Fetal hydronephrosis: is there hope for consensus?

A clinical predictive model of renal injury in children with isolated antenatal hydronephrosis

Background

Antenatal hydronephrosis (ANH) affects ∼1-5% of pregnancies. The aim of this study was to develop a clinical prediction model of renal injury in a large cohort of infants with isolated ANH.

Methods

This is a longitudinal cohort study of 447 infants with ANH admitted since birth between 1989 and 2015 at a tertiary care center. The primary endpoint was time until the occurrence of a composite event of renal injury, which includes proteinuria, hypertension and chronic kidney disease (CKD). A predictive model was developed using a Cox proportional hazards model and evaluated by C-statistics.

Results

Renal pelvic dilatation (RPD) was classified into two groups [Grades 1-2 (n = 255) versus Grades 3-4 (n = 192)]. The median follow-up time was 6.4 years (interquartile range 2.8-12.5). Thirteen patients (2.9%) developed proteinuria, 6 (1.3%) hypertension and 14 (3.1%) CKD Stage 2. All events occurred in patients with RPD Grades 3-4. After adjustment, three covariables remained as predictors of the composite event: creatinine {hazard ratio [HR] 1.27, [95% confidence interval (CI) 1.05-1.56]}, renal parenchyma thickness at birth [HR 0.78(95% CI 0.625-0.991)] and recurrent urinary tract infections [HR 4.52 (95% CI 1.49-13.6)]. The probability of renal injury at 15 years of age was estimated as 0, 15 and 24% for patients assigned to the low-risk, medium-risk and high-risk groups, respectively (P < 0.001).

Conclusion

Our findings indicate an uneventful clinical course for patients with Society for Fetal Urology (SFU) Grades 1-2 ANH. Conversely, for infants with SFU Grades 3-4 ANH, our prediction model enabled the identification of a subgroup of patients with increased risk of renal injury over time.

Postnatal Evaluation and Outcome of Prenatal Hydronephrosis

BACKGROUND

Prenatal hydronephrosis (PNH) is dilation in urinary collecting system and is the most frequent neonatal urinary tract abnormality with an incidence of 1% to 5% of all pregnancies. PNH is defined as anteroposterior diameter (APD) of renal pelvis ≥ 4 mm at gestational age (GA) of < 33 weeks and APD ≥ 7 mm at GA of ≥ 33 weeks to 2 months after birth. All patients need to be evaluated after birth by postnatal renal ultrasonography (US). In the vast majority of cases, watchful waiting is the only thing to do; others need medical or surgical therapy.

OBJECTIVES

There is a direct relationship between APD of renal pelvis and outcome of PNH. Therefore we were to find the best cutoff point APD of renal pelvis which leads to surgical outcome.

PATIENTS AND METHODS

In this retrospective cohort study we followed 200 patients 1 to 60 days old with diagnosis of PNH based on before or after birth ultrasonography; as a prenatal or postnatal detected, respectively. These patients were referred to the nephrology clinic in Zahedan Iran during 2011 to 2013. The first step of investigation was a postnatal renal US, by the same expert radiologist and classifying the patients into 3 groups; normal, mild/moderate and severe. The second step was to perform voiding cystourethrogram (VCUG) for mild/moderate to severe cases at 4 - 6 weeks of life. Tc-diethylene triamine-pentaacetic acid (DTPA) was the last step and for those with normal VCUG who did not show improvement in follow-up examination, US to evaluate obstruction and renal function. Finally all patients with mild/moderate to severe PNH received conservative therapy and surgery was preserved only for progressive cases, obstruction or renal function ≤35%. All patients' data and radiologic information was recorded in separate data forms, and then analyzed by SPSS (version 22).

RESULTS

200 screened PNH patients with male to female ratio 3.5:1 underwent first postnatal control US, of whom 65% had normal, 18% mild/moderate and 17% severe hydronephrosis. 167 patients had VCUG of whom 20.82% with VUR. 112 patients performed DTPA with following results: 50 patients had obstruction and 62 patients showed no obstructive finding. Finally 54% of 200 patients recovered by conservative therapy, 12.5% by surgery and remaining improved without any surgical intervention.

CONCLUSIONS

The best cutoff point of anteroposterior renal pelvis diameter that led to surgery was 15 mm, with sensitivity 88% and specificity 74%.

Is urine intercellular adhesion molecule-1 a marker of renal disorder in children with ureteropelvic junction obstruction?

AIM

We aimed to investigate whether urine intercellular adhesion molecule-1 (ICAM-1) might serve as a marker of renal disorder in children with ureteropelvic junction obstruction.

MATERIAL AND METHODS

Twenty-nine children with severe hydronephrosis (HN) were compared with 23 participants with mild HN and with 19 healthy peers.

RESULTS

Urine ICAM-1/uCre levels were significantly higher in HN children than healthy controls (P<0.01), and in severe HN when compared with mild HN (p<0.05).

CONCLUSIONS

It seemed to us that uICAM-1 is a biomarker of renal disorder, and might have the potential to predict which patients will require surgery.

Sonographic depiction of fetal ureters

AIMS

Classic literature states that the fetal ureter should not be visible unless dilated. Our main objective was to produce an effective, reproducible method for fetal ureter depiction during an anatomic survey. Our secondary objectives were to record the frequency of visible ureters among normal fetuses and among fetuses with mild pyelectasis and also to determine the diameter of the sonographically demonstrated ureter.

SUBJECTS AND METHODS

One hundred twenty consecutive fetuses undergoing a second trimester scan were enrolled in the study. Ninety-nine anatomically normal fetuses and 21 fetuses with isolated mild pyelectasis (antero-posterior renal pelvis diameter of ≥4 mm and <7 mm) were subjected to a detailed anatomical survey. One hundred twenty fetuses were analyzed bilaterally.

RESULTS

A total of 154 (64.2%) ureters were depicted. In the first group 123 (62.1%) ureters, in the second group 31 (73.8%) ureters were depicted (p = 0.06). The diameters of the ureters ranged from 0.4 to 2.7 mm. The majority (n = 80) (52%) were visualized at both proximal and distal segments.

CONCLUSIONS

Our study demonstrates that the ureter can be demonstrated in normal fetuses and in fetuses with mild pyelectasis. Ureteral depiction is likely to be composed of normal transient passage of urine associated with peristalsis and is not always a pathological finding.

Characterizing upper urinary tract dilation on ultrasound: a survey of North American pediatric radiologists' practices

BACKGROUND

Radiologists commonly evaluate children first diagnosed with urinary tract dilation on prenatal ultrasound (US).

OBJECTIVE

To establish how North American pediatric radiologists define and report findings of urinary tract dilation on US.

MATERIALS AND METHODS

A web-based survey was sent to North American members of the Society for Pediatric Radiology (SPR) from January to February 2014. Reporting practices and interpretation of three image-based cases using free text were queried. Responses to close-ended questions were analyzed with descriptive statistics, while free-text responses to the three cases were categorized and analyzed as (1) using either descriptive terminology or an established numerical grading system and (2) as providing a quantitative term for the degree of dilation.

RESULTS

Two hundred eighty-four pediatric radiologists answered the survey resulting in a response rate of 19.0%. There is a great variety in the terms used to describe urinary tract dilation with 66.2% using descriptive terminology, 35.6% using Society for Fetal Urology (SFU) grading system and 35.9% measuring anterior-posterior diameter (APD) of the renal pelvis. There is no consensus for a normal postnatal APD or the meaning of hydronephrosis. For the same images, descriptions vary widely in degree of severity ranging from normal to mild to severe. Similar variability exists among those using the SFU system. Ninety-seven percent say they believe a unified descriptive system would be helpful and 87.7% would use it if available.

CONCLUSION

Pediatric radiologists do not have a standardized method for describing urinary tract dilation but have a great desire for such a system and would follow it if available.

Prognostic value of three-dimensional ultrasound for fetal hydronephrosis

The present study evaluated the prognostic value of three-dimensional ultrasound for fetal hydronephrosis. Pregnant females with fetal hydronephrosis were enrolled and a novel three-dimensional ultrasound indicator, renal parenchymal volume/kidney volume, was introduced to predict the postnatal prognosis of fetal hydronephrosis in comparison with commonly used ultrasound indicators. All ultrasound indicators of fetal hydronephrosis could predict whether postnatal surgery was required for fetal hydronephrosis; however, the predictive performance of renal parenchymal volume/kidney volume measurements as an individual indicator was the highest. In conclusion, ultrasound is important in predicting whether postnatal surgery is required for fetal hydronephrosis, and the three-dimensional ultrasound indicator renal parenchymal volume/kidney volume has a high predictive performance. Furthermore, the majority of cases of fetal hydronephrosis spontaneously regress subsequent to birth, and the regression time is closely associated with ultrasound indicators.

Defective bone microstructure in hydronephrotic mice: a histomorphometric study in ICR/Mlac-hydro mice

Chronic renal impairment can lead to bone deterioration and abnormal bone morphology, but whether hydronephrosis is associated with bone loss remains unclear. Herein, we aimed to use computer-assisted bone histomorphometric technique to investigate microstructural bone changes in Imprinting Control Region (ICR) mice with a spontaneous mutation that was associated with bilateral nonobstructive hydronephrosis (ICR/Mlac-hydro). The results showed that 8-week-old ICR/Mlac-hydro mice manifested decreases in trabecular bone number and thickness, and an increased trabecular separation, thereby leading to a reduction in trabecular bone volume compared with the wild-type mice. Furthermore, histomorphometric parameters related to both bone resorption and formation, that is, eroded surface, osteoclast surface, and osteoblast surface, were much lower in ICR/Mlac-hydro mice than in the wild type. A decrease in moment of inertia was found in ICR/Mlac-hydro mice, indicating a decrease in bone strength. In conclusion, ICR/Mlac-hydro mice exhibited trabecular bone loss, presumably caused by marked decreases in both osteoblast and osteoclast activities, which together reflected abnormally low bone turnover. Thus, this mouse strain appeared to be a valuable model for studying the hydronephrosis-associated bone disease.

Interactions between cytokines, congenital anomalies of kidney and urinary tract and chronic kidney disease

Fetal hydronephrosis is the most common anomaly detected on antenatal ultrasound, affecting 1-5% of pregnancies. Postnatal investigation has the major aim in detecting infants with severe urinary tract obstruction and clinically significant urinary tract anomalies among the heterogeneous universe of patients. Congenital uropathies are frequent causes of pediatric chronic kidney disease (CKD). Imaging techniques clearly contribute to this purpose; however, sometimes, these exams are invasive, very expensive, and not sufficient to precisely define the best approach as well as the prognosis. Recently, biomarkers have become a focus of clinical research as potentially useful diagnostic tools in pediatric urological diseases. In this regard, recent studies suggest a role for cytokines and chemokines in the pathophysiology of CAKUT and for the progression to CKD. Some authors proposed that the evaluation of these inflammatory mediators might help the management of postnatal uropathies and the detection of patients with high risk to developed chronic kidney disease. Therefore, the aim of this paper is to revise general aspects of cytokines and the link between cytokines, CAKUT, and CKD by including experimental and clinical evidence.

Incidence and outcomes of antenatally detected congenital hydronephrosis

BACKGROUND AND OBJECTIVES

Antenatally detected urinary tract abnormalities (ADUTA) are increasingly recognized. Our aims were to determine the incidence and outcomes of antenatally diagnosed congenital hydronephrosis in a large cohort.

DESIGN AND SETTINGS

We recorded the number of total deliveries over 4 years at King Abdulaziz University Hospital (KAUH) between January 2008 and December 2011 from the number of nursery and neonatal intensive care unit (NICU) admissions.

PATIENTS AND METHODS

We reviewed the records of 18 853 deliveries between January 2008 and December 2011 at KAUH, Saudi Arabia. ADUTA were recorded, and their postnatal medical records were reviewed for demographic and radiological data.

RESULTS

ADUTA were diagnosed in 327 fetuses (1.7%). The commonest pathology was congenital hydronephrosis (n=313, 95.7%). Cystic renal anomalies were reported in 4 babies (1.2%), and 10 children (3.1%) were reported to have other renal anomalies, including duplex kidneys or a single kidney. A total of 240 babies with congenital hydronephrosis were followed up. Hydronephrosis resolved in 99 children (41.2%) within 2 months of birth. A total of 29 subjects had underlying renal anomalies (12.1%), including vesicoureteral reflux (n=12, 5%), pelvi-ureteric junction obstruction (n=14, 5.8%), and posterior urethral valve (n=3, 1.3%). The best predictor for nonresolving congenital hydronephrosis and underlying anatomical abnormalities was the anteroposterior diameter on the first postnatal scan. A cut-off point of 5 mm was found to be 83% sensitive in predicting nonresolving hydronephrosis, while 7 mm was 88% sensitive and 10 mm was 94% sensitive.

CONCLUSIONS

Congenital hydronephrosis is the commonest ADUTA. A large percentage resolved within 2 months of birth, but underlying anatomical abnormalities were found in 12.1%. All babies with antenatally detected hydronephrosis should be examined by ultrasound postnatally but further radiological investigations should only be performed for persistent significant AP dilatation >=10 mm.

The antenatally detected pelvi-ureteric junction stenosis: advances in renography and strategy of management

This review includes an analysis of new developments in the field of renography, the predictive factors suggesting the need for pyeloplasty in cases of pelvi-utereric stenosis detected antenatally and integration of the pelvi-ureteric junction stenosis within the framework of antenatally detected hydronephrosis.

Revised guidelines on management of antenatal hydronephrosis

Widespread antenatal screening has resulted in increased detection of anomalies of the kidneys and urinary tract. The present guidelines update the recommendations published in 2000. Antenatal hydronephrosis (ANH) is transient and resolves by the third trimester in almost one-half cases. The presence of oligohydramnios and additional renal or extrarenal anomalies suggests significant pathology. All patients with ANH should undergo postnatal ultrasonography; the intensity of subsequent evaluation depends on anteroposterior diameter (APD) of the renal pelvis and/or Society for Fetal Urology (SFU) grading. Patients with postnatal APD exceeding 10 mm and/or SFU grade 3-4 should be screened for upper or lower urinary tract obstruction and vesicoureteric reflux (VUR). Infants with VUR should receive antibiotic prophylaxis through the first year of life, and their parents counseled regarding the risk of urinary tract infections. The management of patients with pelviureteric junction or vesicoureteric junction obstruction depends on clinical features and results of sequential ultrasonography and radionuclide renography. Surgery is considered in patients with increasing renal pelvic APD and/or an obstructed renogram with differential renal function <35-40% or its subsequent decline. Further studies are necessary to clarify the role of prenatal intervention, frequency of follow-up investigations and indications for surgery in these patients.

Diagnostic accuracy of renal pelvic dilatation for detecting surgically managed ureteropelvic junction obstruction

PURPOSE

In this study we evaluate the diagnostic accuracy of renal pelvic dilatation for detecting infants with prenatal hydronephrosis who will need surgical intervention for ureteropelvic junction obstruction during followup.

MATERIALS AND METHODS

Between 1999 and 2010, 371 newborns diagnosed with isolated prenatal hydronephrosis were prospectively followed. The main event of interest was the need for pyeloplasty. Diagnostic odds ratio, sensitivity, specificity and diagnostic accuracy (assessed by AUC) of fetal renal pelvic dilatation and postnatal renal pelvic dilatation were evaluated.

RESULTS

A total of 312 patients were included in the analysis and 25 (7.5%) infants underwent pyeloplasty. The diagnostic performance for detecting the need for pyeloplasty was excellent for all ultrasonography measurements. The AUC was 0.96 (95% CI 0.92-0.98) for fetal renal pelvic dilatation, 0.97 (95% CI 0.95-0.98) for postnatal renal pelvic dilatation and 0.95 (95% CI 0.92-0.97) for the Society for Fetal Urology grading system. A cutoff of 18 mm for fetal renal pelvic dilatation and a cutoff of 16 mm for postnatal renal pelvic dilatation had the best diagnostic odds ratio to identify infants who needed pyeloplasty. Considering a diagnosis to be positive only if fetal renal pelvic dilatation was greater than 18 mm and postnatal dilatation was greater than 16 mm, sensitivity was 100% and specificity was 86% (95% CI 80.7-89.9).

CONCLUSIONS

Our findings suggest that the combination of fetal and postnatal renal pelvic dilatation is able to increase the diagnostic accuracy for detecting infants who need a more comprehensive postnatal investigation for upper urinary tract obstruction.

Postnatal evaluation of intrauterine hydronephrosis due to ureteropelvic junction obstruction

PURPOSE: Fetal hydronephrosis is a frequent finding due to advances in prenatal ultrasonography. The definition of fetal and neonatal urinary tract obstruction is a very difficult task requiring confirmation of reduced renal function and hydronephrosis. In this study we followed a series of consecutive patients with intrauterine hydronephrosis that persisted during post-natal life. METHODS: 116 newborns with antenatal hydronephrosis diagnosed by ultrasound and submitted to a specific post-natal evaluative protocol with a follow-up period of 6 years. RESULTS: In 45 (38.8%) of 116 patients, ureteropelvic junction (UPJ) obstruction was confirmed and surgical correction of the UPJ obstruction was done in 19 patients. From 26 children who were initially submitted to non-surgical treatment, only 6 (23%) needed a surgical approach during follow up. Overall analysis showed that surgery was performed in 25 patients with UPJ obstruction, and the others 20 patients were kept under clinical observation, since normal renal function was confirmed by scintigraphy scans. CONCLUSION: Fetal hydronephrosis due to UPJ obstruction deserves careful postnatal evaluation. UPJ obstruction is the most frequent anomaly and its surgical treatment has very precise indications. The evaluative protocol was useful in identify patients that could be followed-up with a non-surgical approach.

Feasibility of measuring 3-dimensional renal parenchymal volume to predict postnatal renal function in near-term fetuses with congenital hydronephrosis: a preliminary study

OBJECTIVES

The purposes of this study were to evaluate the feasibility of predicting kidney function using the fetal renal parenchymal volume as determined by prenatal 3-dimensional (3D) sonography and to determine the association among the prenatal renal pelvic diameter, renal parenchymal volume, and postnatal renal function in near-term fetuses with unilateral hydronephrosis.

METHODS

This retrospective study included 42 kidneys (21 normal and 21 hydronephrotic) from 21 fetuses between 30 and 39 weeks' gestation. We used the extended imaging virtual organ computer-aided analysis (XI VOCAL; 10 planes) technique for the prenatal volumetric measurements, and postnatal renal function was estimated using renal scintigraphy. An independent-samples Student ttest, Spearman's rank correlation, and simple linear regression were used for the statistical analyses. Reproducibility was confirmed with a paired Student t test and intraclass correlation coefficients.

RESULTS

The renal pelvic diameter correlated well with the renal parenchymal volume Spearman ρ = 0.765; P < .001). The postnatal renal function correlated with the adjusted 3D renal parenchymal volume (Spearman ρ = -0.321; P = .043) but did not correlate with the prenatal renal pelvic diameter (Spearman ρ = -0.291; P = .062).

CONCLUSIONS

This preliminary study showed that 3D renal parenchymal volume could be a coparameter for predicting postnatal renal function with the renal pelvic diameter. Further studies in a larger population are required to obtain robust results.

Clinical spectrum of antenatally detected urinary tract abnormalities with respect to hydronephrosis at postnatal ultrasound scan

AIM

The purpose of this study was to compare the outcome of infants having antenatally detected urinary tract abnormalities (AUTAs) with respect to the presence of hydronephrosis in postnatal ultrasonography (US) examination.

PATIENTS AND METHODS

Between January 1999 and October 2009, 256 infants diagnosed with AUTAs were prospectively followed. Infants were divided into two groups according to the presence of hydronephrosis in postnatal US examination: Group 1, infants with hydronephrosis; Group 2, infants without hydronephrosis (including renal cyst, agenesis, ectopic kidney). The events of interest were the presence and diagnoses of uropathy, AUTA resolution, urinary tract infection (UTI), development of renal parenchymal defects (RPDs)--focal or global scarring, dysplasia--, acute kidney injury (AKI) and chronic kidney disease (CKD), and the need for surgery and dialysis treatment.

RESULTS

The most commonly detected underlying abnormalities were ureteropelvic junction obstruction (44.8 %), vesicoureteral reflux (VUR) (30.0 %) and megaureter (9.5 %) in patients with postnatal hydronephrosis. On the other hand, multicystic dysplastic kidney (43.5 %), renal agenesis (19.4 %) and VUR (19.4 %) were mostly encountered abnormalities in patients without postnatal hydronephrosis. RPDs were significantly more common among patients with postnatal hydronephrosis compared to those without hydronephrosis (37 vs. 21 %, P = 0.02). The incidence of UTI and VUR was higher in infants with postnatal hydronephrosis than in infants without hydronephrosis. There was no statistically significant difference in terms of the development of AKI and CKD and the need for surgery and dialysis treatment between patients with hydronephrosis and those without hydronephrosis.

CONCLUSION

Infants with AUTAs should be investigated postnatally. The findings from this study will help to identify the natural history and outcome of infants with AUTAs according to the postnatal US parameters.

Clinical course of 822 children with prenatally detected nephrouropathies

BACKGROUND AND OBJECTIVES

With the advent of fetal screening ultrasonography, the detection of congenital anomalies of the kidney and urinary tract (CAKUT) in utero has permitted early management of these conditions. This study aims to describe the clinical course of a large cohort of patients with prenatally detected nephrouropathies.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this retrospective cohort study, 822 patients were prenatally diagnosed with CAKUT and systematically followed up at a tertiary Renal Unit for a median time of 43 months. Variables included in the analysis were sex, laterality, fetal ultrasonography (isolated versus associated hydronephrosis), and presence/absence of nephrouropathies. The events of interest were urinary tract infection, surgical interventions, hypertension, CKD, and death. Survival analyses were performed to evaluate time until occurrence of the events of interest.

RESULTS

Urinary tract infection occurred in 245 (29.8%) children, with higher risk in females (hazard ratio=1.30, 95% confidence interval=1.02-1.70, P=0.05); 22 patients (2.7%) had hypertension, and 49 (6%) patients developed CKD. The risk of CKD was greater in patients with associated hydronephrosis (hazard ratio=5.20, 95% confidence interval=2.90-9.30, P<0.001). Twelve patients (1.5%) died during follow-up. Death was significantly associated with being born during the first period of the study (hazard ratio=6.00, 95% confidence interval=1.60-22.50, P<0.001), associated hydronephrosis (hazard ratio=9.30, 95% confidence interval=2.90-29.30, P<0.001), and CKD (hazard ratio=170.00, 95% confidence interval=41.00-228.00, P<0.001).

CONCLUSIONS

In our series, the clinical course of prenatally detected CAKUT was heterogeneous, and those infants with associated hydronephrosis at baseline were identified as a high-risk subgroup.

Antenatal ultrasonographic anteroposterior renal pelvis diameter measurement: is it a reliable way of defining fetal hydronephrosis?

Purpose. It was to quantify the intraobserver and interobserver variability of the sonographic measurements of renal pelvis and classify hydronephrosis severity. Methods. Two ultrasonographers evaluated 17 fetuses from 23 to 39 weeks of gestation. Renal pelvis APD were taken in 50 renal units. For intraobserver error, one of them performed three sequential measurements. The mean and standard deviation from the absolute and percentage differences between measurements were calculated. Bland-Altman plots were used to visually assess the relationship between the precision of repeated measurements. Hydronephrosis was classified as mild (5.0 to 9.9 mm), moderate (10.0 to 14.9 mm), or severe (≥15.0 mm). Interrater agreement were obtained using the Kappa index. Results. Absolute intraobserver variation in APD measurements was 5.2 ± 3.5%. Interobserver variation of ultrasonographers was 9.3 ± 9.7%. Neither intraobserver or interobserver error increased with increasing APD size. The overall percentage of agreement with the antenatal hydronephrosis diagnosis was 64%. Cohen's Kappa to hydronephrosis severity was 0.51 (95% CI, 0.33 to 0.69). Conclusion. Inter and intraobserver APD measurement errors were low in these group, but the agreement to hydronephrosis diagnosis and classification was fair. We suggest that standard and serial APD measurement can better define and evaluate fetal hydronephrosis.

Variation among pediatric urologists and across 2 continents in antibiotic prophylaxis and evaluation for prenatally detected hydronephrosis: a survey of American and European pediatric urologists

PURPOSE

No clear practice guidelines exist to evaluate prenatally diagnosed hydronephrosis or recommend antibiotic prophylaxis. We hypothesized that among pediatric urologists there is significant variability in prenatal hydronephrosis evaluation and management.

MATERIALS AND METHODS

We created a survey questionnaire to answer certain questions, including 1) what prenatal parameters trigger postnatal evaluation, 2) how pediatric urologists manage prenatal hydronephrosis and 3) what are their recommendations for antibiotic prophylaxis. Survey questions included demographics and practice patterns, and influences concerning radiographic tests and prophylactic antibiotics. A Web based survey link was sent to members of the Urology Section, American Academy of Pediatrics and the European Society for Pediatric Urology. We received 156 responses. We also compared practices based in Europe in 60 respondents and in the United States in 70.

RESULTS

There was significant response variability to all questions answered with no question achieving a consensus of more than 50%. European and American respondents were equally distributed in regard to years in practice and number of patients per month. Radiographic factors influenced the decision to perform further imaging or provide prophylactic antibiotics in around 50% of respondents. There was wide variability in parameters triggering intervention and in prophylactic antibiotics. Pediatric urologists in practice more than 15 years were less likely to prescribe antibiotic prophylaxis at birth than those in practice less than 15 years. Variation also existed by geographic region with American physicians more likely to prescribe antibiotics for any prenatal hydronephrosis compared to their European counterparts (77% vs 40%, p <0.005) and European physicians more likely to be influenced by prenatal pelvic diameter when obtaining postnatal imaging (unilateral 70% vs 47%, p = 0.009 and bilateral 55% vs 36%, p = 0.03, respectively). European pediatric urologists were also more likely to order renal scans than their American counterparts. These differences were less significant for high grade hydronephrosis.

CONCLUSIONS

Even among pediatric urologists there is considerable variation in radiographic resource and prophylactic antibiotics use when managing prenatal hydronephrosis. Some variation may be explained by regional differences but it is most probably due to absent clear guidelines based on prospective, randomized, controlled trials.

Ultrasound score: a new method to differentiate fetal physiological and pathological hydronephrosis

OBJECTIVE

To determine whether the prenatal ultrasound (US) score can effectively differentiate fetal physiological and pathological hydronephrosis.

STUDY DESIGN

158 fetuses (198 kidneys) with hydronephrosis (PAPD>or=10mm) were diagnosed by prenatal US in the third trimester. We measured and recorded three US parameters: renal pelvic anterior posterior diameter (PAPD), renal parenchyma thickness and pelvicaliceal morphology. They were graded with a score from 0 to 3 on the basis of severity of hydronephrosis, and the total US score of each kidney was obtained. According to the postnatal US and clinical diagnosis and management, all the cases were divided into two groups: physiological and pathological hydronephrosis. Using receiver operating characteristic curves analysis, we researched whether the US score was more accurate than each parameter and which was the best cut-off value for differential diagnosis of physiological and pathological hydronephrosis.

RESULTS

Of all the 198 hydronephrosis, 139 (70.20%) were physiological and 59 (29.80%) were pathological confirmed postnatally. Area under the curve of US score was 0.982, which was significantly larger than that of each parameter (P<0.05). The higher the score, the higher the possibility of pathological hydronephrosis was. Score 6 was the best cut-off value: the sensitivity, specificity, positive predictive value, negative predictive value, consistency rate and Youden's index were 89.83%, 94.24%, 86.89%, 95.62%, 92.93% and 0.8407, respectively.

CONCLUSION

Prenatal US score is easy to obtain by measuring some data of the kidney and can effectively differentiate fetal physiological and pathological hydronephrosis. It can also be used as a new quantitative method to evaluate the prognosis of fetal hydronephrosis so as to provide reference for prenatal intervention and more accurate information for the family of the fetus.

Management in children of mild postnatal renal dilatation but without vesicoureteral reflux

Infants with mild postnatal renal dilatation but without vesicoureteral reflux pose a challenge. For how long and in what way should they be followed? From May 1989 to December 2006, we prospectively followed 1,795 pregnancies in which the foetal renal pelvis measured 4 mm or greater. Voiding cystourethrography (VCUG) and renal ultrasound were performed on 1,315 infants at 6 weeks of age. Our study group comprised 208 (167 male) infants with normal VCUG findings who had a renal pelvis of 6-11 mm. We followed them for 1-17 years (mean 11 years). Medical and radiological records were reviewed to determine any urinary symptoms and final outcome. They underwent, on average, four further imaging tests. The renal dilatation had resolved by 24 months in approximately 70%. Urinary tract infection (UTI) developed in 16 (8%). Calyceal dilatation was more likely in those developing UTI (P=0.02). Twenty-two (10.6%) had a radiologically demonstrated urinary tract abnormality. Of the five who had renal scarring or severe obstruction, four became symptomatic. Most infants with mild postnatal renal dilatation can be investigated with only one further sonogram at 24 months of age. Mild postnatal renal dilatation is associated with subsequent UTI or renal tract abnormality in 18%. Severe renal abnormality occurred in 2.4%.

[Imaging studies in infants and children with dilatation of the upper urinary tract]

Prenatally or postnatally diagnosed dilatation of the upper urinary tract initiates postnatal investigations, including sonography, dynamic renography (MAG 3) and optional voiding cystourethrography. The first ultrasound examination should be performed 3-5 days after birth and in urgent cases 10-12 h after delivery of the baby. Dynamic renography (MAG 3) is the standard diagnostic investigation and permits simultaneous assessment of renal perfusion and drainage. MRI combines excellent anatomical detail with functional information, without exposure to radiation but needs general anaesthesia in infants and younger children. Intravenous urography is no longer performed routinely in children with a dilated upper urinary tract. The combination of ultrasound and MAG 3 produces the necessary anatomical and functional information to follow the degree of obstruction and to decide between surgical intervention or a conservative follow-up.

CONGENITAL URINARY BLADDER OUTLET OBSTRUCTION

The term congenital ‘bladder outlet obstruction (BOO)’ describes the collection of conditions in which the normal, urethral egress of urine from the fetal bladder is impaired. The term is interchangeable with fetal ‘lower urinary tract obstruction’, as used by other authors. After considering normal urinary tract embryology, we describe the epidemiology of congenital BOO and the primary anatomical disorders associated with it. We then proceed to describe its fetal and postnatal clinical manifestations and then consider therapies and interventions which have been used to manage the condition. We not only focus on urethral and bladder disease with constitutes BOO itself, but also describe associated kidney disorders which, via chronic renal excretory failure, are important causes of morbidity. Rather than provide an exhaustive review, we emphasise studies published in the last decade, and therefore readers are referred to other reviews citing numerous earlier references.

Postnatal follow-up of antenatal hydronephrosis: a health-care challenge

OBJECTIVE

To examine our experience with ANH and to determine the success of our postnatal follow-up program.

STUDY DESIGN

Charts of mothers and infants seen (2004 to 2008) at our Regional Perinatal Center were reviewed retrospectively. ANH was defined during the third trimester by anterior pelvic diameters as follows: mild 7 to 9, moderate 10 to 14 or severe >or=15 mm. Fetuses with multicystic dysplastic kidney (MCDK) were included.

RESULT

Screening of approximately 15 000 ultrasound (US) reports identified 268 fetuses with ANH. After prenatal US surveillance, 88 (33%) fetuses had resolved, while 180 (67%) required postnatal follow-up. These 180 fetuses were diagnosed with mild 38 (21%), moderate 83 (46%) and severe 19 (11%) ANH, uni or bilateral hydroureters 12 (7%), MCDK 19 (10%) and miscellaneous 9 (5%). Postnatal follow-up was successfully established for 75% of infants with hydroureters, 68% for those with MCDK and for 37% of infants with mild, 53% with moderate and 58% with severe ANH. Factors commonly known to influence compliance were not found more frequently among the 91 infants who were lost to follow-up. The only positive predictor for postnatal follow-up was a prenatal consultation with the pediatric urologist.

CONCLUSION

Our antepartum program for diagnosis of ANH is accessible and efficient; however, there was an unacceptably high number of infants lost to follow-up. The absence of traditional barriers for compliance highlights the need to explore new ways of improving postnatal follow-up of infants with ANH.

Antenatal renal pelvis dilatation: 2-year follow-up with DMSA scintigraphy

The aim of this study was to determine whether a postnatal ultrasound (US) can detect infants with antenatal renal pelvis dilatation (ARPD) who run a minimal risk of renal damage 2 years after birth. The study cohort consisted of 14,000 pregnant women who consecutively underwent routine US examinations during the second trimester. Subsequent examinations were performed on the basis of obstetrical indications. In total, 106 foetuses were diagnosed with ARPD > or =5 mm. Two postnatal US were performed on the newborns: on postpartum days 5-7 and during the third week of life. The findings were considered to be normal when the renal pelvis diameter (RPD) was < or = 7 mm and when there was no calyceal or ureteric dilatation or signs of renal dysplasia or other anomalies. Voiding cystourethrography (VCUG) was done at 6-8 weeks after birth. When the children reached 2 years of age, renal status was evaluated with DMSA scintigraphy or, if not possible, US. In 53 of the 103 children available for evaluation, the postnatal US findings were normal; 49 of the 53 children were also given a DMSA, and the results were normal in all cases. An US scan (all normal) only was performed in three children because the families refused a DMSA. One family refused any form of examination at the 2-year follow-up. Based on our results, we conclude that postnatal US can detect infants who do not require follow-up assessments of renal development.

Antenatal hydronephrosis: infants with minor postnatal dilatation do not need prophylaxis

The aim of this study was to determine the occurrence of urinary tract infection (UTI) in infants with antenatal renal pelvis dilatation (ARPD). Consecutive ultrasound (US) screening of 14,000 pregnant women detected ARPD >or=5 mm in 106 foetuses. After birth, two US examinations were performed: on the fifth to seventh day and during the third week of life. The findings were considered normal when renal pelvis dilatation (RPD) was <or=7 mm on both examinations and no other signs of abnormality were present. Voiding cystourethrography (VCUG) was done in all infants 6-8 weeks after birth. One hundred and three infants were followed for 2 years. Antibacterial prophylaxis (trimethoprim 1 mg/kg per day) was given to those with RPD >or=15 mm, vesicoureteric reflux (VUR) grades III-V and suspected obstruction. In 53/103 babies, both US examinations were normal, three had VUR grade I. Two girls had UTI at 18 and 24 months of age, respectively. Among the 50 infants with abnormal initial US, six had VUR, of which four were high grade (IV-V). All four developed UTI. We conclude that UTI is uncommon in infants with two normal postnatal US examinations. Routine use of antibacterial prophylaxis in these infants therefore cannot be recommended.

Reproducibility of fetal renal pelvis volume measurement using three-dimensional ultrasound

OBJECTIVE

To assess the reproducibility of fetal renal pelvis volume measurement in hydronephrotic kidneys using transabdominal three-dimensional (3D) ultrasound.

METHODS

The fetal renal pelvis volume was measured using 3D ultrasound in one kidney in each of 15 fetuses with hydronephrosis in the second or third trimester of pregnancy. Hydronephrosis was diagnosed when the fetus had an anteroposterior renal pelvis diameter > or = 5 mm. After volume acquisition by one of the observers, the repeatability of volume calculation with manual delineation of the fetal renal pelvis was assessed by six different observers using the Virtual Organ Computer-aided AnaLysis (VOCAL(trade mark)) imaging program. The intraclass correlation coefficients (ICC), coefficient of variation (CV) and within- and between-observer repeatability coefficient (r) were calculated and Bland-Altman plots were constructed.

RESULTS

Both intra- and interobserver reliability of the fetal renal pelvis volume measurements were considered to be very good. For intraobserver reliability, the ICC was 0.996 and the CV was 10.8%. For the overall interobserver reliability, the ICC was 0.998 and the CV was 15.7%; the interobserver reliability between pairs of observers had ICCs between 0.994 and 0.999, and CVs between 19.5% and 7.6% for inexperienced and experienced observers, respectively.

CONCLUSION

With 3D ultrasound using the VOCAL imaging program, it is technically feasible to reproduce fetal renal pelvis volume measurements. Further research to establish the clinical applications of this technology is warranted.

Management of fetal hydronephrosis

Prenatally detected hydronephrosis has become a common diagnosis for both pediatric nephrologists and urologists. Hydronephrosis is most commonly assessed by the Society for Fetal Urology grading system or anterior-posterior diameter of the renal pelvis in the transverse plane. Some cases of bilateral obstruction, most commonly from posterior urethral valves, can be life-threatening and require close monitoring or, occasionally, fetal intervention. The majority are unilateral and of no threat to the growing fetus. The crux of postnatal management is the separation of the minority of patients whose renal function is at risk from the majority who will suffer no renal consequences. This management involves a regimen of ultrasounds, voiding cystourethrograms, and nuclear renograms for diagnosis and surveillance. Recent literature has been aimed at the timing and necessity of these studies in order to minimize extraneous studies without compromising renal function.

Outcome of isolated antenatal hydronephrosis: a prospective cohort study

The purpose of this study was to report the outcome of infants with antenatal hydronephrosis. Between May 1999 and June 2006, all patients diagnosed with isolated fetal renal pelvic dilatation (RPD) were prospectively followed. The events of interest were: presence of uropathy, need for surgical intervention, RPD resolution, urinary tract infection (UTI), and hypertension. RPD was classified as mild (5-9.9 mm), moderate (10-14.9 mm) or severe (>or=15 mm). A total of 192 patients was included in the analysis; 114 were assigned to the group of non-significant findings (59.4%) and 78 to the group of significant uropathy (40.6%). Of 89 patients with mild dilatation, 16 (18%) presented uropathy. Median follow-up time was 24 months. Twenty-seven patients (15%) required surgical intervention. During follow-up, UTI occurred in 27 (14%) children. Of 89 patients with mild dilatation, seven (7.8%) presented UTI during follow-up. Renal function, blood pressure, and somatic growth were within normal range at last visit. The majority of patients with mild fetal RPD have no significant findings during infancy. Nevertheless, our prospective study has shown that 18% of these patients presented uropathy and 7.8% had UTI during a medium-term follow-up time. Our findings suggested that, in contrast to patients with moderate/severe RPD, infants with mild RPD do not require invasive diagnostic procedures but need strict clinical surveillance for UTI and progression of RPD.

Is screening for vesicoureteral reflux mandatory in infants with antenatal renal pelvis dilatation?

AIM

To determine whether postnatal ultrasound (US) can guide the use of voiding cystourethrography (VCUG) in infants with antenatally detected renal pelvis dilatation (ARPD).

METHODS

14,000 pregnant women consecutively underwent routine US examination during the second trimester. US examinations later in pregnancy were performed as follow-up of previous anomalies or on obstetrical indications. One hundred and six fetuses with ARPD > or =5 mm were identified. Two postnatal US examinations were performed in the newborns: on the 5th to 7th day and during the 3rd week of life. The findings were considered normal when renal pelvis dilatation (RPD) was < or =7 mm on both US examinations, and no calyceal or ureteric dilatation or signs of renal dysplasia or other anomalies were present. VCUG was done 6 to 8 wk after birth.

RESULTS

In 53 of 103 analysable infants, the postnatal ultrasonographic findings were normal. The VCUG was abnormal in three of these 53 infants, all with vesicoureteral reflux (VUR) grade I. Of 50 infants who had abnormal US examinations, six had VUR, four of which were grade IV and V reflux.

CONCLUSION

In infants with ARPD who undergo two postnatal US examinations with RPD < or =7 mm and have no other abnormalities, VCUG is unnecessary.

[Fetal genitourinary anomalies Perinatal and postnatal management with imaging techniques]

Improvements in ultrasound technology and the appropriate timing of antenatal ultrasound has led to refined prenatal diagnosis and enhanced accuracy of diagnosis of fetal renal anomalies and makes it possible to treat obstructive and/or refluxing uropathies before the onset of clinical symptoms. The third trimester renal sonography is the most important to detect hydronephrosis amenable to treatment.Classically, the prenatal diagnosis of hydronephrosis, unilateral renal agenesis, or MDKD initiates postnatal investigations, including sonography, voiding cystourethrography (VCUG), and isotopic renography. The exact degree of renal pelvic dilatation that requires full postnatal investigation is still not entirely resolved. Most authors accept the upper limit of 7 mm for the AP diameter of the renal pelvis. The US examination should be performed after the physiological dehydration period, namely 3-5 days after birth, in an urgent case on the 1st day. A meticulous ultrasound examination performed by a physician who is familiar with the renal abnormalities shows the whole extent of underlying pathology. The role of MR urography in the work-up of renal anomalies, particularly of hydronephrosis, is currently being investigated. Due to the close developmental relationship of the urinary and genital tracts, malformations frequently occur in both of these systems. Therefore in all patients, especially in girls with renal anomalies (unilateral renal agenesis, multicystic dysplastic kidney disease), the internal genitalia need to be evaluated.

Insights into the pathogenesis and natural history of fetuses with renal pelvis dilatation

Fetal renal pelvis dilatation is a frequent abnormality that has been observed in 4.5% of pregnancies. The majority of these cases have a tendency to resolve during infancy. Nevertheless, fetal renal pelvis dilatation may be due to significant structural abnormalities such as pelvi-ureteric junction stenosis or vesico-ureteral reflux that may adversely affect renal function or cause urinary infection or sepsis. This review article aims to summarize the data regarding fetal renal pelvis dilatation and to analyze controversial attitudes in the light of the various lines of practice, and to present rational antenatal and postnatal investigation strategy.