Analysis of trends on serial ultrasound for high grade neonatal hydronephrosis

Postnatal management of children with antenatal hydronephrosis

Background

Postnatal management of infants with antenatal hydronephrosis (ANH) is still one of the most controversial issues. The majority of infants with ANH are asymptomatic with only few children who develop renal insufficiency. Thus, the biggest challenge for pediatric urologists is to distinguish children who will require further investigations and possible intervention prior to the development of symptoms, complications or renal damage in a cost effective manner without exposing them to the hazards of unnecessary investigations.

Main body

In this review article, literature on ANH were reviewed to present the current suggestions, recommendations, guidelines and their rational for postnatal management of ANH. It is agreed that a large portion of infants with ANH will improve; thus, the protocol of management is based mainly on observation and follow-up by ultrasound to detect either resolution, stabilization or worsening of hydronephrosis. The first 2 years of life are critical for this follow-up as the final picture is mostly reached during that period. Advanced imaging using voiding cystourethrography or renal scintigraphy are required for children at risk. Then, surgical intervention is selected only for a subgroup of these infants who showed worsening of hydronephrosis or renal function.

Conclusions

The protocol of management is based mainly on observation and follow-up by US to detect either resolution, stabilization or worsening of hydronephrosis. Postnatal evaluation should be performed for any neonate with a history ANH at any stage during pregnancy even if it was resolved during third trimester. Exclusion of UTI should be performed by urinalysis for all cases followed by urine culture if indicated. Serum creatinine should be performed especially in patients with bilateral ANH. US is the initial standard diagnostic imaging technique. Other imaging modalities like VCUG and nuclear renal scans may be required according to the results of the US evaluation. The most important items in decision making are the presence of bilateral or unilateral hydronephrosis, presence or absence of hydroureter, presence of lower urinary tract obstruction and degree of hydronephrosis on the initial postnatal US. Then an intervention is selected only for a subgroup of these patients who showed deterioration in renal function or degree of hydronephrosis or were complicated by UTIs. All these recommendations are based on the available literature. However, management of ANH is still a controversial issue due to lack of high evidence-based recommendations. Randomised controlled studies are still needed to provide a high level evidence for different aspects of management.

Urinary Ultrasound and Other Imaging for Ureteropelvic Junction Type Hydronephrosis (UPJHN)

Ultrasound is the main imaging study used to diagnose ureteropelvic junction (UPJ) obstruction. On ultrasound, abnormal dilatation of the pelvicalyceal system of varying degrees is seen, whereas the ureter is normal in caliber. A properly performed study provides essential information regarding laterality, renal size, thickness, and architecture of the renal cortex and degree of dilatation of the pelvicalyceal system. Doppler ultrasound may identify a crossing vessel, when present. This imaging method also has been used differentiating obstructive from non-obstructive hydronephrosis by renal arterial resistive index measurements. Abdominal radiographs may show soft tissue fullness, bulging of the flank, and displacement of bowel loops from the affected side. The voiding/micturating cystourethrogram helps exclude other causes of upper tract dilatation, including vesicoureteral reflux, urethral valves, and ureteroceles. Computerized Tomography angiography with multiplanar reformation and three-dimensional images may be used to depict suspected crossing vessels as a cause of UPJ obstruction in older children and adults. Magnetic Resonance Urography has progressed significantly in recent years due to the development of both hardware and software that are used to generate high-resolution images. This imaging technique currently allows for the detailed assessment of urinary tract anatomy, while also providing information regarding renal function, including differential renal function, and the presence or absence of obstructive uropathy.

Hydronephrosis severity score: an objective assessment of hydronephrosis severity in children-a preliminary report

The main challenge in the management of antenatally diagnosed hydronephrosis and ureteropelvic junction obstruction (UPJO) is to differentiate the one that is likely to resolve from the pathological one. In this study, a new hydronephrosis severity score (HSS), combining ultrasonographic and renographic parameters, has been developed. Hydronephrosis severity score was analyzed with regard to its usefulness in assessing the severity of UPJO, postoperative resolution, and interobserver reliability.

METHODS

Hydronephrosis severity score was devised with three parameters: differential renal function (DRF), drainage curve pattern, and ultrasonogram grade (Table 1). Hydronephrosis severity score ranges were divided as 0-4, mild; 5-8, moderate; and 9-12, severe and compared with clinical outcomes (resolution, persistence, or surgical intervention) by retrospective case record review of children with unilateral UPJO. Among those who underwent surgery, surgical outcomes were compared with changes in HSS at 6-month follow-up. Hydronephrosis severity score was computed by three observers, and interobserver variability was calculated.

RESULTS

A total of 125 case records (male:female = 93:32; right:left = 44:81) were analyzed. Among the patients analyzed, none (0/59) with HSS 0-4 warranted surgery, whereas 1 of 35 patients with HSS 5-8 underwent surgery, and all (31/31) with HSS 9-12 underwent surgery (P = 0.001). Overall, hydronephrosis resolved in 65, persisted in 28, and required surgery in 32 patients. Mean (standard deviation) HSS was 2.1 (0.75) in whom it resolved, 6.2 (0.78) in whom it persisted, and 10.2 (0.79) in those who underwent surgery (analysis of variance P = 0.001). Among those who underwent surgery, a better recovery of HSS was noted in younger infants (aged 2-5 months) with higher pre-operative DRF. There was 94.4% median agreement between radiologists and the surgeon (kappa 0.851), indicating a very good interobserver agreement.

DISCUSSION

Loss of DRF on progressive renograms remains the accepted criterion of significant UPJO although the lost function does not always recover after pyeloplasty. Newer scoring systems keep evolving to predict the need for surgery as well as assess resolution of UPJO, and the study's preliminary report suggests that HSS could turn out to be one such useful tool. In this study, those who deteriorated were the ones with HSS ≥9. One can use this as a criterion and decide on intervention before DRF deterioration. Hydronephrosis severity score could also be applied as an objective parameter for quantifying improvement/deterioration after surgery and comparing outcomes across centers. The drawbacks of the present study are its small size and the retrospective nature. Further prospective studies are required to validate the usefulness of HSS.

The molecular biology of pelvi-ureteric junction obstruction

Over recent years routine ultrasound scanning has identified increasing numbers of neonates as having hydronephrosis and pelvi-ureteric junction obstruction (PUJO). This patient group presents a diagnostic and management challenge for paediatric nephrologists and urologists. In this review we consider the known molecular mechanisms underpinning PUJO and review the potential of utilising this information to develop novel therapeutics and diagnostic biomarkers to improve the care of children with this disorder.

Usefulness of Ultrasonography and Cortical Transit Time to Differentiate Nonobstructive From Obstructive Dilatation in the Management of Prenatally Detected Pelvic Ureteric Junction Like Obstruction

OBJECTIVE

To differentiate a nonobstructive dilatation from an obstructive dilatation in prenatally detected presumed pelvi-ureteric junction obstruction so that intervention can be planned before irreversible damage can occur to the renal unit.

MATERIALS AND METHODS

From January 2012 to December 2016, all patients with prenatally detected or asymptomatic incidentally detected presumed pelvi-ureteric junction obstruction were evaluated by ultrasonography and renogram. The anteroposterior diameter of the renal pelvis was measured in supine and prone position. Presence of calyceal dilatation in prone position was noted. They were categorized into obstructed, nonobstructed, and equivocal groups based on sonography findings. The differential renal function and the cortical transit time (CTT) was calculated and compared with the sonography groups.

RESULTS

Of the 98 patients, 72 were in the obstructed, 18 were in the nonobstructed, and 8 were in the equivocal category. All except 1 in the nonobstructed category had a function of >40% with CTT of <3 minutes. Seventy patients in the obstructed category had a CTT of >3 minutes, whereas 61 had function <40% on initial evaluation. Eleven patients in the obstructed category with an initial function of >40% had CTT of >3 minutes. All of them showed increasing hydronephrosis and deterioration of function during follow-up, necessitating pyeloplasty. All patients in the equivocal group had function >40% and CTT <3 minutes.

CONCLUSION

Ultrasonography along with CTT can help to differentiate nonobstructive from obstructive dilatation.

Is it Always Necessary to Treat an Asymptomatic Hydronephrosis Due to Ureteropelvic Junction Obstruction?

The postnatal treatment of asymptomatic unilateral hydronephrosis due to ureteropelvic junction obstruction remains controversial, and the timing of and indications for surgical intervention are continuously debated. There is no consensus on the best follow-up during expectant management. The various modalities and parameters have been discussed along with their pros and cons and an attempt has been made to clear up the controversies.

Determination of the Need for Surgical Intervention in Infants Diagnosed with Fetal Hydronephrosis in China

Background

Hydronephrosis is a common congenital condition. The detection of fetal hydronephrosis by ultrasound presents a treatment dilemma. This study aims to examine postnatal follow-up and treatment for hydronephrosis diagnosed prenatally.

Material/Methods

This was a retrospective study of 210 infants with hydronephrosis diagnosed at the Qilu Hospital (Shangdong, China) between January 2005 and January 2013. The patient cohort was divided into four groups based on prenatal ultrasound examinations using the Society for Fetal Urology (SFU) classification system. Data on follow-up investigations and treatment methods were extracted from the charts and analyzed.

Results

Patients with SFU grade 1, 2, and 3 hydronephrosis (n=125, n=74, and n=11, respectively) were followed for two years. In all, 2.4%, 18.9%, and 90.9% of patients with SFU grade 1, 2, and 3 hydronephrosis, respectively, underwent surgery. SFU grade 3 (HR=9.23, 95% CI: 1.43–59.74, p=0.02), APD (HR=2.81, 95% CI: 1.11–7.10, p=0.03), and parenchymal thickness (HR=0.42, 95% CI: 0.24–0.71, p=0.001) were independently associated with the occurrence of surgery. For anterioposterior diameter, using a cut-off point of 1.1, the area under the curve was 0.86, Youden index was 0.556, sensitivity was 70.4%, and specificity was 85.3%. For parenchymal thickness, using a cut-off point of 5, AUC was 0.79, Youden index was 0.478, sensitivity was 74.1%, and specificity was 73.8%.

Conclusions

Patients with SFU grade 2 hydronephrosis require long-term follow-up. Surgery and close postsurgical observation may be necessary for patients with SFU grade 3 and 4 hydronephrosis. An initial B-mode ultrasound screening at 7–10 days after birth may help make an optimal diagnosis and treatment selection.

Predictors for the need of surgery in antenatally detected hydronephrosis due to UPJ obstruction--a prospective multivariate analysis

INTRODUCTION

Disagreement exists over the ability of different diagnostic tests to define obstruction, indications and timing of surgery and which patients will benefit from surgical intervention in antenatal hydronephrosis (ANH) due to ureteropelvic junction obstruction (UPJO). We try to find a way to predict which patients of ANH due to UPJO will eventually need surgery during conservative management.

MATERIAL AND METHODS

Prospective single centre study involving 122 renal units at a referral centre in India. Patients on conservative management were followed using a standard protocol and operated for pre-defined indications defining failure of conservative management. Patients who underwent surgery were compared with the non-operated group in terms of sex, side, baseline grade of hydronephrosis, maximum anterioposterior diameter on first postnatal ultrasound and differential renal function on first renal scan.

RESULTS

A total of 109 renal units qualified for conservative management. Of those, 23.9% required operative intervention during follow-up. Median time to failure of conservative management was 37 weeks. The median follow-up of non-operated cases was 54 months. Univariate analysis revealed that society of fetal urology (SFU) grade of hydronephrosis, anteroposterior diameter (APD), cortical thickness (CT), and pre-operative differential renal function (DRF) had a significant association with surgery (P < 0.05). Multivariate analysis revealed APD and pre-operative DRF as the only independent predictors for requiring surgery, while CT and initial SFU grade of hydronephrosis were not. Receiver operating curve analysis showed that an APD of 24.3 mm could predict the need for surgery, with a sensitivity of 73.1% and a specificity of 88.0%.

CONCLUSIONS

APD and DRF are the predictive factors for surgery. We stop short of recommending surgery only on the basis of APD. Instead we recommend that efforts be made to improve the specificity of this criterion, or by using APD in perspective with the differential renal function. We can reduce the burden of investigations in those with APD <24 mm while those with APD >24 mm can be more comprehensively monitored.

Teaching of the Society for Fetal Urology grading system for pediatric hydronephrosis is improved by e-Learning using Computer Enhanced Visual Learning (CEVL): A multi-institutional trial

INTRODUCTION

It is unclear how clinicians learn to grade pediatric hydronephrosis (HN) and how effective their training has been. We sought to: 1. Assess how clinicians learn to grade HN and their confidence in their training and abilities and 2. To assess Computer Enhanced Visual Learning (CEVL) e-Learning to learn the Society for Fetal Urology (SFU) grading system for pediatric HN.

METHODS AND MATERIALS

A multi-institutional online survey was distributed to pediatric urologists, nephrologists, and radiologists. Respondents used a 6-point Likert scale (0 = not confident to 5 = very confident) to assess their confidence in knowledge of the criteria, indications, and ability to grade HN, and how they learned to grade. Participants assigned SFU grades to 15 neonatal ultrasounds (US). A CEVL module on the SFU grading system was accessed and a post-CEVL survey completed. Changes in confidence and accuracy of grading were compared before and after CEVL e-Learning.

RESULTS

The most common method of learning was "casually during training" (44.5%). Significant increases in confidence in knowledge of criteria, indications, and ability to grade, as well as the accuracy of grading were seen following CEVL e-Learning (Figure A and B).

DISCUSSION

Although the SFU grading system is considered the predominant grading system for HN, its application in clinical practice has been inconsistent. While this may be due to the grading system itself, it is possible that deficient training and confidence are the root causes. Our data supports this by demonstrating that most clinicians receive only casual training and accordingly, report low confidence in their knowledge and ability to grade HN. Therefore, we conclude that there exists a strong need to improve the teaching of the SFU grading system. e-Learning has been shown to be effective in teaching difficult topics and skills. We demonstrate that e-Learning with CEVL is effective in increasing both the confidence and accuracy of SFU grading of pediatric HN. Limitations of our study include a small sample size, low response rate, and discrepant participation. Furthermore, we did not assess the extent to which the CEVL module was used or include a control group learning through traditional means. Therefore, we were unable to evaluate the efficiency of learning or be certain that the improvements seen were derived exclusively from CEVL.

CONCLUSION

Current training in SFU grading of HN is mostly unstructured and inaccurate grading is common. Learners who use CEVL show improvements in their confidence and ability to SFU grade HN.

Postnatal management of antenatally detected hydronephrosis

With the increasing use of ultrasonography, congenital anomalies are often picked in utero. Antenatally detected hydronephrosis is amongst the most commonly detected abnormality. The management of this condition has raised considerable debate amongst clinicians dealing with it. This article is written with an idea to provide comprehensive information regarding the postnatal management of antenatally detected hydronephrosis. A detailed review of the current literature on this topic is provided. Also, guidelines have been given to facilitate the management of this condition.

Magnetic resonance urography for diagnosis of pediatric ureteral stricture

PURPOSE

Ureteral 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 METHODS

Children 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.

RESULTS

Twenty-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.

CONCLUSIONS

MRU provides excellent anatomic and functional detail of the collecting system, leading to accurate diagnosis and management of ureteral stricture in children.

Renal parenchymal thickness in children with solitary functioning kidney

BACKGROUND

Reduced renal parenchymal thickness (PT) is a parameter used by clinicians to assess the degree of hydronephrosis. In patients with a congenital hydronephrotic solitary functioning kidney (SFK), PT is difficult to determine as there is no comparison with the contralateral kidney. The aim of this study was to obtain ultrasound measurements of PT in children with normal SFK and to compare these data with PT measurements in children with two functioning kidneys.

METHODS

This was a prospective multicenter study carried out between 2006 and 2011 in which 236 children aged 11 days to 18.96 years with healthy SFK were examined. The SFK etiologies were unilateral renal agenesis or a nonfunctioning contralateral kidney, mostly due to multicystic dysplasia. In addition to determining other parameters, we measured PT in the middle third of the kidney by ultrasound. Correlations between PT and age, height and weight were assessed.

RESULTS

Correlation analysis showed a positive correlation with renal PT for all parameters. The correlation coefficients for age, height and weight were 0.863, 0.873 and 0.874, respectively. In most age categories, the renal parenchyma was significantly thicker in the SFK than in two functioning kidneys.

CONCLUSIONS

Based on our results, we suggest that PT in the SFK is correlated with height, weight and age of the patient. Consequently, measurements of PT may be used for monitoring the development of the healthy SFK and may contribute to a more accurate assessment of the severity of SFK anomalies.

Comparison of the reliability of two hydronephrosis grading systems: the Society for Foetal Urology grading system vs. the Onen grading system

AIM

To compare the reliability of the conventional ultrasonography grading system for hydronephrosis as suggested by the Society for Fetal Urology (SFU) in 1993 and that developed by Onen in 2007.

MATERIALS AND METHODS

One hundred and eighty kidneys in 90 paediatric patients were assessed by four radiologists using each of the two grading systems twice. The SFU system was graded 0-4 (0 = no hydronephrosis; 1 = visualized only renal pelvis; 2 = plus a few caliceal dilatation; 3 = all calyceal dilatation; 4 = plus parenchymal thinning). The Onen system was graded 0-4 (0 = no hydronephrosis; 1 = only renal pelvic dilatation; 2 = plus caliceal dilatation; 3 = plus <50% renal parenchymal loss; 4 = plus >50% renal parenchymal loss). Cohen's kappa statistic was used to estimate intra- and interobserver agreement. The weighted least-squares approach was used to compare the intra-observer agreement, and bootstrapping was used to compare the interobserver agreement between the two systems.

RESULTS

Intra-observer agreement was substantial to almost perfect in both the SFU (κ 0.79-0.95) and the Onen (κ 0.66-0.97) grading system without difference. The overall interobserver agreement was substantial in both the SFU (κ 0.61-0.68) and the Onen (κ 0.66-0.76) grading system. However, interobserver agreement was fair to moderate for SFU grades 1 and 2 and Onen grades 2 and 3.

CONCLUSION

Both the SFU and Onen grading system are reliable with good intra- and interobserver agreement. However, decreased interobserver agreement was demonstrated for SFU grades 1 and 2 and Onen grades 2 and 3.

Predictive value of decreased renal pelvis anteroposterior diameter in prone position for prenatally detected hydronephrosis

PURPOSE

It is important to differentiate between those cases of prenatally detected hydronephrosis that are significant and those that are likely to resolve spontaneously. We evaluated the anteroposterior pelvic diameter of the renal pelvis postnatally in the supine and prone positions, and determined whether the difference between these 2 positions helps predict the outcome of prenatally detected hydronephrosis.

MATERIALS AND METHODS

From May 2009 to June 2011, 38 infants with prenatally detected unilateral ureteropelvic junction type hydronephrosis were evaluated. The anteroposterior pelvic diameter was noted in the supine and prone positions. Functional evaluation was done by radionuclide renogram. Those with a split function of less than 40% underwent pyeloplasty. All other patients were followed by serial ultrasound examination.

RESULTS

Six infants had an anteroposterior pelvic diameter larger than 40 mm with no change in diameter in the supine vs prone positions. Seven of 16 infants with an anteroposterior pelvic diameter between 30 and 40 mm, and 11 of 15 infants with an anteroposterior pelvic diameter between 15 and 30 mm had a smaller anteroposterior pelvic diameter in the prone position. These infants had normal renal function, improvement in hydronephrosis and did not need pyeloplasty. All the infants with no change in anteroposterior pelvic diameter in either position had poorer renal function, necessitating pyeloplasty.

CONCLUSIONS

Those cases of prenatally detected ureteropelvic junction type of hydronephrosis in which the anteroposterior pelvic diameter is smaller in the prone position than in the supine position showed improvement in hydronephrosis, while those with no change in anteroposterior pelvic diameter had worsening of hydronephrosis and needed surgical intervention.

The predictive value of the first postnatal ultrasound in children with antenatal hydronephrosis

OBJECTIVE

To evaluate the effectiveness of the first postnatal ultrasound (US) in predicting the final postnatal diagnosis using a database of children followed prospectively for antenatal hydronephrosis, and to compare these findings with a systematic review of the literature.

METHODS

The study involved 1441 children who had their radiological evaluation between 3 and 60 days of life, including an US, performed at our institution in 1998-2006. Univariate and multivariate analyses were performed. A systematic review of articles on prenatal hydronephrosis resulted in 31 studies with 2202 patients who met the inclusion criteria for analysis.

RESULTS

62.0% of renal units (RUs) had transient or non-obstructive hydronephrosis. Increasing degree of hydronephrosis correlated with increased risk of urological pathologies (from 29.6% RUs in the mild group to 96.3% RUs in the severe group). A systematic review of the literature indicated very poor quality data, but the findings appeared to be concordant with those from our patient population.

CONCLUSION

The findings from this study will help to quantify the incidence of postnatal pathology based upon the first postnatal US parameters. This information is useful for counseling and for determining which postnatal radiological tests will be necessary.

Long-term follow-up and management of prenatally detected, isolated hydronephrosis

PURPOSE

The aim of the study was to determine the outcome and management of infants with isolated hydronephrosis, detected prenatally and confirmed postnatally.

MATERIALS AND METHODS

Between January 1988 and January 2008, the files of 629 children (492 males and 137 females), who were diagnosed prenatally with isolated, unilateral hydronephrosis, and the diagnosis was confirmed postnatally, were retrospectively reviewed. The median follow-up time was 142 months. Serial ultrasonography and isotope diuretic renography nuclear imaging were performed. Hydronephrosis was assessed and classified according to the Society of Fetal Urology (SFU) grading system.

RESULTS

Initially, all of the children were treated conservatively. Stabilization occurred in all children with grade 1 hydronephrosis, in 87% of children (144) with grade 2 hydronephrosis, and in 30% of children (37) with grade 3 hydronephrosis. However, 13% of children (21) with grade 2 hydronephrosis, 70% of children (85) with grade 3 hydronephrosis, and 100% of children with grade 4 hydronephrosis received surgical intervention according to our predetermined criteria. Ninety-five patients (late pyeloplasty group) were treated for a reduction for a differential renal function (DRF) to less than 40%, and 80 children (early pyeloplasty group) underwent surgery for a DRF more than 40%, but hydronephrosis progressed to higher grades or failed to improve and had poor radiotracer clearance. Significant improvements after pyeloplasty were noted in both groups with respect to the DRF and the ratio of the depth of the calyces to the thickness of the parenchyma (C/P ratio; P < .0001). The improvement in DRF was greater in the late pyeloplasty group than the early pyeloplasty group (P = .044), whereas the improvement in the C/P ratio was greater in the early pyeloplasty group than the late pyeloplasty group (P = .001). The ipsilateral DRF was preserved in the early pyeloplasty group, whereas the ipsilateral DRF was still less than 40% in the late pyeloplasty group. The improvement in DRF was significant during the first year postoperatively and became stable thereafter. The C/P ratio was inversely correlated with the DRF in the patients before and after pyeloplasty (r = -0.257; P = .01; and r = -0.616; P = .001, respectively).

CONCLUSIONS

All infants with SFU-1 and most infants with SFU-2 hydronephrosis have relatively benign conditions and do not need an invasive procedure. Although greater improvement occurred in patients with an initial DRF less than 40%, the reduced DRF did not recover to the predeterioration level postoperatively. Earlier surgical intervention after a short period of strict clinical surveillance is beneficial for preserving renal function for patients with persistent SFU-3 or SFU-4 hydronephrosis.

The Society for Fetal Urology consensus statement on the evaluation and management of antenatal hydronephrosis

The evaluation and management of fetuses/children with antenatal hydronephrosis (ANH) poses a significant dilemma for the practitioner. Which patients require evaluation, intervention or observation? Though the literature is quite extensive, it is plagued with bias and conflicting data, creating much confusion as to the optimal care of patients with ANH. In this article, we summarized the literature and proposed recommendations for the evaluation and management of ANH.

Screening ultrasound in follow-up after pediatric pyeloplasty

OBJECTIVES

To investigate whether an initial ultrasound (US) adequately identifies those patients who need further investigation and possibly intervention while decreasing instrumentation and radiation exposure. The recommended imaging after pediatric pyeloplasty has included intravenous pyelography, radionucleotide renography, and ultrasound US.

METHODS

We retrospectively reviewed pediatric open pyeloplasty cases performed between 1999 and 2007. Of 116 patients reviewed, 49 met the inclusion criteria of unilateral pyeloplasty with pre- and postoperative US and mercaptoacetyltriglycine (MAG-3). Hydronephrosis was judged by anterior posterior pelvic diameter and caliectasis. Change in renal function on MAG-3 was defined as increase or decrease in function >5%.

RESULTS

Of 49 patients, 42 (85.7%) showed improved or stable hydronephrosis postoperatively and 7 (14.3%) showed increased hydronephrosis. Forty-six (93.8%) patients had either improved or stable renal function. Of 42 patients with stable or improved hydronephrosis, 41 (97.6%) also had stable or improved function. Comparatively, of 7 patients with increasing hydronephrosis, 2 (28.6%) showed deteriorated renal function, P = .05.

CONCLUSIONS

Postpediatric pyeloplasty imaging should aim to identify those who require further intervention. Our data demonstrate that at-risk patients can be identified with a sentinel US and selectively determine who needs further MAG-3 investigation. This should increase compliance while decreasing costs, instrumentation, and radiation exposure.

Captopril renography as a prognostic factor in obstructive hydronephrosis with preserved renal function

Hydronephrotic kidney with a differential renal function greater than 55% is defined as supranormal. The signification of this finding remains controversial. In this article, the authors reported a case of supranormal function in obstructive hydronephrosis. Differential renal functions were evaluated after administration of captopril and after pyeloplasty. The role of captopril renography as a prognostic factor for surgery is discussed.

[Postnatal follow-up of children having antenatal hydronephrosis]

The application of antenatal ultrasound for the evaluation of congenital anomalies in early pregnancy has become a common practice. Hydronephrosis is the most common anomaly observed. Antenatal interventions are experimental and done in advanced centers. Though there are defined criteria of intervention, it is still not clear as to who will benefit. Most patients will have relatively benign course, however identification of those who will have potentially serious postnatal problems permits early intervention. This study gives recommendations for the postnatal examination and follow-up of the newborns having hydronephrosis diagnosed on antenatal ultrasound.

Cold knife valvulotomy for posterior urethral valves using novel optical urethrotome

OBJECTIVES

To present our results after valve ablation using a novel cold knife urethrotome.

METHODS

Eleven consecutive male patients with posterior urethral valves underwent cold knife valvulotomy using a modified optical pediatric urethrotome. Patients were assessed both pre- and postoperatively using serum creatinine, voiding cystourethrography, and renal/bladder ultrasonography.

RESULTS

From August 2003 to August 2005, 11 patients underwent cold knife valvulotomy, of whom 7 returned for postoperative follow-up (mean follow-up 17.4 months). At surgery, the patients ranged in age from 5 days to 9 years. At presentation, 5 of the 7 patients had an elevated serum creatinine (mean 2.5 mg/dL, range 0.3-6.5), all had bilateral hydronephrosis of at least grade 3, and 6 of 7 had at least grade 3 reflux on 1 side. Intraoperatively, 1 complication (minor urethral laceration) occurred. Postoperatively, all 6 patients with serum creatinine levels measured showed improvement in renal function (mean creatinine 0.47 mg/dL, range 0.2-0.9). For the 6 patients who underwent postoperative ultrasonography, 4 had either complete resolution or significant improvement in their hydronephrosis, and none showed worsening. Six patients underwent postoperative voiding cystourethrography, with 5 showing either marked improvement or complete resolution of their reflux and 1 showing stable, unilateral reflux.

CONCLUSIONS

Valvulotomy using our modified urethrotome is a safe and effective technique for valve ablation.

Results of a practical protocol for management of prenatally detected hydronephrosis due to ureteropelvic junction obstruction

INTRODUCTION

Several algorithms exist for the management of prenatally diagnosed hydronephrosis due to ureteropelvic junction obstruction (UPJO). We utilize a conservative and practical approach emphasizing observation, with less frequent use of renal flow scans (RFS). We reviewed the results of 143 pediatric patients with congenital UPJO managed at our institution, focusing on surveillance and selective utilization of RFS, according to a standardized protocol.

MATERIALS AND METHODS

Charts of all infants with prenatally detected UPJO treated surgically or followed conservatively according to our protocol were reviewed. Patients were initially evaluated with ultrasound (US), voiding cystourethrogram, and RFS. Successive follow-up was with interval US. RFS was reserved for those with worsening hydronephrosis or that which failed to improve on US by 1 year. Radiographic studies and operative reports were examined. Gender, side of UPJO, degree of hydronephrosis, mode of management, and current status of the patients were noted.

RESULTS

The records of 143 patients and a total of 198 renal units (RU) were reviewed. The male:female ratio was 2.7. UPJO was unilateral in 88 (61%) patients and occurred more frequently on the left side (68%). Obstruction was bilateral in 55 (39%) patients. Initial US grade of hydronephrosis was Grade 1 in 56 RU (28%), Grade 2 in 51 RU (26%), Grade 3 in 50 RU (25%) and Grade 4 in 41 RU (21%). 178 RU (90%) were followed conservatively, while open dismembered pyeloplasty was the initial therapeutic approach in 20 RU (10%). The mean age at the time of surgery was 15.95+/-14.60 weeks (range 2-60). Indications included low differential renal function (DRF) (n=12), absence of tracer clearance from the renal pelvis (n=2), parental preference (n=3), and acute renal failure (n=3). Postoperative course was uneventful during 33.43+/-33.53 months (range 2-120) with favorable US and RFS results. In conservatively managed patients, mean follow-up time was 14.94+/-14.35 months (range 1.5-142). Spontaneous resolution of hydronephrosis was observed in 87 RU (49%), while 10 RU (5.6%) eventually required surgery for worsening appearance or function on US or RFS, respectively (n=8), symptom development (n=3), and/or parental preference due to persistently prolonged T1/2 (n=4). Seventy-two RU (40.4%) remain under surveillance with improvement (47.2%) or stable hydronephrosis (47.2%) in 94.4%. Decreased DRF occurred in 1 RU. Nine RU (5%) were lost to follow-up. With application of this algorithm, only 12% of patients underwent two or more RFS.

CONCLUSION

Pyeloplasty may be performed safely in infants when indicated; however, the majority of children with UPJO can be managed conservatively. Spontaneous resolution of hydronephrosis and/or favorable prognosis was encountered in 87% of conservatively managed RU. The use of a standard US grading system, selective utilization of follow-up renal function testing, and parental compliance are important factors in successful management.

Renal scintigraphy in infants with antenatally diagnosed renal pelvis dilatation

BACKGROUND/AIM

Ureteropelvic junction obstruction and vesicoureteral reflux are the most frequent entities identified on the basis of antenatal hydronephrosis. The aim of this study was to determine the incidence and pattern of abnormal renal scintigraphy findings in postnatal investigation of children with antenatal hydronephrosis.

METHODS

Twenty-four infants (19 boys and five girls) presented with antenatal hydronephrosis and mild to moderate hydronephrosis on ultrasound in newborn period were referred for renal scintigraphy. Ten patients with vesicoureteral reflux documented on micturating cystoureterography underwent 99mTc-DMSA renal scintigraphy and 14 patients were subjected to 99mTc-DTPA scintigraphy.

RESULTS

Anteroposterior pelvic diameter on ultrasound ranged from 11 to 24 mm. Renal DMSA scans identified congenital scars in two boys with bilateral reflux of grade V and unilateral reflux of grade III. Relative kidney uptake (RKU) less than 40% was found in three, and poor kidney function (RKU less than 10%) in two patients. Significant obstruction was shown on DTPA diuretic renal scintigraphy in 6/14 patients. Some slowing in dranaige (T1/2 greater than 10 minutes) with no reduction in differential renal function was identified in three patients. Differential renal function less than 10% was obtained in one case.

CONCLUSION

A high percent of abnormal renal scintigraphy findings was obtained. Renal scintigraphy was useful in determination of underlying cause of antenatally detected hydronephrosis.

Chronic partial ureteral obstruction and the developing kidney

Although congenital urinary tract obstruction is a common disorder, its pathophysiology remains poorly understood and clinical practice is controversial. Animal models have been used to elucidate the mechanisms responsible for obstructive nephropathy, and the models reveal that renal growth and function are impaired in proportion to the severity and duration of obstruction. Ureteral obstruction in the neonatal rat or mouse leads to activation of the renin-angiotensin system, renal infiltration by macrophages, and tubular apoptosis. Nephrons are lost by glomerular sclerosis and the formation of atubular glomeruli, and progressive injury leads to tubular atrophy and interstitial fibrosis. Recovery following release of obstruction depends on the timing, severity, and duration of obstruction. Growth factors and cytokines are produced by the hydronephrotic kidney, including MCP-1 and TGF-beta1, which are excreted in urine and can serve as biomarkers of renal injury. Because MRI can be used to monitor renal morphology, blood flow, and filtration rate, its use might supplant current imaging modalities (ultrasonography and diuretic renography), which have significant drawbacks. Combined use of MRI and new urinary biomarkers should improve our understanding of human congenital obstructive nephropathy and should lead to new approaches to evaluation and management of this challenging group of patients.

Treatment and outcome of prenatally detected newborn hydronephrosis

OBJECTIVE

For neonates with antenatally diagnosed primary ureteropelvic junction (UPJ)-type hydronephrosis, to attempt to clarify and refine criteria for establishing optimal follow-up and treatment guidelines.

PATIENTS AND METHODS

A total of 162 newborns (228 hydronephrotic kidneys) with this condition were prospectively followed and treated by the same surgeon in 2001-2005 for a mean of 53 (13-72) months. Ultrasonography and diuretic renogram were used for diagnosis and follow up, and Onen's grading system to determine degree of hydronephrosis.

RESULTS

On first postnatal ultrasound, the severity of hydronephrosis was grade 1 in 152 kidneys (surgery, 0%), 2 in 41 (surgery, 19.5%), 3 in 19 (surgery, 42.1%), and 4 in 16 kidneys (surgery, 93.8%). All the grade 1 cases resolved spontaneously without renal deterioration (renal function >40%). Renal function ranged between 7% and 34% in grade 4 patients. Overall, 201 hydronephrotic kidneys (88.2%) resolved spontaneously, while 27 (11.8%) required pyeloplasty because of evidence of obstructive injury, including increased hydronephrosis in 14/27 (6/27 had less than 10% decrease in renal function), greater than 10% decrease of renal function in 9/27, and greater than 10% decrease of renal function as well as increased hydronephrosis in 4/27 patients (15%).

CONCLUSION

In most cases, neonatal hydronephrosis is a relatively benign condition that can be followed safely by an initial non-operative approach unless there is evidence of obstructive injury. A follow-up protocol that permits early identification of a limited number of kidneys that may develop signs of obstruction and require pyeloplasty is crucial for a favorable outcome in patients with primary UPJ-type hydronephrosis. Onen's hydronephrosis grading system promises an easier and more appropriate follow up and timely treatment for children with this condition. A sufficient follow-up interval, especially during the first 3 years of life, is essential to help prevent permanent loss of renal function in kidneys that do develop signs of obstruction.

The bear paw: a radiologic sign for congenital ureteropelvic junction obstruction

This article defines a new radiographic descriptor of high-grade hydronephrosis suggestive of ureteropelvic junction obstruction that is easily recognized by urologists and non-urologists alike. This is useful information for medical personnel participating in the management of children with hydronephrosis.

Newborn society of fetal urology grade 3 hydronephrosis is equivalent to preserved percentage differential function

PURPOSE

In newborn hydronephrosis (HN), the level of differential function (%df) measured by diuretic renography (DR) is used to judge the need for pyeloplasty. As DR testing is complex, we sought to determine if grading the level of HN (Society of Fetal Urology grade, SFU Gr) by a simple ultrasound correlates with percentage differential function (%df) and thereby obviates the need to perform DR.

MATERIALS AND METHODS

Between 1990 and 2003 our institution prospectively enrolled all cases of fetal HN who showed unilateral newborn SFU Gr HN > or =3. The cases underwent standardized testing. DR was done using the method of Well-Tempered Renography which was then followed by ultrasound (US). The US studies were performed while the hydration induced by DR was in effect. The level of %df was categorized as preserved (> or =40%) or reduced (<40%). Cases were excluded if there was an additional urological abnormality (e.g. ureterocele).

RESULTS

There were 71 cases that met our study criteria. The SFU Gr HN was 3 (n=33) or 4 (n=38). Kidneys with SFU Gr 3 HN showed preserved %df (33/33,100%) (mean=50.1+/-3.6) significantly more often than kidneys with SFU Gr 4 HN (27/38, 71%) (mean=42.2+/-13.9) (RR=1.41, 95% CI (1.15-1.72), p<0.001).

CONCLUSION

In newborns with a history of fetal HN, the postnatal finding of SFU Gr 3 HN uniformly correlates with preserved %df. Standardized hydration prior to US study is done to assure consistency in measurement of the SFU Gr HN. Determining the duration of the relationship between SFU Gr 3 HN and preserved %df will require prospective, longitudinal studies.

[Prenatal detection of primary non-refluxing megaureter. Review of our casuistics]

BACKGROUND

Most primary non-refluxing megaureters resolve spontaneously and the indications for surgery are not sufficiently well established.

OBJECTIVES

To analyze the clinical features, treatment and outcome of asymptomatic primary non-refluxing megaureter.

PATIENTS AND METHODS

We retrospectively studied 58 infants with primary non-refluxing megaureter. The diagnostic methods used were renal ultrasound, renal isotopic renogram, DMSA scan, and evaluation of renal function.

RESULTS

The mean age at postnatal diagnosis was 24 days. The mean follow-up was 4 years. Sixty-nine percent of the patients were male. Fifty-seven percent were left megaureters and 22% were bilateral (71 affected renal units). Eleven percent of megaureters were grade I, 48% were grade II, and 41% were grade III. Only nine patients (15%) received surgical treatment. The indications for surgical treatment were severe megaureter (3/9 patients; 33%), prolonged T1/2 (3/9 patients; 33%), reduced function (1/9 patients; 11%), prolonged T1/2 plus reduced function (1/9 patients; 11%) and increased dilation (1/9 patients; 11%). The mean age at surgery was 7 months. Outcomes in the non-surgical group (85% of the patients; 60 renal units) were as follows: 90% of megaureters were corrected or improved on ultrasound scan and 10% showed no change. In the first renogram, function was low in 4/60 kidneys (7%) and T1/2 was prolonged in 3/60 (5%). Finally, all kidneys in the non-surgical group had normal function, except one, which was injured from the beginning. T1/2 was normal in all kidneys. Outcomes in the surgical group (10 megaureters) were as follows: 80% of megaureters were corrected or improved after surgical intervention and 20% showed no change. At diagnosis, 4/10 kidneys (40%) had reduced function. In the post-surgical renogram 2/10 kidneys (20%) continued to show reduced function, 1/10 kidney (10%) showed restored renal function, and 1/10 kidney (10%) was nephrectomized. Initial T1/2 was prolonged in 4/10 patients (40%), and after surgery T1/2 was normal in all patients. The final DMSA scan showed 5/71 kidneys (7%) with irreversible damage (one slightly injured, two moderately injured, and three severely injured). The remaining 66 kidneys were normal. Overall renal function and blood pressure were normal in all patients.

CONCLUSIONS

Primary non-refluxing megaureter is usually a functional and benign congenital malformation that resolves during the first months of life. Although the malformation can persist, only a few patients require surgical treatment. Most authors agree that initial treatment should not be surgical and that surgery should be reserved for patients who develop ureteral dilation, a decrease in differential renal function, and/or severe symptoms during follow-up. In a few patients (7% of our series), the renal unit belonging to the megaureter shows irreversible congenital injury. In these patients, surgery is not useful.

[Prenatal diagnosis of hydronephrosis: utility of diuretic renography]

OBJECTIVE

To investigate the value of diuretic renography in patients with prenatally diagnosed unilateral hydronephrosis.

MATERIAL AND METHOD

We reviewed 44 patients who underwent ultrasonography in the first week of life and 1 month after birth, and cystography and diuretic renography at 1 month to evaluate differential renal function and the diuretic washout pattern. Patients with vesicoureteral reflux were followed-up according to the protocol for this disorder. In the remaining patients, ultrasonography and/or diuretic renography was performed every 3-6 months.

RESULTS

In 4/44 patients vesicoureteral reflux was detected as cause a of hydronephrosis. In the remaining 40 patients, diuretic renography showed a washout pattern not suggestive of obstruction in 32 (only one patient needed surgery due to pyohydronephrosis). An indeterminate washout pattern was detected in one patient (who required surgery due to worsening of the washout pattern). A pattern suggestive of obstruction was detected in seven patients, four of whom required surgery (three due to a decrease in differential renal function and one due to worsening of the degree of pelvic dilatation).

CONCLUSIONS

Diuretic renography is highly useful in risk stratification and in the management of newborn infants with hydronephrosis since infants with washout patterns not suggestive of obstruction will rarely develop obstructive hydronephrosis and can initially be followed-up with ultrasonography alone. In indeterminate and obstructive patterns, however, close monitoring that includes diuretic renography is mandatory.

Pattern of renal function deterioration as a predictive factor of unilateral ureteropelvic junction obstruction treatment

OBJECTIVES

To assess the process of renal function deterioration in patients with unilateral ureteropelvic junction (UPJ) obstruction and its impact on their treatment course.

MATERIAL AND METHODS

The files of patients treated for unilateral UPJ obstruction at our department from 1996 to 2003 were retrospectively reviewed. All patients were initially treated conservatively and followed up regularly. Criteria for conversion to surgical treatment were increase in anteroposterial renal pelvis diameter, increase in T(1/2) washout pattern, and drop of relative renal function (RRF) below 40% in diuretic renogram. Patients operated on because of multiple urinary infections, pelvic stones, or solitary kidneys were excluded. Patients were divided into group A, which included those whose treatment was converted from conservative to surgical, and group B in which patients were treated conservatively. All patients operated on underwent dismembered pyeloplasty.

RESULTS

Sixty-four patients with grade three or four hydronephrosis in postnatal ultrasound examination and an obstructive pattern in diuretic renogram were studied. All group A patients (n=47) reached an RRF below 40%; in 41 (87.2%) deterioration of RRF was detected in at least two sequential follow-up studies. In group B patients (n=17), deterioration was also detected in seven (41.1%) patients in two sequential studies (p<0.0005), although the RRF never dropped below 40%. No differences in gender, side of obstruction, or frequency of follow-up were detected between the two groups.

CONCLUSIONS

RRF deterioration and its progression for at least two sequential follow-ups could serve as a predictive factor for surgical treatment.

Conservative Treatment of Ureteropelvic Junction Obstruction in Children with Antenatal Diagnosis of Hydronephrosis: Lessons Learned after 16 Years of Follow-Up

OBJECTIVES

We attempted to define predictive factors for surgery in children with antenatal diagnosis of hydronephrosis that led to postnatal diagnosis of ureteropelvic junction (UPJ) obstruction.

METHODS

We retrospectively evaluated our 16-yr experience (1988-2003) with 343 children (260 male and 83 female) with antenatal diagnosis of hydronephrosis that led to postnatal diagnosis of UPJ obstruction and who were followed conservatively. Right-sided hydronephrosis was present in 110 and left-sided in 233 children. According to the Society for Fetal Urology (SFU) classification none had grade 0 of postnatal hydronephrosis, 20 had grade 1, 118 grade 2, 147 grade 3, and the remaining 58 children grade 4 postnatal hydronephrosis. Relative renal function (RRF) on radionuclide scans revealed 235 children with RRF>40%, 68 with RRF between 30% and 40%, and 40 patients with RRF<30%. Renal function deterioration >5% was the main indication for surgery. Commercially available software GraphPad Prism 4.0 (GraphPad prism, Prism 4 for Windows, version 4) using the Fisher exact test was used for statistical evaluation.

RESULTS

Surgical correction was needed in 179 children (52.2%) during the course of conservative management. The average age at surgery was 10.6 mo (range, 1 mo to 7 yr). Of those, 50% underwent surgery during the first 2 yr of life and the majority of the remaining patients underwent surgery between the 2 and 4 yr of age; only two patients required surgery later on. Univariate analysis revealed that child sex, side of hydronephrosis, and SFU grade of prenatal hydronephrosis were not significant predictive factors for surgery. However, SFU grade 3-4 of postnatal hydronephrosis (p<0.0001; odds ratio, 0.06281) and RRF<40% (p<0.0001; odds ratio, 0.1022) were significant independent risk factors for surgery.

CONCLUSION

In contrast with previous publications by others and by us these data show that >50% of children with antenatal diagnosis of UPJ obstruction in this series required surgical correction while on conservative protocol. SFU grade 3-4 of postnatal hydronephrosis and RRF<40% are significant independent predictive factors for surgery.

[Severe primary congenital unilateral hydronephrosis. A review of 98 cases]

INTRODUCTION

Currently, consensus is lacking on the indications for surgery in primary congenital unilateral hydronephrosis.

OBJECTIVES

To analyze the clinical characteristics, treatment and outcome of severe asymptomatic primary congenital unilateral hydronephrosis (grades 3 and 4).

PATIENTS AND METHODS

We performed a retrospective study of 98 neonates with severe primary congenital unilateral hydronephrosis. Diagnostic techniques consisted of ultrasound, renogram, and DMSA scan.

RESULTS

The mean age at diagnosis was 24 days. The mean length of follow-up was 4 years. Forty-eight percent of cases were grade 3 and the remaining cases were grade 4. Fifty-six percent of the patients received conservative treatment. Forty-four percent underwent surgery. Surgical indications consisted of prolonged T1/2, reduced differential renal function and/or very severe hydronephrosis. The mean age at surgery was 5.5 months. In 94 % of the patients who received conservative treatment, hydronephrosis resolved spontaneously. In this group, renal parenchyma and renal function were normal in all patients except two. In 97 % of the patients who received surgical treatment, hydronephrosis was corrected or improved after pyeloplasty. At diagnosis, 19 kidneys had reduced function. In the postsurgical renogram, although T1/2 had markedly improved, 8 kidneys showed reduced function. DMSA performed in 63 patients belonging to both groups, outside the active phase of hydronephrosis, revealed 8 atrophic kidneys, 4 with moderately reduced renal size and function and 4 with scarring and normal renal size and function. During the study period, overall function was maintained in all patients and none developed hypertension.

CONCLUSIONS

Severe congenital unilateral hydronephrosis resolves spontaneously in most patients. Consequently, clinicians increasingly adopt a conservative approach. The available diagnostic techniques cannot identify patients who will benefit from pyeloplasty. In general, accepted surgical indications are an increase in hydronephrosis and/or worsening of renal function. In our series, 15 % of the patients with hydronephrosis had an irreversible lesion of variable severity, which in some patients seemed to have developed during embryogenesis. Kidneys at risk of presenting a lesion were those that had grade 4 hydronephrosis.

Outcome of isolated antenatal hydronephrosis: a systematic review and meta-analysis

Idiopathic antenatal hydronephrosis (IAHN), defined as antenatal hydronephrosis not associated with other morphologic renal tract abnormalities, is the most common abnormality detected by antenatal ultrasound. We performed a systematic review and meta-analysis to determine the outcome of IAHN. We screened three databases and bibliographies to identify English-language original peer-reviewed papers that reported serial postnatal renal ultrasonography in children with IAHN. Patients who stabilized and/or improved were extracted and pooled according to the individual grading systems used by each study. A systematic analysis of data extracted from 25 articles revealed overall resolution of pelviectasis in milder cases of IAHN (Society of Fetal Urology [SFU] grade 1-2; anterior posterior pelvic diameter [APPD]<12 mm). In contrast, IAHN of higher severity (grades 3-4; APPD>12 mm) resolved with a lower frequency. Meta-analysis of data extracted from seven papers showed stabilization of pelviectasis in 98% of patients with grades 1-2 (95% confidence interval [CI] 0.93-1.0; p =0.0008) and in 51% of patients with grades 3-4 (95% CI 0.34-0.68; p <0.00001). Grades 1-2 pelviectasis was five times more likely to stabilize than grades 3-4 pelviectasis (odds ratio [OR] 4.69; 95% CI 1.73-12.76; p =0.002). We conclude that in patients with IAHN and lesser degrees of pelvic dilatation, pelvic diameter decreases to the normal range or does not worsen with the vast majority of patients. Further studies are needed to define outcomes, particularly in more severe forms of IAHN.

Variable chronic partial ureteral obstruction in the neonatal rat: a new model of ureteropelvic junction obstruction

BACKGROUND

Congenital ureteropelvic junction (UPJ) obstruction is a common developmental anomaly. To elucidate the mechanisms underlying the renal consequences of congenital UPJ obstruction, we have developed a new model of variable partial unilateral ureteral obstruction (UUO) in the neonatal rat.

METHODS

Rat pups were subjected to sham-operation, complete UUO, or variable partial UUO within the first day of life. After 14 or 28 days, the relative number of glomeruli, cell proliferation, tubular apoptosis, tubular atrophy, and interstitial fibrosis were quantitated in histologic sections. Glomerular filtration rate (GFR) was determined after 28 days of partial or complete UUO.

RESULTS

Following 70% to 75% reduction in ureteral diameter, renal growth from 14 to 28 days was reduced by 60%, and the number of glomeruli decreased by 50%. Renal pelvic diameter increased in proportion to the severity of obstruction following 14 days of partial UUO, and by 28 days, was maximally dilated regardless of the luminal diameter. Renal proliferation was increased, while tubular apoptosis, tubular atrophy, and interstitial fibrosis were less severe 14 days following partial UUO than in complete UUO. GFR was reduced by 80%, and proteinuria developed following 28 days of partial UUO.

CONCLUSION

Renal function is impaired by chronic ipsilateral partial UUO, which reduces the number of nephrons, and leads to progressive renal pelvic dilatation. Tubular atrophy and interstitial fibrosis develop prior to significant renal pelvic dilatation. Correlation of clinically measurable parameters with renal morphometry or imaging studies in this model may lead to new approaches to the management of congenital UPJ obstruction.

Congenital unilateral hydronephrosis: a review of the impact of diuretic renography on clinical treatment

PURPOSE

The natural history of and optimal treatment for asymptomatic congenital hydronephrosis is unknown, mainly because most published series are nonrandomized or retrospective with nonstandardized followup regimens. In this survey we provide an overview of the different strategies used for the treatment of congenital unilateral hydronephrosis.

MATERIALS AND METHODS

A comprehensive literature review of clinical studies of asymptomatic congenital unilateral hydronephrosis is presented.

RESULTS

Different criteria for surgical intervention and different followup regimens have been used. Identification of the population at risk has been attempted but results are ambiguous. Surgery is done in approximately 25% of cases when using deteriorating differential function, symptoms and/or increasing hydronephrosis as criteria for operation. A nonstandardized renographic assessment does not compromise evaluation of the ideal followup but it may compromise the functional outcome.

CONCLUSIONS

More studies of kidneys with decreased function, severe hydronephrosis or poor drainage investigated with a standardized protocol are needed to clarify the natural history and establish optimal guidelines for treatment and followup.