Ultrasonography of hydronephrosis in the newborn: a practical review

The Diagnostic Efficacy of and Requirement for Postnatal Ultrasonography Screening for Congenital Anomalies of the Kidney and Urinary Tract

BACKGROUND

We aimed to investigate the efficacy of postnatal ultrasonography in detecting congenital anomalies of the kidneys and urinary tract in term infants without prenatal history of congenital anomalies of the kidneys and urinary tract.

METHODS

In this retrospective cohort study, we reviewed the records of term infants between six weeks and three months of age who underwent urinary tract ultrasonography during routine pediatric care.

RESULTS

Congenital anomalies of the kidneys and urinary tract were detected on prenatal ultrasonography in 75 of the 2620 patients included in the study. Congenital anomalies of the kidneys and urinary tract were detected via postnatal USG in 46 (1.8%) of 2554 patients without anomalies on prenatal USG screening. The most common anomaly was hydronephrosis (69.6%). Thirty-two cases of hydronephrosis, three cases of renal agenesis, four cases of horseshoe kidney, one case of MCDK, and two cases of duplex systems which were not detected on prenatal USG were detected on postnatal USG. On the other hand, 29 (1.1%) cases with mild or moderate hydronephrosis on prenatal ultrasonography did not have hydronephrosis on postnatal ultrasonography.

CONCLUSIONS

In our study, approximately one-third of the cases of hydronephrosis, unilateral renal agenesis, duplex systems, horseshoe kidney, and ectopic kidney were not detected in prenatal ultrasonography screening. Therefore, we believe that in addition to prenatal ultrasonography screening, postnatal ultrasonography screening of all children for urinary tract anomalies would be beneficial.

COMPARISON OF LAPAROSCOPIC AND OPEN PYELOPLASTY IMPACT ON COMFORT AND SUCCESS: A RETROSPECTIVE, SINGLE CENTER STUDY

Ureteropelvic junction obstruction causes hydronephrosis and may lead to renal parenchymal damage unless timely diagnosed and treated. Although open pyeloplasty is still the gold standard, it needs to be compared with new techniques. In this study, we compared laparoscopic and open pyeloplasty. Data on 113 patients who had undergone surgery between 2008 and 2014 were evaluated retrospectively. Thirty-nine patients had undergone laparoscopic pyeloplasty, and 74 had undergone open pyeloplasty. Ultrasonography was performed at 3 months and scintigraphy at 6 months postoperatively. Parameters such as the length of surgery, need for analgesics, length of hospital stay, complications, and success rates were compared. When compared to open pyeloplasty (mean 9.8 dexketoprofen 50 mg IV dose), the need for an analgesic was significantly lower in the laparoscopic pyeloplasty (mean 4.5, paracetamol 15 mg/kg IV dose) group (p<0.05). The length of hospital stay was also shorter in the laparoscopic pyeloplasty group (mean 4.0 days) than in the open pyeloplasty group (mean 7.3 days) (p<0.05). This study demonstrated that laparoscopic pyeloplasty could be safely used in the treatment of ureteropelvic junction obstruction with a lower need for analgesics and a shorter length of hospital stay than with open pyeloplasty.

Ultrasonography Results in First Urinary Tract Infection During Childhood: Which Age Group Should Be Screened?

OBJECTIVES

To determine the frequency of urinary system anomaly in children aged 0-18 y suffering from first urinary tract infection (UTI) and to establish which age group requires urinary ultrasonography (USG) screening.

METHODS

Age and gender, urine culture, urinary USG, and urological imaging results among 247 children in the 0-18 y age group with a first diagnosis of UTI were investigated retrospectively.

RESULTS

Anomaly was detected at USG in 68 (27.5%) of the 247 patients suffering from first UTI. The most common anomaly was hydronephrosis. Non-E. coli micro-organisms were the pathogenic agents in 61.8% of patients with anomalies detected at USG. Being in the 0-5 y age group (OR: 0.524, 95% CI 0.284-0.970, p = 0.040) and presence of atypical UTI (OR: 4.746, 95% CI: 1.675-13.450, p = 0.003) emerged as independent predictive markers of severe urinary system pathologies on multiple regression analysis.

CONCLUSION

Based on the data in the present study, routine USG screening is recommended for children suffering from first UTI under the age of 5 y and for the children suffering from atypical UTI at all ages.

Ultrasound and alternative multimodality imaging of intra-abdominal and pelvic cystic masses in the newborn

Introduction: Ultrasound is used commonly to detect and diagnose intra-abdominal and pelvic cystic masses in the newborn as it is easily available, relatively low cost, and non-invasive. Discussion: The diagnosis can be made or narrowed down by determining the location, size, sonographic features, organ involvement, and internal vascularity. The differential diagnoses include hydronephrosis, multicystic dysplastic kidney, adrenal haemorrhage, cystic teratomas, ovarian cysts, enteric cysts, meconium cysts, and liver haemangiomas. With the appropriate radiological knowledge, the ultrasound practitioner can help obtain an accurate diagnosis. Conclusion: This pictorial essay will familiarise the reader with the different common causes of intra-abdominal and pelvic masses detected on ultrasound through a wide range of conditions. The role of ultrasound in the evaluation of these conditions will be discussed and alternative imaging correlates will be offered.

Etiology of Hydronephrosis in adults and children: Ultrasonographic Assessment in 233 patients

Objectives:

Hydronephrosis (HN) is dilatation of the collecting system of the kidney due to obstruction of urine outflow. This study intended firstly, to investigate the efficacy of ultrasound (US) imaging to determine the cause of HN, and secondly, to list the causes of HN.

Methods:

In this retrospective study, 233 patients with HN were scanned to determine the cause of the HN in the period from 1^st January 2016 to 31^st October 2017. Categorical results were written as frequencies and percentages.

Results:

Out of 233, 91.41% were adults and 8.58% were children (P<0.001), 66.10% were male and 33.90% were female (P<0.001). In 55.36%, HN was in the right kidney and 44.64% was in the left (P=0.116). Exactly 58% of patients were suffering from grade-2, 21.5% grade-3, 11.6% grade-1, and 8.2% grade-4 HN. US imaging can determine the cause of HN in 70.4% of patients. Kidney or ureteric calculi were the cause of HN in 54.1% of cases, reflux was in 7.3%, and pelviureteric junction (PUJ) stenosis was in 3.9%.

In cases of calculi induced HN, 25.3% of the calculi were in the vesicoureteric (VUJ) junction, 21.5% were in the renal pelvis, 6.4% were in the PUJ or upper ureter, and only 0.9% were in the middle ureter.

Conclusion:

Ultrasound imaging can determine the cause of HN in more than two thirds of patients. Calculi are the most common cause of HN even in children and are most common in the VUJ junction.

Comparing predictive values of carbohydrate antigen 19-9, neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1 in 161 patients with ureteropelvic junction obstruction

BACKGROUND

To evaluate and compare the efficacy of urinary carbohydrate antigen 19-9 (CA19-9), neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1) biomarkers as predictive factors to determine the surgery requirement in patients with ureteropelvic junction obstruction.

METHODS

We obtained urine samples from 161 patients at diagnosis and evaluated their levels of the three biomarkers. The patients were under observation for 2 years; subsequently, they were divided into two groups based on their requirement of pyeloplasty. We determined the correlation between the urinary concentration of the biomarkers and surgical interventions, as well as the kidney function deterioration and sonography outcomes.

RESULTS

The non-surgery group included 60 male and 22 female patients with mean age of 21 months. The surgery group comprised 58 boys and 21 girls with mean age of 26.9 months with no significant difference of age and gender between the two groups. The outcomes were indicative of higher efficacy of CA19-9 level with a sensitivity and specificity of 84.2% and 73.2% at the cutoff point of 59.09 U/ml. Also, a significant negative correlation was detected between the kidney function and the concentrations of CA19-9 and NGAL.

CONCLUSIONS

Our evaluations demonstrate the higher efficacy of CA19-9 to predict the requirement of surgical intervention in comparison with the other biomarkers, as well as a significant correlation between kidney function deterioration and urinary CA19-9 and NGAL. The outcomes of this investigation could pave the way for more extensive clinical application of these urinary biomarkers, besides future research determining the association between markers and kidney fibrosis.

Role of Antibiotic Prophylaxis in the Management of Antenatal Hydronephrosis, Vesicoureteral Reflux, and Ureterocele in Infants

Widespread prenatal screening has resulted in increased detection of anomalies of the kidneys and urinary tract. Antenatal hydronephrosis (AHN) and vesicoureteral reflux (VUR) are among the most common congenital anomalies diagnosed in utero or after birth. Pediatric urologists frequently rely on continuous antibiotic prophylaxis (CAP) for managing AHN, VUR, and ureterocele, unless definitive treatment is performed. The main aim of antibiotic prophylaxis (ABP) is to prevent urinary tract infection and long-term complications. Nevertheless, the efficacy of ABP has been a source of considerable debate, and pediatricians have varied opinions on who would benefit from ABP. In this review article, we searched the currently available literature, for evidence of the role of ABP in the setting of AHN, VUR, and ureterocele. Most of our studies showed a limited benefit of ABP for HN and VUR. The data on the use of CAP in the management of ureterocele is scarce. However, due to the involvement of independent risk factors and other variables, a conclusion cannot be drawn from these studies alone. Pediatric urologists are urged to conduct randomized controlled trials to compare patients followed up with and without ABP. Given the lack of guidelines, an individualized approach should be used for the use of ABP, until precise guidelines and recommendations are developed.

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.

Renal Arterial Doppler Resistive Index in Differentiating Obstructive and Non-Obstructive Hydronephrosis in Children at Tikur Anbessa Specialized Hospital, Ethiopia, October, 2018

BACKGROUND

Most congenital anomalies of the urinary tract present with hydronephrosis. Some are physiological while others pathological. Ultrasound, micturating cyst urethrography, dynamic renal scintigraphy, intravenous urography, dynamic and static magnetic resonance urography are used for examination. Currently, renal arterial Doppler resistance index is used as complimentary mechanism. This study assesses our experience in resistive index measurement in differentiating obstructive from non-obstructive hydronephrosis in children.

METHODS

A cross-sectional study of forty-two infants and children (<14 years) with hydronephrosis were enrolled using consecutive sampling. Ultrasonography to assess the degree of hydronephrosis and avoiding cystourethrogram were used for the diagnosis of vesicoureteral reflux and posterior urethral valve. Intravenous urogram and surgery were used to confirm causes for obstructive hydronephrosis. Doppler ultrasonography assessed both kidneys to determine mean resistive index for both obstructive and non-obstructive hydronephrosis as well as nonobstructive kidneys. Independent t test was used for analysis at p< 0.005.

RESULTS

The major cause for obstructive hydronephrosis was pelviuretheric junction obstruction (47.6%) followed by posterior urethral valve (16.7%). For non-obstructive hydronephrosis, vesicoureteral reflux was the main cause followed by prune belly syndrome. The mean resistive index for non-hydronephrotic kidneys was 0.6654 ±0.053, for nonobstructive hydronephrotic ones was 0.6825 ± 0.06668 and obstructive ones was 0.7791 ± 0.11977. The mean resistive index difference between the obstructive and non-obstructive hydronephrosis was 0.09661 with standard error of difference 0.02443. The difference was statistically significant (P-<0.001). A mean RI ROC curve showed sensitivity, specificity and accuracy of 71.1%, 81.2%, 75.4% respectively (p=0.003).

CONCLUSION

This study has shown that the mean renal arterial resistive index was significantly higher in obstructive hydronephrotic kidneys than non-obstructive hydronephrotic kidneys. This can be a valuable tool for diagnosis and follow-up after intervention.

Optimal Timing of Spinal Ultrasound Evaluations for Sacral Dimples in Neonates: Earlier May Not Be Better

OBJECTIVES

A spinal ultrasound (US) evaluation during the immediate postnatal period may have limited ability in evaluating filum thickness because of the spinal cord pulsation caused by a crowded subarachnoid space and the cerebrospinal fluid deficiency during this period. This study aimed to determine the optimal timing of spinal US to evaluate sacral dimples in neonates.

METHODS

This study included 585 neonates who had a clinically suspicious sacral dimple and underwent spinal US examinations between January 2015 and August 2017. Patients were classified into 1 of 2 groups based on whether measurements of all parameters were possible (group A) or not (group B). Neonatal and maternal clinical factors, including the antenatal history and US parameters, were compared between groups.

RESULTS

Group A included 443 patients, and group B included 82. Patients in group B were significantly younger (6.2 versus 31.0 days), had a younger corrective age (38.9 versus 42.5 weeks), and had a smaller body weight (3.1 versus 4.6 kg) than those in group A (all P < .005). However, no statistically significant differences were found in other patient or maternal factors (P > .05 for all). The pulsation of the conus medullaris and nerve roots of the cauda equina (14.6% versus 100%), thickening and echogenicity of the filum terminale (2.4% versus 100%), and the presence of a normal subarachnoid space (18.3% versus 100%) were significantly more difficult to detect in group B than in group A (all P < .001).

CONCLUSIONS

For an accurate evaluation, which can reduce unnecessary confusion and costs, spinal US can be delayed until neonates grow beyond 31 days, with a corrected age of older than 42.5 weeks and body weight of greater than 4.6 kg.

Utility of ureteric jet: A simple yet useful tool for the evaluation of complex urogenital anomaly

In infants and young children with suspicion of genitourinary tract anomalies, ultrasonography (USG) is usually the first imaging modality. Advantages of USG are well described. In the evaluation of complex congenital urogenital anomalies, ultrasound examination needs to be tailored according to the clinical suspicion and to yield maximum information. Primary megaureter is a congenital anomaly, which is associated with dilatation of ureter above an adynamic segment at the vesicoureteric junction (VUJ). Two different types are described in the literature: refluxing and obstructive. Absence of ureteric jet on USG in conjunction with vesicoureteric reflux (VUR) on voiding cystourethrogram (VCUG) prompts to the diagnosis of refluxing type of obstructed megaureter. Here we describe a case of duplex moiety with refluxing type of obstructed megaureter, where gray-scale USG and real-time color Doppler evaluation of the ureteric jet established the diagnosis. The aperistaltic segment of lower ureter near the VUJ with an absence of ureteric jet for the same moiety suggested the possibility of an obstructed megaureter. VUR was demonstrated on VCUG; thus, pointing toward a diagnosis of obstructed refluxing megaureter.

A Pediatrician's Take on a Few Common Infant Urologic and Gynecologic Issues

Urologic and gynecologic issues are common in a pediatric primary care office. This article focuses on the evaluation and management of a few common diagnoses in infants and young children: fetal hydronephrosis, labial adhesions, physiologic phimosis, and hydrocele. This article can help pediatricians decide when these common issues can be managed in the primary care office and when they need subspecialty guidance. [Pediatr Ann. 2017;46(11):e397-e399.].

Renal development in the fetus and premature infant

Congenital abnormalities of the kidney and urinary tract (CAKUT) are one of the leading congenital defects to be identified on prenatal ultrasound. CAKUT represent a broad spectrum of abnormalities, from transient hydronephrosis to severe bilateral renal agenesis. CAKUT are a major contributor to chronic and end stage kidney disease (CKD/ESKD) in children. Prenatal imaging is useful to identify CAKUT, but will not detect all defects. Both genetic abnormalities and the fetal environment contribute to CAKUT. Monogenic gene mutations identified in human CAKUT have advanced our understanding of molecular mechanisms of renal development. Low nephron number and solitary kidneys are associated with increased risk of adult onset CKD and ESKD. Premature and low birth weight infants represent a high risk population for low nephron number. Additional research is needed to identify biomarkers and appropriate follow-up of premature and low birth weight infants into adulthood.

Parenchyma-to-hydronephrosis Area Ratio Is a Promising Outcome Measure to Quantify Upper Tract Changes in Infants With High-grade Prenatal Hydronephrosis

OBJECTIVE

To explore the value of renal parenchyma-to-hydronephrosis area ratio (PHAR) in detecting trends of hydronephrosis (HN) improvement or worsening and response to surgical intervention.

METHODS

Initial and follow-up sagittal renal ultrasound images of patients entered into a prenatal HN database from 2008 to 2016, with baseline Society for Fetal Urology (SFU) grades III and IV HN and without vesicoureteral reflux, were evaluated using National Institutes of Health-sponsored image-processing software. Renal parenchymal area, hydronephrosis area (HA), PHAR, anteroposterior diameter (APd), and SFU grade were captured at baseline and most recent visit. Data were analyzed based on the need for surgical intervention to address obstruction.

RESULTS

Out of 193 infants (159 boys; 135 left side), 58 (30%) underwent surgery. Patients managed surgically compared with those managed nonsurgically had worse baseline HN severity markers: SFU grade (3.6 ± 0.5 vs 3.1 ± 0.4; P <.001), urinary tract dilation classification (2.7 ± 0.5 vs 2.2 ± 0.4; P <.001), APd (20.3 ± 10.1 vs 12.8 ± 8.0; P <.001), HA (10.0 ± 6.6 vs 4.7 ± 2.8; P <.001), and PHAR (1.3 ± 1.0 vs 3.0 ± 2.9; P <.001); but both patient groups had similar renal parenchymal area (9.4 ± 3.5 vs 9.7 ± 2.8; P = .5). At last follow-up, the following discrepancies persisted: SFU grade (2.3 ± 1.0 vs 1.7 ± 1.0; P <.001), urinary tract dilation classification (1.5 ± 0.7 vs 1.0 ± 0.7; P <.001), APd (11.7 ± 8.0 vs 7.7 ± 5.7; P <.001), and HA (6.4 ± 5.1 vs 3.6 ± 2.7; P <.001); however, PHAR was equalized for both groups (7.2 ± 14.0 vs 7.1 ± 6.1; P = .9).

CONCLUSION

By concurrently considering changes in renal parenchyma and degree of HN, we found that PHAR appears to be a promising parameter that reflects similarities between patients managed surgically and those managed nonsurgically, despite initial discrepancies. Our data suggest that this variable may provide reassurance and a more objective assessment of improvement after surgery compared with other traditional ultrasound outcome measures.

Maternal Urinary Carbohydrate Antigen 19-9 as a Novel Biomarker for Evaluating Fetal Hydronephrosis: A Pilot Study

OBJECTIVE

To evaluate maternal urinary CA19-9 as a potential marker to diagnose severe antenatal hydronephrosis (ANH) during pregnancy and to compare the values with those in normal pregnancies as controls.

PATIENTS AND METHODS

A total of 20 women in their third pregnancy trimester were enrolled. An anteroposterior pelvic diameter (APD) of ≥15 was considered as severe ANH. Case group consisted of 10 women with a diagnosis of severe ANH. Ten women with similar age, gestational age, fetal sex, normal ultrasonography, and no history of any congenital anomalies were chosen as controls. Urine samples were collected and maternal urinary CA19-9 was measured. The levels in case and control groups were compared using Mann-Whitney U test.

RESULTS

Each group consisted of nine mothers with male fetuses and one with female fetus. The APD in the ANH group ranged from 17 to 40 mm. Five of 10 children in the ANH group also had contralateral APD of ≥4 mm (bilateral ANH). The mean age and gestational age of pregnant women in the two groups were comparable. The mean maternal CA19-9 was significantly higher in the ANH group compared with the controls (mean: 134.5 U/mL vs 22.2 U/mL, P < .001).

CONCLUSION

To our best knowledge, this is the first time that maternal urinary CA19-9 has been used as a marker for ANH. Based on these pilot data, CA19-9 levels are significantly higher in the urine of pregnant women carrying fetuses with severe ANH, and it may have the potential to serve as a noninvasive and useful biomarker to diagnose ANH.