目的 探讨改良无管化经皮肾镜碎石取石术（percutaneous nephrolithotomy，PCNL）治疗2～3 cm肾下盏结石后肾下盏解剖结构变化及对术后清石率的影响。 方法 选取2020年9月至2023年9月西南医科大学附属医院泌尿外科收治的300例2~3 cm肾下盏结石患者作为研究对象，经改良无管化PCNL治疗术后疗效将患者分为清除组（n=253）和残余组（n=47），对2组患者一般资料进行单因素分析，采用限制性三次样条回归法分析肾下盏解剖结构参数变化与术后结石残余的关系；采用逐步logistic回归分析进行影响因素分析，并基于此构建列线图预测模型，绘制校准曲线、受试者工作特征（receiver operating characteristic，ROC）曲线对模型的诊断效能进行评估。 结果 2组患者在肾功能不全史（P=0.017）、肾下盏长度（infundibular length，IL）（P<0.001）、结石数量（P=0.025）、结石CT值（P=0.001）、肾下盏宽度（infundibular width，IW）（P<0.001）、手术时间（P=0.002）、肾盂漏斗部夹角（infundibulopelvic angle，IPA）（P<0.001）、肾盂肾下盏高度（pelvic caliceal height，PCH）（P<0.001）、血尿酸（uric acid，UA）（P<0.001）、尿素氮（blood urea nitrogen，BUN）（P=0.014）方面差异有统计学意义（P<0.05）；logistic回归显示调整后IL、PCH、IW、IPA仍是术后结石残余的危险因素；逐步logistic回归分析结果显示结石数量、结石CT值、IL、PCH是影响患者经改良无管化PCNL治疗肾下盏结石残余的独立危险因素，IW、IPA是保护因素（均P<0.05）；利用以上影响因素进行列线图预测模型构建，得到回归方程为Logit（P）=-2.567+0.110 9×X₁+1.170×X₂-0.226×X₃+0.023×X₄-0.442×X₅+0.714×X₆，其一致性指数0.893（95%CI=0.878~0.901），ROC曲线分析显示，模型AUC为0.888（95%CI=0.869~0.897），灵敏度为0.827，特异度为0.795，区分度较好；校准曲线提示该模型准确度较高。 结论 改良无管化PCNL治疗2~3 cm肾下盏结石是一种安全有效的方法，肾下盏结石患者可通过充分考虑解剖结构方面影响因素进行合理制定治疗方案，从而进行针对性预防，提高患者术后结石清除率。

Objective To investigate the changes in the anatomical structure of the lower renal calyx after the treatment of 2-3 cm lower renal calyx stones with improved tubeless percutaneous nephrolithotripsy（PCNL） and impact on postoperative stone clearance rate. Methods A total of 300 patients with 2-3 cm lower renal calyx stones admitted to the Department of Urology，Affiliated Hospital of Southwest Medical University between September 2020 and September 2023 were selected as the study subjects. After improved tubeless PCNL treatment，the patients were divided into clearance group（n=253） and non-clearance group（n=47）. Univariate analysis was performed on the general information of two groups of patients. The restricted cubic spline regression method was used to analyze the relationships between changes in anatomical parameters of the lower renal calyx and postoperative stone residue. Stepwise logistic regression was conducted to analyze influencing factors. Based on this，a nomogram prediction model was constructed. The receiver operating characteristic curve and calibration curve were drawn to evaluate model diagnostic effectiveness. Results There were significant differences between the two groups in history of renal dysfunction（P=0.017），infundibular length（P<0.001），number of stones（P=0.025），CT value of stones（P=0.001），infundibular width（P<0.001），surgical time（P=0.002），infundibulopelvic angle（P<0.001），pelvic calyceal height（P<0.001），uric acid（P<0.001），and blood urea nitrogen（P=0.014）. Logistic regression showed that adjusted infundibular length，pelvic calyceal height，infundibular width，and infundibulopelvic angle were still risk factors for postoperative stone residue. The results of stepwise logistic regression showed that the number of stones，CT value of stones，infundibular length，and pelvic calyceal height were independent risk factors affecting lower renal calyx stone residue in patients treated with improved tubeless PCNL，while infundibular width and infundibulopelvic angle were protective factors（P<0.05）. The influencing factors mentioned above were used to construct a nomogram prediction model. The regression equation was：Logit（P）=-2.567+0.110 9×X₁+1.170×X₂-0.226×X₃+0.023×X₄-0.442×X₅+0.714×X₆，with a consistency index of 0.893（95%CI=0.878-0.901）. The receiver operating characteristic curve showed that the area under the curve was 0.888（95%CI=0.869-0.897），the sensitivity was 0.827，and the specificity was 0.795，indicating high discrimination ability. The calibration curve indicated that the model had high accuracy. Conclusion Improved tubeless PCNL is a safe and effective method for the treatment of 2-3 cm lower renal calyx stones. Patients with lower renal calyx stones should fully consider anatomical factors before formulating treatment plans，and targeted preventive measures should be taken in clinical practice to increase the stone clearance rate after PCNL surgery.