT值［HU，M（P₂₅，P₇₅）］	32.88（30.00，38.48）	35.49（32.60，37.78）	Z=-1.334	0.182
治疗侧肾厚径（mm， $x ¯$ ±s）	61.50±11.13	56.91±8.88	t=2.44	0.016
与对侧比较的
肾实质CT值差［HU， $x ¯$ ±s］	-3.53±6.91	-1.20±5.75	t=-1.975	0.05
肾厚径差（mm， $x ¯$ ±s）	7.38±11.81	3.42±10.53	t=1.939	0.054

预测变量	β值	SE	Wald	自由度	显著性	Exp（B）	EXP（B）的95%置信区间
预测变量	β值	SE	Wald	自由度	显著性	Exp（B）	下限	上限
结石前后径	-0.305	0.100	9.381	1	0.002	0.737	0.606	0.896
积水宽度与结石最小径之比	0.192	0.089	4.646	1	0.031	1.212	1.018	1.442
与对侧比较的肾实质CT值差	0.067	0.031	4.745	1	0.029	1.069	1.007	1.135
治疗侧肾厚径	-0.060	0.023	6.842	1	0.009	0.942	0.901	0.985
常量	4.228	1.541	7.526	1	0.006	68.555

变量	B	偏差	SE	Bootstrap	95%置信区间
变量	B	偏差	SE	显著性（双尾）	下限	上限
结石前后径	-0.305	-0.019	0.096	＜0.001	-0.533	-0.144
积水宽度与结石最小径之比	0.192	0.011	0.095	0.025	0.027	0.397
与对侧比较的肾实质CT值差	0.067	0.004	0.029	0.009	0.016	0.129
治疗侧肾厚径	-0.060	-0.004	0.023	0.002	-0.111	-0.023
常量	4.228	0.310	1.605	0.003	1.499	8.069

References 27

1	倪颖, 周金才, 王启明, 等. 硬镜联合软镜与单纯软镜下钬激光治疗肾盂出口及输尿管近端结石的比较研究 [J]. 现代医学, 2020, 48(3): 345-347.
2	蒋立量, 杨嗣星. 输尿管通达鞘及其临床应用 [J]. 微创泌尿外科杂志, 2017, 6(2): 124-128.
3	中华医学会泌尿外科分会, 中国泌尿系结石联盟. 软性输尿管镜术中国专家共识 [J]. 中华泌尿外科杂志, 2016, 37(8): 561-565.
4	Cetti RJ, Biers S, Keoghane SR. The difficult ureter: what is the incidence of pre-stenting? [J/OL]. Ann R Coll Surg Engl, 2011, 93(1): 31-33.
5	倪颖, 张铁龙, 王岗, 等. 未预置支架逆行输尿管镜治疗近端输尿管结石手术中的困难与应对 [J/OL]. 中华临床医师杂志(电子版), 2024, 18(9): 795-801.
6	Ueki H, Inoue T, Fujita M. The lumbosacral angle is a significant predictor for using a semi-rigid ureteroscopic approach in middle ureteral stones [J]. Transl Androl Urol, 2022, 11(4): 451-459.
7	Francesca F, Scattoni V, Nava L, et al. Failures and complications of transurethral ureteroscopy in 297 cases: conventional rigid instruments vs. small caliber semirigid ureteroscopes [J]. Eur Urol, 1995, 28(2): 112-115.
8	Söylemez H, Yıldırım K, Utangac MM, et al. A new alternative for difficult ureter in adult patients: No need to dilate ureter via a balloon or a stent with the aid of 4.5F semirigid ureteroscope [J]. J Endourol, 2016, 30(6): 650-654.
9	Omar M, Dorrah M, Khalifa A, et al. Randomized comparison of 4.5/6 Fr versus 6/7.5 Fr ureteroscopes for laser lithotripsy of lower/middle ureteral calculi: towards optimization of efficacy and safety of semirigid ureteroscopy [J]. World J Urol, 2022, 40(12): 3075-3081.
10	Inoue T. Editorial comment to risk factors and predictive model for incidence of difficult ureter during retrograde ureteroscopic lithotripsy [J]. Int J Urol, 2022, 29(6): 546-547.
11	Lavoie CA, Levine M, Schuler TD, et al. Understanding failures in getting it up: The prevalence and predictors of failed ureteral access in ureteroscopy [J/OL]. Can Urol Assoc J, 2021, 15(3): E135-E138.
12	Fuller TW, Rycyna KJ, Ayyash OM, et al. Defining the rate of primary ureteroscopic failure in unstented patients: A multi-Institutional study [J/OL]. J Endourol, 2016, 30(9): 970-974.
13	Cho SY, Ryang SH, Lee DS. A presumptive role of lower ureteral angles in the difficulty of ureteral access sheath insertion during retrograde intrarenal surgery [J/OL]. Int Urol Nephrol, 2020, 52(9): 1657-1663.
14	Erbaş G, Oktar S, Kiliç K, et al. Unenhanced urinary CT: Value of parenchymal attenuation measurements in differentiating acute vs. chronic renal obstruction [J/OL]. Eur J Radiol, 2012, 81(5): 825-829.
15	张福康, 邱贻辉, 黄凯清, 等. 急性单侧上尿路梗阻肾脏与肾周改变的多排螺旋CT特点及其内在联系 [J/OL]. 中华腔镜泌尿外科杂志(电子版), 2019, 13(4): 238-241.
16	Dean NS, Millan B, Uy M, et al. Ureteral wall thickness is an effective predictor of ureteral stone impaction and management outcomes: A systematic review and meta-analysis [J/OL]. J Urol, 2023, 210(3): 430-437.
17	齐伟, 席俊华, 杨晓亮, 等. 输尿管壁面积对嵌顿性输尿管结石的预测价值 [J]. 中华医学杂志, 2021, 101(44): 3637-3642.
18	Çakıroğlu B, Avcı AE, Uyanık BS, et al. The role of preoperative ureteral diameter measurements in predicting difficult access during retrograde ıntrarenal surgery: a retrospective analysis of 234 patients [J/OL]. Urolithiasis, 2025, 53(1): 104.
19	Viers BR, Viers LD, Hull NC, et al. The difficult ureter: clinical and radiographic characteristics associated with upper urinary tract access at the time of ureteroscopic stone treatment [J/OL]. Urology, 2015, 86(5): 878-884.
20	胡智玉, 郝斌, 王鹏森. 首次输尿管软镜碎石术中输尿管导入鞘放置困难患者的高危特征分析研究 [J]. 中国全科医学, 2017, 20(5): 599-602.
21	李丽娟, 张文静, 张晓伟, 等. 研究输尿管平滑肌的纤维构筑及探讨输尿管结石下降困难的机理与对策 [J]. 中国临床解剖学杂志, 2024, 42(4): 429-434.
22	杨冰, 潘东亮, 晋连超, 等. 输尿管肾盂镜钬激光碎石术后尿脓毒症相关危险因素分析 [J/OL]. 中华临床医师杂志(电子版), 2022, 16(2): 107-111.
23	张海深, 王勇, 钟涛. 肾周间隙桥隔增厚的MSCT表现及临床意义 [J]. 临床放射学杂志, 2011, 30(5): 685-688.
24	姬超岳, 肖博, 胡卫国, 等. 球囊扩张技术在输尿管镜碎石术中处理困难输尿管的有效性和安全性 [J]. 中华泌尿外科杂志, 2023, 44(2): 109-114.
25	杨文刚, 赖义明, 黄浩, 等．斜跨位上下联通置入Allium覆膜输尿管支架治疗输尿管狭窄的初步经验 [J/OL]. 中华腔镜泌尿外科杂志(电子版), 2024, 18(4): 340-345.
26	Özman O, Çınar Ö, Çakır H, et al. Is it a good strategy to proceed a retrograde intrarenal surgery session sheathless after ureteral access sheath insertion failure? A RIRSearch study [J/OL]. J Endourol, 2023, 37(7): 747-752.
27	林宇腾, 延敏博, 许家榕, 等. 输尿管软镜手术术后住院时间的影响因素分析 [J/OL].中华腔镜泌尿外科杂志(电子版), 2025, 19(1): 41-46.

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