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

Prenatal ultrasound and urological anomalies

Prenatal ultrasound is an integral part of caring for pregnant women in the United States. Although surprisingly few data exist to support the clinical benefit of screening ultrasound during pregnancy, its use continues to rise. Urologic anomalies are among the most commonly identified, with overall detection sensitivity approaching 90%. Prenatal hydronephrosis is the most frequently identified finding and predicting postnatal pathology based on its presence can be difficult. As the degree of fetal hydronephrosis increases so does the risk of true urinary tract pathology. Diagnoses that require more urgent care include causes of lower urinary tract obstruction and bladder and cloacal exstrophy.

Natural history of bilateral mild isolated antenatal hydronephrosis conservatively managed

BACKGROUND

The purpose of this study was to assess the prevalence and outcome of newborns with bilateral mild isolated antenatal hydronephrosis managed with neither antibiotic prophylaxis nor voiding cystourethrography (VCUG).

METHODS

Inclusion criteria were ultrasonographic evidence of an anterior-posterior pelvic diameter (APPD) of 5-15 mm at the third trimester of gestation and on the first postnatal ultrasound sonogram. Exclusion criteria were an APPD >15 mm, calyectasis, hydroureteronephrosis, or renal or bladder abnormalities. Ultrasound follow-up was performed. Parents were familiarized with the signs of urinary tract infection (UTI). If UTI was confirmed, VCUG was performed. The outcome was assessed as intrauterine resolution of hydronephrosis, total or partial resolution, stability, or progression.

RESULTS

Hydronephrosis was bilateral in 98 of the 236 newborns (196 hydronephrotic kidneys) with mild isolated antenatal hydronephrosis enrolled in this study. Nine patients had UTI, and none showed reflux. After a mean follow-up of 15 months, 74 kidneys showed intrauterine resolution (38%), 82 (42%) showed total resolution, 13 showed partial resolution, 24 were stable, and 3 showed progression. Bilateral cases represented 42% of mild isolated antenatal hydronephrosis. During the first year of life, 80% of the kidneys showed total hydronephrosis resolution, 9% of patients had UTI, and none of the patients showed reflux.

CONCLUSIONS

Antibiotic prophylaxis and VCUG are not mandatory in newborns with bilateral mild isolated antenatal hydronephrosis, but clinical and ultrasound follow-up are recommended during the first year of life.

Screening high-grade vesicoureteral reflux in young infants with a febrile urinary tract infection

BACKGROUND

The lack of good evidence for improved outcomes in children and young infants with febrile urinary tract infection (UTI) after aggressive treatment for vesicoureteral reflux (VUR) has raised doubts regarding the need for routine voiding cystourethrography (VCUG), and the appropriate imaging evaluation in these children remains controversial.

OBJECTIVES

This prospective study aimed to determine whether abnormalities found on acute dimercaptosuccinic acid (DMSA) scan and ultrasound (US) can help indicate the necessity of voiding cystourethrography (VCUG) in young infants.

METHODS

For 3.5 years, all infants younger than 3 months presenting with first febrile UTI were prospectively studied. All infants were hospitalized and investigated using US (<3 days after admission), DMSA scan (<5 days after admission), and VCUG (7-10 days after antibiotic treatment) after diagnosis. The association among findings of US, DMSA scan, and VCUG were evaluated.

RESULTS

From 220 infants, there were abnormal results in 136 (61.8%) US and in 111 (50.5%) DMSA scans. By US, ten infants (4.5%) with abscess or structural abnormalities other than VUR were diagnosed. High-grade (III-V) VUR was present in 39 patients (17.7%). The sensitivities for high-grade VUR of renal US alone (76.9%) or DMSA scan alone (82.1%) were not as good as that of the "OR rule" strategy, which had 92.3% sensitivity and 94.3% negative predictive value.

CONCLUSIONS

To screen high-grade VUR in young infants with febrile UTI, US and acute DMSA scan could be performed first. VCUG is only indicated when abnormalities are apparent on either US or DMSA scan or both.

Short-term outcome of mild isolated antenatal hydronephrosis conservatively managed

OBJECTIVES

To assess the outcome of newborns with mild isolated antenatal hydronephrosis (MIAHN) managed with neither antibiotic prophylaxis nor voiding cystourethrography (VCUG).

INCLUSION CRITERIA

anterior-posterior pelvic diameter 5-15 mm at third trimester of gestation, confirmed by first postnatal ultrasound.

EXCLUSION CRITERIA

pelvic diameter > 15 mm, calyectasis, hydroureteronephrosis, renal or bladder abnormalities. Clinical and ultrasound follow-up was performed. Parents were familiarized with urinary tract infection (UTI) signs. If UTI was confirmed, VCUG was performed. Hydronephrosis outcome was assessed as intrauterine resolution, total or partial resolution, stability or progression.

RESULTS

MIAHN was detected in 193 newborns (109 unilateral, 84 bilateral; 277 renal units); 23 (12%) had UTI and 2 of them showed low-grade reflux. After a mean follow-up of 15 months, 91 renal units showed intrauterine resolution (33%), 111 (40%) total resolution, 20 (7%) partial resolution, 52 (19%) stability and 3 (1%) progression.

CONCLUSION

Total resolution of hydronephrosis was observed in 73% of renal units during the first year. Routine antibiotic prophylaxis and VCUG might not be necessary in all infants with MIAHN, clinical and ultrasound follow-up being advisable during the first year of life.

Prediction of the outcome of antenatally diagnosed hydronephrosis: a multivariable analysis

PURPOSE

The majority of cases of antenatal hydronephrosis (ANH) resolve postnatally. The purpose of this study was to determine independent predictors for resolution of ANH using a multivariable analysis model.

METHODS

A retrospective study was performed on 100 children (80 males and 20 females, 118 renal units) referred to a single pediatric urology clinic with the diagnosis of ANH. Patients with ultimately resolved ANH were compared to unresolved cases in a univariate analysis in terms of sex, laterality, severity of ANH using Society for Fetal Urology (SFU) grading, antero-posterior pelvic diameter (APD), parenchymal thickness, renographic differential function and development of clinical complications, followed by a Cox proportional hazard model for multivariable analysis.

RESULTS

Median follow up was 34 months (range 3-204). Hydronephrosis in 62 units resolved spontaneously and pyeloplasty was done in 29. The remaining 27 units had persistent uncomplicated hydronephrosis at last follow up. Multivariate analysis showed larger APD (hazard ratio 0.54; 95%CI 0.36-0.80) and SFU grade 4 (HR 0.34; 95%CI 0.13-0.90) to be associated with a significantly lower likelihood of resolution. The mean initial APD in resolved cases was 9.4mm as opposed to 29.0mm in cases requiring surgery.

CONCLUSION

Large initial APD has predictive value for surgical intervention. This model is helpful in counseling families about the potential outcomes of ANH.

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.

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.

Urine IL-8 concentrations in infectious and non-infectious urinary tract conditions

Urine IL-8 concentrations are known to be elevated in urinary tract infection (UTI), as well as in vesicoureteral reflux (VUR) even in the absence of infection. In this study we further investigated urine IL-8 in infants with congenital anomalies of the kidneys and urinary tract and with antenatally diagnosed isolated pelvic dilatation. Urine IL-8 was measured in 159 infants aged 1 month to 1 year with acute UTI (group A, n = 26), resolved UTI (group B, n = 16), VUR without recent UTI (group C, n = 44), non-VUR congenital urinary anomalies without recent UTI (group D, n = 30), isolated antenatal pelvic dilatation (group E, n = 14) and in infants without known urinary tract condition (control group F, n = 29). Median values of urine IL-8/creatinine levels were 61.5, 4.64, 15.5, 14.3, 1.06 and 4.19 pg/μmol in groups A, B, C, D, E and F respectively. Compared with the control group, urine IL-8 was elevated in infants with acute UTI, VUR without acute UTI and congenital anomalies without acute UTI (p < 0.0001; p < 0.005; and p = 0.027 respectively), but not in infants with resolved UTI or with antenatal pelvic dilatation. Urine IL-8 levels are elevated in a variety of infectious and non-infectious urinary tract conditions, and hence may serve as a sensitive but not specific screening biomarker of urinary tract diseases.

Noninvasive assessment of antenatal hydronephrosis in mice reveals a critical role for Robo2 in maintaining anti-reflux mechanism

Antenatal hydronephrosis and vesicoureteral reflux (VUR) are common renal tract birth defects. We recently showed that disruption of the Robo2 gene is associated with VUR in humans and antenatal hydronephrosis in knockout mice. However, the natural history, causal relationship and developmental origins of these clinical conditions remain largely unclear. Although the hydronephrosis phenotype in Robo2 knockout mice has been attributed to the coexistence of ureteral reflux and obstruction in the same mice, this hypothesis has not been tested experimentally. Here we used noninvasive high-resolution micro-ultrasonography and pathological analysis to follow the progression of antenatal hydronephrosis in individual Robo2-deficient mice from embryo to adulthood. We found that hydronephrosis progressed continuously after birth with no spontaneous resolution. With the use of a microbubble ultrasound contrast agent and ultrasound-guided percutaneous aspiration, we demonstrated that antenatal hydronephrosis in Robo2-deficient mice is caused by high-grade VUR resulting from a dilated and incompetent ureterovesical junction rather than ureteral obstruction. We further documented Robo2 expression around the developing ureterovesical junction and identified early dilatation of ureteral orifice structures as a potential fetal origin of antenatal hydronephrosis and VUR. Our results thus demonstrate that Robo2 is crucial for the formation of a normal ureteral orifice and for the maintenance of an effective anti-reflux mechanism. This study also establishes a reproducible genetic mouse model of progressive antenatal hydronephrosis and primary high-grade VUR.

Prenatal ultrasonography: implications for pediatric urology

Prenatal ultrasonography has become a critical and integral component of the obstetric care of women worldwide. As a result, a number of congenital anomalies are now routinely being detected prior to birth. Anomalies affecting the genitourinary system are among those most commonly detected, and thus pediatric urologists are increasingly being asked to provide parental counseling in such situations. However, much of the data needed to enhance these discussions and provide informed consent are absent from the literature. In this review, we hope to address the published literature describing the rapidly expanding role of ultrasound in prenatal care. More importantly, however, we hope to provide some insight into the manner in which prenatal ultrasound and subsequent urologic anomaly diagnosis has affected the practice of pediatric urology.

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.

Fetal genitourinary anomalies--a pictorial review with postnatal correlation

An accurate diagnosis of fetal genitourinary abnormality is essential because some genitourinary abnormalities are associated with pulmonary hypoplasia, which ultimately affects the neonatal outcome. Adrenal masses are rare; however, presence of any lesion located at the superior pole of the kidney should raise the possibility of an adrenal mass. Fetal genital anomalies are rare as well and some of the most difficult to diagnose. A combination and pattern of findings allows for specific diagnosis of renal tract abnormalities. This article reviews the imaging appearance of fetal genitourinary abnormalities with perinatal imaging correlation where available.

Pediatric urologic conditions, including urinary infections

Genitourinary complaints are common in children, and the busy primary care provider must determine initial treatment and assess need for specialty referral. Many complaints are self-limited, but some represent disorders that can threaten organ function. In this article, an initial approach in the primary care office and a guide to specialty referral for pediatric urologic conditions of the urinary tract, male genitalia, and female genitalia are suggested.