肝肾联合切取对移值肾功能恢复的影响及其对策

目的 探讨肝肾联合切取对移植肾近期肾功能的影响。方法 比较52例肝肾联合切取供肾肾移植受和118例单独肾脏切取供肾肾移植受近期肾功能的差异。结果 肝肾联合切取肾移植受术后第1天尿量平均为8491mL，术后第4天血肌酐平均为298μmol／L；肾脏单独切取受分别为10898mL和181μmol／L，两有显性差异。结论 肝肾联合切取影响供肾质量，肝肾联合切取时应注意保护供肾。     

肝肾联合移植中肝脏对肾脏的保护作用

目的探讨肝肾联合移植中肝脏对肾脏的保护作用。方法回顾性分析2001年10月至2006年6月18例接受肝肾联合移植患者的资料,并以同一供体的对侧肾脏所完成的单独肾移植18例受者作为对照,2组患者年龄、性别、血型、冷热缺血时间、人类白细胞抗原（HLA）配型、肾病原发病、免疫抑制方案等条件基本匹配。对2组患者间移植肾急性排斥反应（AR）、慢性排斥反应（CR）、移植肾功能延迟恢复（DGF）的发生率以及出院时血肌酐（SCr）水平进行比较。结果肝肾联合移植组AR和DGF发生率均明显低于单独肾移植组,差异有统计学意义（5．6％对33．3％,P= 0．044;0对27．8％,P=0．023）;肝肾移植组CR发生率明显低于单独肾移植组,但差异无统计学意义（0对11．1％,P=0．243）。出院时平均SCr水平肝肾移植组明显低于单独肾移植组,差异有统计学意义[（57．1±6．0）μmol／L对（123．0±11．7）μmol／L,P=0．018）]。结论肝肾联合移植中肝脏对肾脏具有保护作用,能够维持良好的移植肾功能。     

边缘供者供肾对肾移植受者早期预后的影响

目的 分析边缘供者供肾对亲属活体肾移植受者早期预后的影响.方法 66例亲属活体肾移植病例按供体年龄和供体情况分为边缘供者组(28例)和非边缘供者组(38例).对照比较2组的手术前后患者SCr、内生肌酐清除率、内外科并发症等情况.结果边缘供者组和非边缘供者组受者在术后第7天、1和3个月SCr分别为154、131、127μmol/L和132、117、118/μmol/L,2组之间比较差异无统计学意义(P＞0.05);2组父母子女间供肾受者的SCr在术后第7天、1、3个月分别为160、131、126 μmol/L和132、129、126μmol/L,2组之间比较差异均无统计学意义(P＞0.05)}边缘供者供肾受者内外科并发症发生率、内生肌酐清除率与非边缘供者供肾受者比较差异无统计学意义.结论 边缘供者供肾的早期临床疗效理想.严格控制其纳入标准,边缘供者尤其父母子女间的边缘供者可作为亲属活体肾移植供体.     

机器人辅助腹腔镜与后腹腔镜活体供肾切取术的临床研究

目的比较机器人辅助腹腔镜活体供肾切取术与后腹腔镜活体供肾切取术的临床疗效,评估机器人辅助腹腔镜供肾切取术对供、受者的安全性和有效性。方法回顾性分析2013年9月至2015年8月第四军医大学西京医院泌尿外科31例行机器人辅助腹腔镜活体供肾切取术(机器人组)及29例行后腹腔镜活体供肾切取术(后腹腔镜组)供、受者临床资料。比较机器人组和后腹腔镜组供者术前一般情况、手术时间、热缺血时间、术中出血量、住院时间、并发症发生情况、术后随访情况,以及两组受者手术前后血清肌酐值、手术并发症和术后移植肾功能。计量资料组间比较采用t检验,计数资料组间比较采用χ2检验。结果机器人组与后腹腔镜组手术均顺利完成。两组供者术中出血量分别为(39±15)和(62±37)m L,住院时间分别为(4.6±1.0)和(5.4±1.5)d,差异均有统计学意义(t=3.01和2.46,P均0.05);手术时间、热缺血时间及并发症发生率差异均无统计学意义(P均0.05)。此外,机器人辅助腹腔镜组2例供者术中出现脾脏损伤,1例出现术后出血;后腹腔镜组1例供者术后出现泌尿系统感染,1例术后术后第6天发现髂外静脉血栓,1例术后出现伤口脂肪液化。两组供者术后随访6个月以上,均无高血压、蛋白尿、肾功能异常等并发症发生。两组受者术后第7、30天血清肌酐值分别为(120±26)和(132±43)μmol/L,(115±18)和(118±39)μmol/L,差异均无统计学意义(t=0.78和0.96,P均0.05)。机器人组及后腹腔镜组受者移植肾存活比例分别为100.0%(31/31)和96.6%(28/29)。结论机器人辅助腹腔镜活体供肾切取术具有安全、可靠、创伤小、恢复快、不影响供移植肾功能等优势,是一种可供选择的供肾切取方式。     

腹腔镜技术获取活体供肾的基础研究

目的探讨建立小猪腹腔镜活体供肾切取和原位肾移植模型的可行性以及CO2气腹对小猪移植肾功能恢复及组织形态的影响。方法 40头滇南小耳猪经配型分为CO2气腹腹腔镜活体供肾切取组（LDN组,n=20）和开放活体供肾切取组（ODN组,n=20）,每组供、受体均为10头;两组分别采用腹腔镜和开放手术经腹膜后入路切取供肾后行原位肾移植。术后监测尿量、血清肌酐（SCr）及血尿素氮（BUN）;术后30d切取移植肾组织制作石蜡切片用于组织病理检查。结果 LDN组和ODN组均成功建立6例小猪原位肾移植模型,移植成功率均为60%（6/10）。LDN组和ODN组热缺血时间分别为（89±6）s和（30±11）s,差异有统计学意义（t=11.53,P〈0.05）。术后第3天LDN组和ODN组SCr分别为（152±16）μmol/L和（126±8）μmol/L,BUN分别为（7.26±0.99）mmol/L和（2.87±0.39）mmol/L,差异均有统计学意义（F=11.003,P〈0.05;F=6.303,P〈0.05）;术后第7天LDN组和ODN组SCr分别为（121±5）μmol/L和（89±10）μmol/L,BUN分别为（2.87±0.39）mmol/L和（1.63±0.38）mmol/L,差异均有统计学意义（F=48.301,P〈0.05;F=31.719,P〈0.05）。移植肾组织病理检查结果：HE染色显示LDN组移植肾肾小管上皮细胞损伤、肾间质水肿及炎性细胞浸润较ODN组稍重,但差异无统计学意义（P〉0.05）;过碘酸-Schiff染色及Masson染色显示两组移植肾病理改变无特异性。结论腹腔镜活体供肾切取术可影响移植肾的早期恢复,但对术后晚期移植肾功能及病理改变的影响与开放活体供肾切取术比较无差异。建立小猪经腹膜后入路腹腔镜活体供肾切取和原位肾移植模型具有可行性。     

供体年龄对活体肾移植预后的影响

目的 探讨供体年龄对活体肾移植预后的影响.方法 回顾性分析2004年至2011年间在我院实施的活体亲属肾移植217例,按供体年龄或供受体年龄差异分组,随访并比较各组受者的血肌酐水平和术后并发症情况.结果 随着供体年龄的增长,受体移植术后血肌酐水平呈上升趋势.与供受体年龄差＜-5岁组比较,供体年龄差＞5岁组的Scr水平在1个月[(143.5±42.1) μmol/L比(114.4±30.4)μ mol/L]、3个月[(139.9±36.6) μmol/L比(110.6 ±33.3)μmol/L]、1年[(132.1±22.1)μmol/L比(105.5±35.9) μmol/L]及2年(132.0±45.4) μmol/L比(97.2±17.5) μmol/L]均增高,差异有统计学意义(均P＜0.05).与年轻供肾组(＜50岁)相比,老年供肾组(＞50岁)的急性排斥反应发生率(19.4％比9.7％)和慢性排斥反应发生率(9.7％比1.4％)也显著增高(均P＜ 0.05).术后人及肾的存活率比较差异无统计学意义.供受体年龄差异是术后2年Scr水平异常的独立危险因素(OR=5.010,P＜0.05).结论 供体年龄是肾移植预后的重要影响因素,老年供肾的疗效较差.     

70岁以上老年供肾活体肾移植18例疗效分析

目的探讨70岁以上老年供肾活体肾移植的临床疗效。方法以2017年9月至2019年6月中国科技大学附属第一医院(安徽省立医院)肾移植科18例供者年龄超过70岁的活体肾移植供、受者为研究对象, 收集围手术期临床资料和随访数据, 根据单侧供肾肾小球滤过率(GFR)是否低于40 ml/(min·1.73 m2)分为低供肾GFR组(8例)和正常供肾GFR组(10例), 分别对两组血肌酐和移植肾存活率等参数进行统计学分析。同时回顾性分析术后并发症等随访结果。结果 18例供、受者均手术顺利, 未发生严重围手术期并发症和二次手术;受者术后未发生移植物功能延迟, 围手术期出现急性排斥反应1例(5.6%), 术后第3天平均血肌酐(155.7±63.5)μmol/L, 出院时血肌酐(97.6±28.7)μmol/L;随访时间37.5个月(27～48个月), 18例供者术后恢复顺利, 随访期间健康状况良好, 未发生蛋白尿、供肾手术相关住院或死亡, 出院血肌酐(86.8±18.3)μmol/L, 末次随访血肌酐(84.4±15.0)μmol/L, 两组差异无统计学意义(P=0.610);18例受者随访期间受者、...     

亲属活体肾移植供者的安全性分析

目的 分析亲属活体肾移植供者手术前后的相关指标变化,探讨活体供者的安全性.方法对132例亲属活体供肾者进行心理和生理分析,包括尿常规、血生化、肾小球滤过率(GFR)、内生肌酐清除率(CCr)和生活质量等指标.结果 132例供肾者的生活质量评分与正常人群比较差异无统计学意义(P＞0.05).供肾切取术前供者血肌酐(SCr)为(78.33±15.94)μmol/L,术后7 d为(108.49±19.88)μmol/L(P=0.000);术后6个月为(112.47±20.38)μmol/L,与术后7 d比较差异无统计学意义(P=0.109).供肾切取术前供者CCr为(95.80±20.92)ml/min,术后7 d为(57.36±14.92)ml/min,与术前比较P=0.017;术后6个月为(65.49±8.25)ml/min,与术后7 d比较差异无统计学意义(P=0.619).术前双肾GFR为(74.08±18.51)ml/min,右肾GFR为(38.43±10.33)ml/min,供肾切取术后6个月保留右肾GFR为(56.49±13.01)ml/min,与术前双肾GFR比较,P=0.000;保留右肾GFR与术前自身比较代偿性增加47.0%.手术并发症包括脾脏包膜下出血1例,降结肠破裂1例,切口脂肪液化5例. 结论 术前对供肾者进行充分系统的医学心理学和生理学评估,严格履行风险告知义务,供受者术中规范操作,围手术期合理管理和建立严密的随访制度,可以有效提高亲属活体移植供肾者的心理和生理安全性.     

马方综合征来源供肾肾移植2例并文献复习

目的 探讨马方综合征（MFS）患者供肾肾移植的可行性及临床经验。方法 回顾性分析接受同一MFS患者供肾的2例受者临床资料及既往文献中2例相关报道,总结MFS患者供肾肾移植的特点和临床诊疗要点。结果 该MFS患者左、右侧供肾零点穿刺Remuzzi评分分别为1分、2分,肾内小动脉壁与其他脑死亡及心脏死亡供肾相比无明显差异。接受该MFS患者肾脏的2例受者术后均发生移植物功能延迟恢复,短暂血液透析后,左肾受者、右肾受者的移植肾功能分别于术后10 d和20 d起开始逐渐恢复。出院后左肾受者的血清肌酐稳定于80～90μmol/L,右肾受者的血清肌酐仍在下降,截至投稿日,血清肌酐最低为232μmol/L（术后43 d）。既往文献中报道了2例成功使用同一MFS患者供肾的肾移植案例,2例受者均发生了移植物功能延迟恢复,而后肾功能均恢复正常,截至报道日期,其中1例受者持续存活了6年,另外1例受者于术后第2年因新发脑血管疾病而死亡。结论 MFS患者是可接受的供肾来源,但术前应审慎评估受者意愿和一般状况,术中妥善处理可能的肾动脉中膜撕裂,术后警惕各类并发症的发生。     

婴幼儿单供肾成人受者移植39例报道

目的总结婴幼儿单供肾成人受者肾移植的临床近期效果。方法 2014～2016年间接受3岁以下婴幼儿单供肾移植的成人受者39例,依据供者年龄分为0～1岁婴儿供肾组(9例)和1～3岁幼儿供肾组(30例),统计术后1年内肾存活情况、肾功能状况、移植肾功能延迟恢复(DGF)发生率及并发症情况。结果两组术后未见原发性无功能(PNF)和外科并发症导致的移植肾失功病例,婴儿供肾组死亡2例,死因均为间质性肺部感染;幼儿供者组死亡2例,死因分别为肺部感染与不明原因猝死,死亡删失的移植肾存活率两组均为100%。两组受者术后1年的血肌酐水平分别为(74.14±18.52)μmol/L和(91.46±26.91)μmol/L,差异无统计学意义(P0.05)。DGF发生率,婴儿供肾组44.4%(4/9),幼儿供肾组26.7%(8/30),差异无统计学意义(P0.05);两组术后蛋白尿发生率分别为33.3%和36.7%,差异无统计学意义(P0.05)。结论婴幼儿单供肾移植给低体重成人受者,移植肾近期存活效果良好,可扩展器官来源。但是术后早期蛋白尿发生率较高,可能与供肾高滤过损伤有关。     

Reassessing the Significance of Intimal Arteritis in Kidney Transplant Biopsy Specimens

Intimal arteritis (the presence of v-lesions) in kidney transplant biopsy specimens is believed to have major prognostic and diagnostic significance. We assessed the relationship of v-lesions to prognosis in 703 indication biopsy specimens and used microarray-based molecular tests to re-examine the relationship of v-lesions to rejection. v-Lesions were noted in 49 specimens (7%) and were usually mild (v1). The presence of v-lesions had no effect on graft survival compared with the absence of v-lesions. Pathologists using current conventions almost always interpreted v-lesions as reflecting T cell–mediated rejection (TCMR), either pure or mixed with antibody-mediated rejection (ABMR). The molecular scores questioned the conventional diagnoses in 29 of 49 specimens (59%), including ten that were conventional TCMR with no molecular rejection and nine that were conventional TCMR mixed with pure ABMR molecularly. The presence of tubulointerstitial inflammation (i-t) meeting TCMR criteria allowed subclassification of v-lesion specimens into 21 i-t-v-lesion specimens and 28 isolated v-lesion specimens. Molecular TCMR scores were positive in 95% of i-t-v-lesion specimens but only 21% of isolated v-lesion specimens. Molecular ABMR scores were often positive in isolated v-lesion biopsies (46%). Time of biopsy after transplantation was critical for understanding isolated v-lesions: most early isolated v-lesion specimens had no molecular rejection and were DSA negative, whereas most isolated >1 year after transplantation had positive DSA and ABMR scores. Therefore, v-lesions in indication biopsy specimens do not affect prognosis and can reflect TCMR, ABMR, or no rejection. Time after transplantation, DSA, and accompanying inflammation provide probabilistic basis for interpreting v-lesions.     

肾下盏肾盂夹角对冲击波碎石治疗肾下盏结石效果的影响

目的探讨肾下盏肾盂夹角对SWL治疗肾下盏结石效果的影响. 方法 1998年1月～2004年1月采用冲击波碎石治疗肾下盏结石263例,选择单发结石直径在0.5 cm～1.5 cm之间、肾下盏长度＜3 cm以及盏颈宽度≥5mm的42例作为研究对象, 其中肾下盏肾盂夹角≥90°者27例, 肾下盏肾盂夹角＜90°者15例. 结果 3个月后复查,42例患者总结石排净率为76%,肾下盏肾盂夹角≥90°的结石排净率为85.2%, 肾下盏肾盂夹角＜90°的结石排净率为46.7%, 两组比较有统计学差异(P＜0.05). 结论肾下盏肾盏夹角对SWL治疗肾下盏结石的疗效有影响,肾下盏肾盂夹角≥90°者明显优于肾下盏肾盂夹角＜90°者.     

End stage polycystic kidney disease: indications and timing of native nephrectomy relative to kidney transplantation

PURPOSE: We evaluated the indications for and outcome of pre-transplant, concomitant and post-transplant native nephrectomy in patients with end stage polycystic kidney disease (PCKD). MATERIALS AND METHODS: The records of 32 patients were retrospectively reviewed using the electronic database at our institution. RESULTS: Between January 1992 and December 2002, 171 patients with end stage PCKD received a kidney transplant at University of California-San Francisco. A total of 32 patients (18.7%) underwent pre-transplant (7, group 1), concomitant (16, group 2) or post-transplant (9, group 3) native nephrectomy. Of these patients 25 underwent bilateral nephrectomy. Median followup was 18 months. Indications for nephrectomy were hematuria, a renal mass and chronic pain in group 1, lack of space in group 2 and urinary tract infection in group 3. Mean operative time +/- SEM was 231 +/- 14, 370 +/- 24 and 208 +/- 14 minutes in groups 1 to 3, respectively (p = 0.001). Mean intraoperative blood loss was 533 +/- 105, 573 +/- 155 and 522 +/- 181 ml in groups 1 to 3, respectively (p not significant). Two group 2 patients required blood transfusions. Postoperative complications requiring surgical intervention included wound dehiscence in group 1 and abdominal bleeding in group 3. Mean hospital stay was comparable among groups 1 to 3 at 7 +/- 0.7, 8.6 +/- 1.2 and 6.3 +/- 0.6 days, respectively (p not significant). At 3 months mean serum creatinine was not significantly different between groups 2 and 3 at 1.3 +/- 0.1 and 1.5 +/- 0.2 mg/dl, respectively. CONCLUSIONS: Unilateral or bilateral nephrectomy for PCKD at transplantation is safe in terms of postoperative patient morbidity and graft function. We perform concomitant native nephrectomy when indicated, preferably in recipients of living donor kidney transplants.     

Clinical efficacy of a combination pneumatic and ultrasonic lithotrite

PURPOSE: A new combination pneumatic/ultrasonic intracorporeal lithotriptor has been developed for percutaneous applications. It combines the stone clearing efficiency of an ultrasonic device with the fragmentation strength of a pneumatic probe into a single handpiece. We present our early clinical experience with this device in a prospective, randomized comparison a combination pneumatic/ultrasound lithotrite and standard ultrasonic lithotripsy. MATERIALS AND METHODS: A total of 20 consecutive patients undergoing percutaneous nephrolithotomy for symptomatic calculi were randomized to receive stone fragmentation and removal using a standard ultrasonic device or a new combination pneumatic/ultrasonic unit. Stone location and burden were assessed before the operative procedure. The stone clearance rate in mm.2 per minute was calculated for the 2 devices. Complications and stone-free rates were compared in the 2 groups. RESULTS: There were no significant differences in stone location and composition in the 2 groups of patients. Average time required for complete stone clearance was considerably less for the combination device (21.1 versus 43.7 minutes, p = 0.036). The opposite was true for the average rate of stone clearance in mm.2 per minute, in that the standard ultrasonic device could clear 16.8 versus 39.5 mm.2 per minute for the combination unit (p = 0.028). Stone-free and complications rates were slightly superior for the combination device but it was likely attributable to patient factors. CONCLUSIONS: The combination pneumatic/ultrasonic lithotrite is capable of disintegrating and extracting stone material at a more rapid rate than standard ultrasonic devices. Moreover, stone-free and complication rates appear to be slightly superior with the combination unit. This new combination pneumatic/ultrasonic device appears to be efficacious and safe for removing large renal calculi.     

Outcomes and Utilization of Kidneys from Deceased Donors with Acute Kidney Injury

Utilization and long-term outcomes of kidneys from donors with elevated terminal serum creatinine (sCr) levels have not been reported. Using data from the Scientific Registry of Transplant Recipients from 1995 to 2007, recipient outcomes of kidneys from adult donors were evaluated stratified by standard criteria (SCD; n = 82 262) and expanded criteria (ECD; n = 16 978) donor type and by sCr ≤1.5, 1.6–2.0 and >2.0 mg/dL. Discard rates for SCDs were ascertained. The relative risk of graft loss was similar for recipients of SCD kidneys with sCr of 1.6–2.0 and >2.0 mg/dL, compared to ≤1.5 mg/dL. For ECD recipients, the relative risk of graft failure significantly increased with increasing sCr. Of potential SCDs, the adjusted risk of discard was higher with sCr >2.0 mg/dL (adjusted odds ratio [AOR] 7.04, 95% confidence interval [CI] 6.5–7.6) and 1.6–2.0 mg/dL (AOR 2.7; CI 2.5–2.9) relative to sCr ≤1.5 mg/dL. Among potential SCDs, elevated terminal creatinine is a strong independent risk factor for kidney discard; yet, when kidney transplantation is performed elevated donor terminal creatinine is not a risk factor for graft loss. Further research is needed to identify safe practices for the optimal utilization of SCD kidneys from donors with acute kidney injury.     

The effect of treatment strategy on stone comminution efficiency in shock wave lithotripsy

PURPOSE: The comminution of kidney stones in shock wave lithotripsy (SWL) is a dose dependent process caused primarily by the combination of 2 fundamental mechanisms, namely stress waves and cavitation. The effect of treatment strategy with emphasis on enhancing the effect of stress waves or cavitation on stone comminution in SWL was investigated. Because vascular injury in SWL is also dose dependent, optimization of the treatment strategy may produce improved stone comminution with decreased tissue injury in SWL. MATERIALS AND METHODS: Using an in vitro experiment system that mimics stone fragmentation in the renal pelvis spherical BegoStone (Bego USA, Smithfield, Rhode Island) phantoms (diameter 10 mm) were exposed to 1,500 shocks at a pulse repetition rate of 1 Hz in an unmodified HM-3 lithotripter (Dornier Medical Systems, Kennesaw, Georgia). The 3 treatment strategies used were increasing output voltage from 18 to 20 and then to 22 kV every 500 shocks with emphasis on enhancing the effect of cavitation on medium fragments (2 to 4 mm) at the final treatment stage, decreasing output voltage from 22 to 20 and then to 18 kV every 500 shocks with emphasis on enhancing the effect of stress waves on large fragments (greater than 4 mm) at the initial treatment stage and maintaining a constant output voltage at 20 kV, as typically used in SWL procedures. Following shock wave exposure the size distribution of fragments was determined by the sequential sieving method. In addition, pressure waveforms at lithotripter focus (F2) produced at different output settings were measured using a fiber optic probe hydrophone. RESULTS: The rate of stone comminution in SWL varied significantly in a dose dependent manner depending on the treatment strategies used. Specifically the comminution efficiencies produced by the 3 strategies after the initial 500 shocks were 30.7%, 59% and 41.9%, respectively. After 1,000 shocks the corresponding comminution efficiencies became similar (60.2%, 68.1% and 66.4%, respectively) with no statistically significant differences (p = 0.08). After 1,500 shocks the final comminution efficiency produced by the first strategy was 88.7%, which was better than the corresponding values of 81.2% and 83.5%, respectively, for the other 2 strategies. The difference between the final comminution efficiency of the first and second strategies was statistically significant (p = 0.005). CONCLUSIONS: Progressive increase in lithotripter output voltage can produce the best overall stone comminution in vitro.     

The natural history of observed enhancing renal masses: meta-analysis and review of the world literature

PURPOSE: Standard therapy for an enhancing renal mass is surgical. However, operative treatment may not be plausible in all clinical circumstances. Data on the natural history of untreated enhancing renal lesions is limited but could serve as a decision making resource for patients and physicians. We examined available data on the natural history of observed solid renal masses. MATERIALS AND METHODS: A Medline review of the literature was performed from 1966 to the present regarding untreated, observed, localized solid renal masses. To these data we added our institutional experience with a total of 61 lesions observed in 49 patients for a minimum of 1 year. Variables examined were initial lesion size at presentation, growth rate, duration of followup, pathological findings and progression to metastatic disease. Overall weighted mean estimates were calculated for lesion size at presentation, growth rate and followup based upon combining single institutional series with complete information. RESULTS: We identified 10 reports from 9 single institutional series in the world literature regarding the natural history of untreated solid localized renal lesions. The series included 6 to 40 patients (mean 25) with a mean followup of 30 months (range 25 to 39). When combined with our institutional data, a total of 286 lesions were analyzed, of which 234 could be included in the meta-analysis. Mean lesion size at presentation was 2.60 cm (median 2.48, range 1.73 to 4.08). Meta-analysis revealed a mean growth rate of 0.28 cm yearly (median 0.28, range 0.09 to 0.86) at a mean followup of 34 months (median 32, range 26 to 39) in all series combined. Pathological confirmation was available in 46% of the cases (131 of 286) and it confirmed 92% (120 of 131) as RCC variants. Evaluable data in this subset of confirmed RCC demonstrated a mean growth rate of 0.40 cm yearly (median 0.35, range 0.42 to 1.6). Lesion size at presentation did not predict the overall growth rate (p = 0.46). Progression to metastatic disease was identified in only 1% of lesions (3 of 286) during followup. CONCLUSIONS: The majority of small enhancing renal masses grow at a slow rate when observed. Although metastatic and cancer specific death are low, serial radiographic data alone are insufficient to predict the true natural history of these lesions. Therefore, physicians and patients assume a calculated risk when following these tumors. Basic biological data are needed to assess the natural history of untreated renal masses.