MR urography in children

MR urography represents the next step in the evolution of uroradiology in children by combining superb anatomic imaging with quantitative functional evaluation in a single examination that does not use ionizing radiation. MR imaging has inherently greater soft-tissue contrast than other imaging techniques. When used in conjunction with dynamic scanning after administration of a contrast agent, it provides non-invasive analysis of the perfusion, concentration and excretion of each kidney. The purpose of this review is to outline our experience with more than 500 MR urograms in children. We outline our technique in detail, showing how we calculate differential renal function and how we assess concentration and excretion in the different regions of the kidney. We show that the dynamic contrast-enhanced data can be processed to yield quantitative measures of individual kidney GFR. In the clinical section we show how MR urography adds unique aspects to the anatomic evaluation of the urinary tract, and by combining the anatomic information with functional information, how we assess hydronephrosis and obstructive uropathy, congenital malformations, pyelonephritis and renal scarring.     

Evaluation of UPJ obstruction before and after pyeloplasty using MR urography

This article builds on the previous article in this symposium and shows how MR urography contributes to the postoperative evaluation of children with UPJ obstruction. By analyzing the postoperative results, we derived new insights into their preoperative evaluation. With MR urography we combine simultaneous physiological and anatomic evaluation that enables us to identify changes in renal pathophysiology that occur in association with impaired drainage and obstruction. We studied 35 children before and after pyeloplasty. The pyeloplasty was considered successful in 30 and unsuccessful in 5. Both anatomic and functional criteria were used. The anatomic parameters included the degree of hydronephrosis, the appearance of the renal parenchyma, the quality of the nephrogram and the presence of crossing vessels. The functional criteria included the renal transit time, the calyceal transit time, the volumetric differential function, the Patlak differential function, the difference between the volumetric and Patlak differential function and the Patlak number per milliliter of renal tissue. No single parameter was sufficient to fully characterize UPJ obstruction, but by synthesizing all the information we were able to subdivide UPJ obstruction into compensated, decompensated and uropathic kidneys. Decompensated systems had the most significant improvement following successful pyeloplasty. Compensated systems showed little improvement in renal function, and uropathic kidneys were associated with a poor prognosis. It is clear that not all UPJ obstructions are the same, and it seems logical that treatment should be individually tailored rather than using a standard approach for all cases. Because MR urography can identify pathophysiological differences in children with UPJ obstruction that are occult to renal scintigraphy, it has an important potential role in identifying those who will benefit most from pyeloplasty and those who are probably best observed.     

MR urography evaluation of obstructive uropathy

Hydronephrosis and the evaluation of obstructive uropathy are the most common indications for MR urography in our practice. Typically our patients fall into one of two groups: infants with antenatal hydronephrosis and older children who present with abdominal pain, hematuria or urinary tract infection. Obstruction in children is usually chronic and partial. Intermittent episodes of increased pressure occur when the urine production exceeds the capacity for drainage. MR urography uses a fluid and diuretic challenge to assess the hydronephrotic kidney. High-quality anatomic images provide a morphologic assessment of the hydronephrotic system. Although it is relatively straightforward to determine if a system is not obstructed on the basis of the renal transit time (RTT), no single parameter is adequate to fully characterize obstruction. By evaluating the changes in signal intensity in the renal parenchyma following contrast administration, the hydronephrotic systems are classified as compensated or decompensated. Delayed RTT and the presence of urine-contrast levels indicate stasis. Calyceal transit time and the difference between the volumetric and the Patlak differential renal function (vDRF-pDRF) are measures of the physiologic changes within the kidney. Additionally, MR urography provides prognostic information by assessing the quality of the renal parenchyma and identifying uropathy preoperatively. MR urography combines both anatomic and functional information in a single test and is capable of providing a comprehensive evaluation of obstructive uropathy that could ultimately help select those patients most likely to benefit from surgical intervention.     

Combined static-dynamic MR urography for the simultaneous evaluation of morphology and function in urinary tract obstruction

PURPOSE: To assess the diagnostic value of combined static-dynamic MR urography (MRU) for the functional-morphological evaluation of experimentally induced urinary tract obstruction in the piglet. MATERIALS AND METHODS: In 20 piglets unilateral ureteric stenosis was created operatively. Post-surgery repeated comparative examinations were obtained with MRU, diuretic renal scintigraphy (DRS), excretory urography (EU) and ultrasound (US). MRU was performed as a combination study with a static 3D-IR-TSE sequence and a dynamic 2D-FFE sequence after Gd-DTPA with frusemide administration. RESULTS: MRU allowed complete depiction of the prestenotic urinary tract and of the stenosis in all cases. In 43 comparative studies MRU was superior to EU in 36, EU to MRU in 2. When single kidney function was calculated with both MRU and DRS, results were highly correlated (r = 0.92). When urinary excretion was compared, significant agreement was achieved with concordant findings in 86% and slightly discordant results in 12%. CONCLUSIONS: Static-dynamic MR urography permits excellent depiction of experimentally induced urinary tract obstruction in piglets and reliable assessment of individual renal function and urinary excretion. Two advantages of the method stand out--it does not require radiation and it permits functional-morphological correlation.     

Magnetic resonance urography for diagnosis of pediatric ureteral stricture

PurposeUreteral stricture is a rare cause of hydronephrosis in children and is often misdiagnosed on ultrasound (US) and diuretic renal scintigraphy (DRS), requiring intraoperative diagnosis. We evaluated ureteral strictures diagnosed by magnetic resonance urography (MRU) at our institution.Materials and methodsChildren with ureteral stricture who underwent MRU were identified. Patient demographics, prior imaging, MRU findings, and management were assessed. The efficacy of MRU in diagnosis of stricture was compared with US and DRS. Patients with ureteropelvic or ureterovesical junction obstruction were excluded.ResultsTwenty-eight ureteral strictures diagnosed by MRU between 2003 and 2013 were identified; 22% of strictures were diagnosed by DRS ± US. The mean age at MRU diagnosis was 2.4 years (range 4 weeks–15 years). Hydronephrosis was the most common presentation, accounting for 20 (71%) cases. Other etiologies included pain (3), incontinence (2), and urinary tract infection, cystic kidney, and absent kidney, present in one case each. A mean of 2.7 imaging studies was obtained prior to MRU diagnosis. Twenty-one (75%) ureteral strictures required surgical intervention, with the approach dependent upon location.ConclusionsMRU provides excellent anatomic and functional detail of the collecting system, leading to accurate diagnosis and management of ureteral stricture in children.     

利尿性肾图在小儿肾盂输尿管连接部梗阻致肾积水诊断中的作用

目的探讨以利尿性肾图替代静脉尿路造影对小儿肾盂输尿管连接部梗阻引起的肾积水进行诊断的可能性.方法对1995年8月至2001年10月间的52例同时行静脉尿路造影和利尿性肾图检查并进行了肾盂成形术的病例进行回顾性分析,男47例,女5例,年龄0.2～13岁(平均6.5岁).结果本组52例静脉尿路造影对梗阻部位判断有52例(100%)正确;利尿性肾图检查后,52例患儿梗阻部位的判断也都(100%)正确.静脉尿路造影和利尿性肾图在梗阻部位诊断上差异没有显著性意义(P＞0.05).结论在诊断小儿肾盂输尿管连接部梗阻上,以利尿性肾图来替代静脉尿路造影是可行的.     

MR urography: the future gold standard in paediatric urogenital imaging?

Background. Examination of the paediatric urogenital tract is traditionally performed using methods that utilise ionising radiation, such as intravenous urography (IVU), computerised tomography (CT), voiding cystourethrography (VCU), and scintigraphy, in addition to ultrasound (US). Objective. To determine the potential and effectiveness of MR urography (MRU) in infants and children. Materials and methods. 44 MRU examinations were prospectively performed in 39 patients (21 infants, mean age 3.5 months, and 18 children, mean age 6 years 2 months) with known or suspected pathology of the urinary tract. Non-enhanced, fast spin-echo sequences (TSE) were performed in all patients. In 70 % of the patients a contrast-enhanced, fast gradient-echo sequence (TFE) was included. The dynamic sequence was prolonged and supplemented with furosemide provocation in some patients with suspected urinary-tract obstruction. Results. Nine percent of examinations were non-diagnostic or interrupted due to movement. MRU contributed additional information in 66 %. Nine patients with suspected urinary-tract obstruction were examined with both contrast-enhanced MRU and scintigraphy. Three MRU examinations were less informative and one equal to scintigraphy when obstruction was the diagnosis. When using a technique with a prolonged dynamic sequence, including frusemide provocation, four MRU examinations were equal and one was superior to scintigraphy. Conclusions. MRU has the potential to replace traditional diagnostic methods which use ionising radiation in paediatric patients. Further studies are needed before definite conclusions can be drawn. Received: 18 June 1998 Accepted: 9 March 1999     

儿童肾积水的影像学诊断策略

儿童肾积水最常见的病因是肾盂输尿管连接部(uteropelvic junction,UPJ)狭窄,表现为肾盂肾盏扩张积水。临床上对儿童肾积水的诊断依赖于超声、静脉肾盂造影(intravenous pyelography,IVP)、MR尿路成像(MR urography,MRU)、CT尿路成像(CT urography,CTU)、核素扫描(SPECT肾动态扫描)等多种影像学检查。不同医疗机构设备和技术不尽相同,目前诊断儿童肾积水主要有超声+IVP+MRU、超声+CTU、超声+SPECT+MRU等几种影像学检查组合。本文就儿童肾积水各种影像学诊断方法的优缺点及最佳组合方式进行解读。     

MRU在小儿泌尿系梗阻的诊断意义

目的 比较泌尿系梗阻的各种影像学诊断方法，讨论磁共振尿路造影(MRU)对泌尿系梗阻的诊断意义。方法 分析23例患儿术前行MRU检查的资料，与B超、静脉尿路造影(IVU)、逆行尿路造影、CTU等影像学诊断资料进行对比。结果 23例B超检查15例显示明确，静脉尿路造影有7例不显影或显影不清，CTU检查12例，其中8例显影，4例显影不清楚。MRU检查23例，均显影清楚。结论 MRU能显示无功能性肾脏集合系统，还有无需碘造影剂的优点，在儿童泌尿系梗阻辅助检查中有着重要作用。     

Uroradiology in the fetus and newborn: diagnosis and follow-up of congenital obstruction of the urinary tract

Abnormalities of the fetal urinary tract, most commonly hydronephrosis of differing causes, can be detected by ultrasound (US). Prenatal measurements of the kidney can help to predict the postnatal outcome of hydronephrosis. About 20 % of abnormalities evident in utero are not present after birth. After delivery, various imaging procedures, particularly US and voiding cystourethrography may be necessary to evaluate prenatally diagnosed abnormalities. Pyelectasis may be due to obstruction and this may be assessed by sonography during diuresis, urography or diuretic renography. Renography can also evaluate global and split function of the kidneys. ¹²³I-hippurate and ^{99 m}Tc-MAG3 are superior to ^{99 m}Tc-DTPA, but there is no ’gold standard' technique available to assess obstruction. The majority of cases of hydronephrosis, even those which appear to be due to obstruction, can be treated conservatively without deterioration of renal function. Primary megaureter is the second most common cause of obstructive hydronephrosis in the newborn. The diagnostic procedures are similar if the dilated ureter persists unchanged and the infant is asymptomatic. Newborns with antenatally detected renal abnormalities frequently have associated vesicoureteric reflux. Received: 6 February 1996 Accepted: 26 November 1997     

Extrinsic ureteropelvic junction obstruction from a crossing renal vessel: demography and imaging

Background. The increase in the use of prenatal ultrasound has revolutionized the detection of hydronephrosis and has had an unanticipated consequence.¶Objective. To describe the new demographics of symptomatic ureteropelvic junction (UPJ) obstruction and the characteristic imaging findings, when the obstruction is extrinsic, from a crossing renal vessel.¶Materials and methods. From a uroradiology database (1994 through 1999) we identified children with surgically corrected UPJ obstruction from intrinsic and extrinsic causes.¶Results. One hundred children had symptomatic UPJ obstruction treated by surgery. In 51 (49 %), obstruction was due to a crossing vessel. One hundred and one had UPJ obstruction detected by prenatal sonography. Only 11 (11 %) were due to a vessel. Two clinical and imaging findings were strongly suggestive of obstruction from a vessel: (1) in 5 of the 100 children the symptoms (pain, nausea, and vomiting) were intermittent. Only when symptoms were present were there hydronephrosis and obstruction; (2) in 51 of the 100 children a short segment of ureter, just below the UPJ, was filled with contrast or urine (on renal sonography, intravenous urography, or retrograde/antegrade ureterography).¶Conclusions. Extrinsic UPJ obstruction caused by a vessel is an uncommon cause of obstruction when all patients are considered. However, in symptomatic older patients whose hydronephrosis was not first identified on prenatal sonography, a vessel was the cause of obstruction in one-half.     

Utility of MR urography in children suspected of having ectopic ureter

Background

Conventional imaging modalities are limited in the assessment of complex lower urinary tract anomalies including ectopic insertion of ureters. MR urography can be useful in these situations.

Objective

To share our experience with MR urography in assessing lower urinary tract anomalies and to determine its accuracy in depicting ectopic ureters.

Materials and methods

We conducted a retrospective review of all MR urography examinations done between November 2007 and March 2013 to note the presence or absence of duplex kidneys and insertion of ureters. We reviewed patient charts, surgical findings and results of other investigations including cystoscopy with retrograde ureterogram in order to establish presence or absence of ectopic ureter. This served as a reference standard against which we compared MR urography results.

Results

Of 22 MR urography examinations (3 boys, 19 girls; age range 3–16 years, mean 9.2 years) performed during the study period, 19 were performed to rule out ectopic ureters, two to assess complex anatomy and one to rule out crossing vessel in ureteropelvic junction obstruction. MR urography showed ectopic ureter in 9/19 children; one proved to be a false-positive. MR urography correctly showed normal insertion in 7/19 children. In the remaining 3/19 children distal ureter could not be seen, hence insertion was indeterminate on MR urography. One of these children had an ectopic ureter on cystoscopy and surgery. Statistical analysis showed MR urography’s sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) to be 88.8–100%, 70–90%, 75–88.8% and 90–100% for the detection of ectopic ureter.

Conclusion

MR urography is highly accurate in the assessment of ectopic ureters. In incontinent girls, MR urography should be the method of choice for depicting or ruling out ectopic ureter.     

Combined static-dynamic MR urography for the simultaneous evaluation of morphology and function in urinary tract obstruction

Objective. A new approach, combined static-dynamic MR urography is evaluated to determine its potential utility for the functional-morphological diagnosis of paediatric urinary tract obstruction. In this initial investigation we sought to evaluate the procedure by imaging the urinary tract of piglets. Materials and methods. Twenty-nine healthy piglets were studied with MR urography (MRU), ^{99 m}Tc-MAG3 diuretic renal scintigraphy (DRS), ultrasound (US) and excretory urography (EU). The functional and morphological findings were compared. For MRU we combined a respiration-triggered 3D-IR-TSE sequence and a dynamic 2D-FFE sequence after Gd-DTPA injection. Results. MRU depicted the complete urinary tract with superior image quality compared to EU. Calculation of time-intensity curves from the dynamic sequence permitted determination of single kidney function from parenchymal ROIs and urinary excretion using the whole kidney ROI. MRU and DRS showed significant agreement in the assessment of both single kidney function and urinary excretion. Disturbances of urinary drainage were generally caused by an overfilled bladder. Conclusions. Combined static-dynamic MRU is well suited for the depiction of the complete urinary tract and for the determination of individual kidney function and urinary excretion in the piglet. Received: 21 February 2000 Accepted: 14 March 2000     

Integrated imaging of neonatal renal masses

Thirty-three neonatal renal masses were evaluated during a 2-year interval. The final diagnoses in these 33 patients were hydronephrosis [14], multicystic dysplastic kidney [10], renal vein thrombosis [3], obstructed upper pole duplication [2], polycystic kidney disease [2], nephroblastomatosis [1], and mesoblastic nephroma [1]. We recommend an integrated imaging approach that utilizes sonography to clarify anatomy and renal scintigraphy or excretory urography to determine renal function.     

Application of magnetic resonance urography in diagnosis of congenital urogenital anomalies in children

Magnetic resonance urography (MRU) has become a useful adjuvant in evaluating urogenital anomalies. In present study, we evaluated the ability of MRU in diagnosis of different congenital urogenital anomalies when the results of conventional imaging modalities were inconclusive. A total of 90 children were included in this series. The children were evaluated with T2-weighted and contrast-enhanced T1-weighted MRU sequences. The results were compared with findings obtained with ultrasonography, intravenous urography, renal nuclide scan, and voiding cystourethrography. MRU was requested in these children because conventional imaging modalities were equivocal or a co-existing urogenital anomaly was suspected. Only those cases that underwent surgery were included in this study and the surgical findings were set as the reference standard in statistical evaluation. The records of 61 boys with mean (range) age of 2.3 years (2 months-12 years) and 29 girls with mean (range) age of 3.3 years (3 months-12 years) were reviewed. The final diagnosis was ureteropelvic junction obstruction (n = 25), vesicoureteral junction obstruction (n = 16), ureterocele (n = 19), ectopic kidney (n = 11), posterior urethral valve (n = 17), and polycystic kidney (n = 2). The overall sensitivity of MRU, intravenous urography, renal nuclide scan, ultrasonography, and voiding cystourethrography in diagnosis of the aforementioned anomalies were 86, 63, 50, 44, and 41%, respectively. MRU was much more sensitive than other imaging modalities in diagnosis of end-ureteral dilation (100%) and ureterocele (89%). MRU provides a reliable noninvasive technique for imaging of the congenital anomalies in the urinary tract of children with T2-weighted MRU sequences providing unenhanced static-water images of the urinary tract as well as depicting adjacent soft-tissue lesions, and T1-weighted MRU technique imitating conventional intravenous urography. Both MRU sequences can be combined for a comprehensive examination of the urinary tract.     

The sonographically thickened wall of the upper urinary tract system: correlation with other imaging methods

Background. Sonographically detected, upper urinary tract wall thickening (UUTWT) was reported to occur in urinary tract infection, urinary tract stone disease, rejection after renal transplantation and vesico-ureteral reflux (VUR). A possible association with obstruction can be hypothesized. Objective. The assessment of a potential relationship of UUTWT with VUR or obstruction in patients without one of the above-mentioned conditions. Materials and methods. We analyzed 38 patients (74 upper urinary tracts) with at least unilateral UUTWT and concomitant imaging studies such as voiding cystourethrography (VCU), intravenous urography (IVU) and diuretic renography (DR). Results. At sonography 49 urinary tracts showed UUTWT. In 33, ipsilateral VUR could be demonstrated at VCU, 11 revealed obstruction at IVU and/or DR, and 4 showed non-obstructive pelvicalyceal dilatation at IVU and DR. In one patient, all imaging studies were normal. The positive predictive value of UUTWT for the presence of VUR was 67.4 % and for obstruction it was 22.5 %. Altogether, UUTWT indicated pathology in 98 % of urinary tracts. Conclusion. After exclusion of urinary tract infection, urinary stone disease and prior renal transplantation, the most common associated findings in UUTWT are VUR and obstruction. Therefore, VCU seems to be justified in all cases of UUTWT. Nonrefluxing systems should be further evaluated with DR and/or IVU for exclusion of obstruction. Received: 10 June 1996 Accepted: 18 January 1997     

Change in management of ureteropelvic junction obstruction]

PURPOSE: The aim of this study was to evaluate the change in ureteropelvic junction management, from surgical correction to observation of the hydronephrosis. We checked wether or not it was deleterious for kidney. MATERIALS AND METHODS: We retrospectively reviewed 96 charts between 1988 and 1998. Initial ultrasonography, and voiding cystourethrogram were available for all cases. Intravenous urography and diuretic renography were studied when available. Minimal follow-up of patients was one year. Patients were divided into three groups: surgery right away, surgery after observation, and observation only. RESULTS: Later was the diagnosis, more significant were the hydronephrosis and impairment of renal function (p < 0.01). In group operated on right away (69 cases), drainage improved, hydronephrosis decreased, but renal function did not improve significantly (p = 0.37). Sixteen patients were operated on after observation without deleterious effect for kidney. Eleven patients were only observed: hydronephrosis progressively decreased. Initial radiological results were not different between the last two groups (p > 0.05), and were not predictive of their course. CONCLUSION: Initial non operative management of hydronephrosis was not dangerous for renal function. It is advisable to detect at the earliest all signs of obstruction, because surgery improves renal drainage but not renal function.     

核素利尿肾动态显像在小儿先天性肾盂积水肾造瘘术后的应用

目的探讨^99mTc-EC利尿肾动态显像（DR）对小儿先天性肾盂积水肾造瘘术后决策第二次手术方式的价值。方法用常规^99mTc-EC肾动态显像方法,15min后静脉注射速尿,共检查肾盂积水患儿33例。34只患肾行肾造瘘术,术后随访4～12个月,根据DR检查结果,28只患肾行离断性肾盂成形术,6只行肾切除术。10只患肾在肾盂成形术后5～15个月行DR检查进一步随访。结果定量评估,肾盂成形术组9只单肾盂积水患肾在肾造瘘术前后的分肾血流灌注率（BPR）变化值为好转7只,不变2只。该组BPR值在肾造瘘术前后的差异有统计学意义（P〈0.01）。肾切除术组6只患肾的BPR变化值为不变3只,恶化3只。肾造瘘术后肾盂成形术组患侧BPR及肾有效血浆流量（ERPF）明显高于肾切除术组,两组差异有统计学意义（P〈0.01）。定性评估,肾盂成形术组28只患肾肾盂积水程度变化值为明显好转3只,好转23只,无改变2只。肾切除术组6只患肾在肾造瘘术前后肾盂积水程度的变化值均为无改变。结论DR对于小儿先天性肾盂积水肾造瘘术后的评估具有独特的价值,有助于判定第二次的手术方式,并可对肾盂成形术后肾功能的恢复进行评估。     

肾积水患儿的肾功能评估与结局预判

儿童肾积水目前的诊疗方案以保守观察为主,出现明确手术指征的肾积水患儿才进行手术治疗。然而,该诊疗方案历经几十年仍存在争议,各项检查对梗阻和肾功能受损的诊断能力、手术干预的指征和时机等问题尚未达成共识。目前肾积水的主要检查手段包括超声、同位素肾图、核磁共振等。基于对患者数据的观察分析得出的临界值、比值、分级和积分系统有助于判断哪些先天性肾盂输尿管连接部梗阻(ureteropelvic junction obstruction,UPJO)情况需要手术,而哪些可以继续观察随访;目前没有哪一项指标在诊断的敏感度和特异度上占据绝对优势。机器学习等较新的数据分析方法也正在被应用于肾积水的诊断,帮助提高超声和肾动态显像的诊断价值。此外,对尿液生物标志物诊断价值的探索工作也正在开展。本文将总结儿童肾积水的诊断方法在肾功能评估和结局预测中的价值,并对其最新进展进行评述。     

Surgical or conservative treatment of congenital hydronephrosis. Ten years' experience

BACKGROUND: Controversy exists concerning the ideal management of hydronephrosis diagnosed in the perinatal period. Different opinions depend on the absence of an accurate tool and of well-defined cut-off values for each test. For these reasons we retrospectively evaluated our management protocol. METHODS: Two-hundred and seventy-two patients with single system hydronephrosis were evaluated. Patients with bilateral hydronephrosis or with other renal or ureteral abnormalities were excluded. Diagnosis and grading of hydronephrosis were done by ultrasound. Before 1995, grade II or greater hydronephrosis was also evaluated with diuretic intravenous urography, but in cases studied afterwards, a functional evaluation of the obstruction was reached with well tempered diuretic renogram. Indications for surgery were considered: recurrent urinary tract infections, grade IV hydronephrosis, obstructive drainage pattern and differential renal function less than 40%. Patients managed non-operatively received serial re-evaluation with US-scan, urine test and functional tests if necessary. RESULTS: Hydronephrosis was on the right side in 98 cases (36%), and on the left side in the other 174 (64%). There were 129 grade I hydronephrosis (47%), 46 grade II (17%), 57 grade III (21%), 40 grade IV (15%). Fifty-seven (21%) cases of hydronephrosis underwent surgery: 49 (86%) showing obstructive pattern at functional tests, 40 (70%) presenting a differential renal function less than 40%, 5 (8%) because recurrent urinary tract infections, 40 (70%) affected by grade IV hydronephrosis. No children received nephrectomy. Average postoperative follow-up was 2.8 years: pelvic dilatation improved or remained unchanged but the obstructive pattern at functional tests always disappeared after surgery. The average follow up in the observational group of 163 patients (60%) was 4.1 years. In 149 (91%) pelvic dilatation improved, but in 14 (9%) it remained unchanged. CONCLUSIONS: The ideal management of congenital hydronephrosis is still debated since the natural history of these disease is not still completely understood and there is no accurate tool to assess these renal units. We believe that grade IV hydronephrosis always need surgery as well as those ones with recurrent urinary tract infections, longer drainage time or a differential renal function less than 40%. On the other hand grade I hydronephrosis never need surgery. Mild grade hydronephrosis can be safely managed non-operatively with a meticulous follow-up and undergoing surgery only when signs of deterioration occur.