目的: 探究成人上尿路梗阻引起肾积水的病因分布，以提高其病因学诊断的准确性。方法: 连续前瞻性收集2020年5月至2021年5月北京大学第一医院上尿路修复专业门诊新诊治的767例成人肾积水患者的临床信息，排除输尿管结石、上尿路肿瘤患者，分析成人肾积水病因。患者的肾积水病因根据其症状、病史、体格检查、超声、计算机断层扫描(computed tomography, CT)、磁共振成像(magnetic resonance imaging, MRI)、逆行肾盂造影、顺行肾盂造影、放射性核素肾图、输尿管镜检查等综合判断。结果: 767例成人肾积水患者中男性359例(46.8%)、女性408例(53.2%)，中位年龄37岁(范围14~84岁)，左侧肾积水357例(46.6%)、右侧肾积水251例(32.7%)、双侧肾积水159例(20.7%)。病因分布如下：(1) 非医源性因素464例(60.5%)，包括泌尿系统畸形355例(76.5%)、感染29例(6.3%)、盆腔脂肪增多症和(或)腺性膀胱炎23例(5.0%)、输尿管子宫内膜异位症18例(3.9%)、腹膜后纤维化15例(3.2%)、肾盂旁囊肿8例(1.7%)、外伤7例(1.5%)，其他非医源性因素12例(2.6%)，部分患者合并两种或两种以上非医源性病因。355例泌尿系统畸形的患者中，肾盂输尿管连接部狭窄252例(71.0%)。(2)医源性输尿管损伤210例(27.4%)，其中泌尿外科操作损伤112例(53.3%)，恶性肿瘤放疗损伤51例(24.3%)，妇产科手术损伤34例(16.2%)，普外科手术损伤13例(6.2%)。(3)原因不明的肾积水93例(12.1%)。结论: 成人上尿路梗阻引起肾积水的病因复杂多样，泌尿系统畸形和医源性输尿管损伤是导致成人肾积水的常见原因，从事上尿路修复工作的泌尿外科医生应熟悉每一种病因，以便明确诊断并选择出最合适的治疗方案。

Objective: To investigate the etiological distribution of hydronephrosis caused by upper urinary tract obstruction in adult patients and to improve the diagnostic accuracy for this condition. Methods: The clinical information of adult patients with newly diagnosed hydronephrosis in Upper Urinary Tract Repair Outpatient Clinic of Peking University First Hospital from May 2020 to May 2021 were prospectively and continuously collected. Patients with ureteral calculi or upper urinary tract tumor were excluded. A total of 767 patients were involved. The underlying causes of upper urinary tract obstruction were identified by senior urological surgeons according to symptoms, medical history, physical examination, and a range of diagnostic imaging techniques including ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), retrograde pyelography, antegrade pyelography, radionuclide renogram and ureteroscopy. Results: Among the 767 patients, 359(46.8%) were male and 408(53.2%) were female. The median age of these patients was 37 years (range, 14-84 years). Hydronephrosis was observed at left-sided in 357 cases(46.6%), right-sided in 251 cases(32.7%), and bilateral in 159 cases(20.7%). The causes of hydronephrosis were classified as follows: (1) Non-iatrogenic factors were found in 464 cases (60.5%). These included urinary malformations in 355 cases(76.5%), infection in 29 cases(6.3%), pelvic lipomatosis and/or cystitis glandularis in 23 cases(5.0%), ureteral endometriosis in 18 cases(3.9%), retroperitoneal fibrosis in 15 cases(3.2%), trauma in 7 cases(1.5%) and other non-iatrogenic factors in 12 cases(2.6%). Some of these patients had multiple non-iatrogenic causes. Among the 355 cases with urinary system malformations, 252 cases (71.0%) had ureteropelvic junction obstruction. (2) Iatrogenic ureteral injuries accounted for 210 cases (27.4%), including 112 cases(53.3%) of urological surgical injuries, 51 cases(24.3%) of radiotherapy for malignant tumor related injuries, 34 cases(16.2%) of gynecological and obstetrical surgical injuries, and 13 cases(6.2%) of general surgical injuries. (3) The cause of hydronephrosis remained unknown in 93 cases(12.1%). Conclusion: Hydronephrosis in adults due to upper urinary tract obstruction has a diverse range of causes, with urinary malformations and iatrogenic ureteral injuries being significant contributors. Urological surgeon involved in upper urinary tract reconstruction should be familiar with these potential causes to facilitate accurate diagnosis and effective treatment.