A practical guide to urinary tract ultrasound in a child: Pearls and pitfalls

Assessment of urine metabolite biomarkers for the detection of S. haematobium infection in pre-school aged children in a rural community in Zimbabwe

BACKGROUND

Early diagnosis of urogenital schistosomiasis is key to its control and elimination. The current gold standard microscopic examination techniques lack sensitivity in detecting light Schistosomiasis infections in pre-school aged children thus it is urgent to develop diagnostic tools that may be integrated into control programs. In this study, we evaluated the diagnostic performance of urine metabolite biomarkers using a chemical reagent strip in the detection of S. haematobium infection in pre-school aged children.

METHODS

A case-control study was conducted involving 82 pre-school aged children that were age and sex matched. Urine samples were collected for 3 consecutive days and were evaluated using urine filtration gold techniques as the gold standard method. The samples were simultaneously measured for metabolite biomarkers specifically haematuria, proteins, ketones, nitrites, glucose, bilirubin and urobilinogen using chemical reagent strips. Pearson correlation test was used to measure the relationship between S. haematobium infection and the urine metabolite biomarkers.

RESULTS

The diagnostic performance of urine biomarkers were correlated with the microscopic examination urine filtration technique. Haematuria (r = 0.592, p = 0.0001) and proteinuria (r = 0.448, p = 0.0001) were correlated to S. haematobium infection. Negative correlations with p > 0.05 were recorded for ketones and urobilinogen. Highest sensitivity was 65.9 % (CI, 49.4 - 79.9) for haematuria whilst protein (albumin) biomarker had a lower specificity value of 43.9 % (28.5 - 60.3). Inversely, highest sensitivity was 87.8 % (73.8 - 95.9) for proteinuria whilst haematuria had a lower sensitivity value of 82.9 % (67.9 - 92.8). The positive predictive values ranged from 57.7 % (41.6 - 72.2) to 79.4 % (65.5 - 88.7) whereas negative predictive values ranged from 70.8 % (60.8 - 79.2) to 52.0 % (48.7 - 55.3). With respect to diagnostic efficiency, haematuria had a fair diagnostic performance with an area under the curve of 0.76 followed by proteinuria with proteinuria whilst the remaining metabolites fail discriminating ability with an area under the curve of <0.5.

CONCLUSION

Although haematuria and protein biomarkers in urine are moderately sensitive and specific, they are important morbidity indicators of urogenital schistosomiasis in pre-school aged that may be utilised during screening in schistosomiasis control programs. We recommend comprehensive analysis of biomarkers using metabolomics techniques to identify novel urine biomarkers.

Primary non-refluxing megaureter: Natural history, follow-up and treatment

Primary non-refluxing megaureter (PMU) is a congenital dilation of the ureter which is not related to vesicoureteral reflux, duplicated collecting systems, ureterocele, ectopic ureter, or posterior urethral valves and accounts for 5 to 10% of all prenatal hydronephrosis (HN) cases. The etiology is a dysfunction or stenosis of the distal ureter. Most often PMU remains asymptomatic with spontaneous resolution allowing for non-operative management. Nevertheless, in selective cases such as the development of febrile urinary tract infections, worsening of the ureteral dilatation, or reduction in relative renal function, surgery should be considered.

CONCLUSION

Ureteral replantation with excision of the dysfunctional ureteral segment and often ureteral tapering is the gold-standard procedure for PMU, although endoscopic treatment has been shown to have a fair success rate in many studies. In this review, we discuss the natural history, follow-up, and treatment of PMU.

WHAT IS KNOWN

• PMU is the result of an atonic or stenotic segment of the distal ureter, resulting in congenital dilation of the ureter, and is frequently diagnosed on routine antenatal ultrasound.

WHAT IS NEW

• Most often, PMU remains asymptomatic and clinically stable, allowing for non-operative management. • Nevertheless, since symptoms can appear even after years of observation, long-term ultrasound follow-up is recommended, even up to young adulthood, if hydroureteronephrosis persists. • Ureteral replantation is the gold standard in case surgery is needed. In selected cases, however, HPBD could be a reasonable alternative.

Increased incidence of renal and urinary tract anomalies among individuals with fetal alcohol spectrum disorders (FASD)

BACKGROUND

Fetal alcohol spectrum disorders (FASD) in a spectrum of neurodevelopmental conditions resulting from prenatal alcohol exposure (PAE). Animal models have confirmed the toxic effects of PAE on the kidneys and urinary tract, yet the evidence from human studies is contradictory. The purpose of this study was to establish the incidence of renal and urinary tract anomalies (RUTA), impaired kidney function, and hypertension among patients with FASD.

METHODS

Children from the FASD Diagnostic Center with FASD diagnosis (FAS, pFAS, or ARND) were offered participation in the study. The control group consisted of patients from the Gastroenterology Department of the same hospital. The patients underwent renal and urinary tract ultrasound examination. The serum creatinine level was also evaluated and the blood pressure was taken twice. Polish OLAF charts were used to determine the percentiles of blood pressure.

RESULTS

The incidence of kidney and urinary tract defects in the study group was significantly higher than in the control group (OR: 2.64 [1.60-4.34]). The kidney size among FASD patients was significantly lower (73 mm [60-83] vs. 83 mm [70-96]; p < .001) when compared to the control group. No differences were observed in the estimated glomerular filtration rate. In the study group, significantly lower systolic blood, diastolic blood pressure, percentile of systolic pressure, and diastolic pressure were observed.

CONCLUSIONS

RUTA occurred more frequently among patients with FASD compared to the control group, and decreased kidney size was also demonstrated among patients with FASD. However, impaired kidney function and the risk of hypertension were not observed.

Application of the postnatal urinary tract dilation classification system to predict the need for surgical intervention among neonates and young infants

PURPOSE

The aim of this study was to validate the postnatal urinary tract dilation (UTD) classification system by correlating it with the need for surgical intervention.

METHODS

Young infants who underwent ultrasound (US) examinations for prenatal hydronephrosis were retrospectively identified. The kidney units (KUs; right, left, or bilateral) were graded from UTD P0 (very low risk) to P3 (high risk) based on seven US criteria from the UTD system. Surgery-free survival curves were constructed using the Kaplan-Meier method. Univariable and multivariable Cox proportional-hazards regression analysis clustered by patients was performed. Interobserver agreement was analyzed using the weighted kappa coefficient.

RESULTS

In total, 504 KUs from 336 patients (mean age, 18.3±15.9 days; range, 1 to 94 days; males, n=276) were included, with a median follow-up of 24.2 months. Fifty-eight KUs underwent surgical intervention. Significant differences were observed among the Kaplan-Meier curves stratified into UTD groups (P<0.001). The presence of anterior-posterior renal pelvic diameter ≥15 mm (hazard ratio [HR], 8.602; 95% confidence interval [CI], 1.558 to 43.065), peripheral calyceal dilation (HR, 8.190; 95% CI, 1.558 to 43.065), ureteral dilation (HR, 2.619; 95% CI, 1.274 to 5.380), parenchymal thickness abnormality (HR, 3.371; 95% CI, 1.574 to 7.223), bladder abnormality (HR, 12.209; 95% CI, 3.616 to 41.225) were significantly associated with the occurrence of surgery. The interobserver agreement was moderate to almost perfect agreement for US features (κ=0.564-0.898) and substantial for final UTD grades (κ=0.716).

CONCLUSION

The UTD classification system is reliable and appropriately stratifies the risk of surgical intervention.

Zinner syndrome in children: clinical presentation, imaging findings, diagnosis, and outcome

BACKGROUND

Zinner syndrome (ZS), the association of congenital seminal vesicle cyst (SVC) and ipsilateral kidney anomalies, is rarely diagnosed in childhood. This study aimed to assess presentation, imaging findings, management, and outcome of pediatric ZS.

METHODS

Sixteen children with ZS were diagnosed and managed at our hospital from 2003 to 2021. We reviewed the medical records to collect data on initial symptoms, results of imaging studies, complications, operation, and follow-up.

RESULTS

Ultrasound was used in all 16 cases as initial diagnostic tool. Fourteen patients were asymptomatic at diagnosis: these were transferred from obstetricians or pediatricians for evaluation of the prenatally or postnatally detected ultrasonic kidney anomalies. SVCs were incidentally noted on ultrasonography. The other two cases initially presented with urinary tract infection (UTI). Kidney anomalies included multicystic dysplastic kidney in 3 and kidney agenesis in 13 patients. Eleven (68.7%) patients had ipsilateral ectopic ureters entering SVC. Four (36.4%) patients had a reflux from urethra into SVC (urethro-cystic reflux) on voiding cystourethrography. Ten (62.5%) patients remained asymptomatic over a mean of 58 months (range, 7-216 months), two patients developed lower urinary tract dysfunction, and five patients had UTIs. Two boys needed SVC removal, and SVC had disappeared in two patients after 2.5-4 years of follow-up.

CONCLUSIONS

Unilateral kidney hypodysplasia with ectopic ureter inserting into the ipsilateral SVC is a characteristic sign for diagnosis of ZS. In our case series, ZS was mainly asymptomatic. Urethro-cystic reflux was associated with UTIs in young infants. SVC removal was rarely required. A higher resolution version of the Graphical abstract is available as Supplementary information.

Prolonged Indwelling Urethral Catheterization as Minimally Invasive Approach for Definitive Treatment of Posterior Urethral Valves in Unstable Premature Babies

Premature newborns with posterior urethral valves (PUV) may present with medical conditions taking priority over definitive surgical care. We encountered three of such cases who underwent initial bladder decompression via transurethral catheterization and waited 2-3 weeks until they were fit enough for voiding cysto-urethrography to confirm PUV. An unexpected good urinary flow and negligible residual urine volume were documented during micturition, suggestive of valve disruption induced by insertion and prolonged duration of indwelling urethral catheter drainage. Cystoscopy documented non-obstructing remnant leaflets. Non-operative treatment may be considered as a viable alternative therapeutic option for PUV in tiny babies facing prolonged intensive care unit stay.

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.

Pediatric cystic diseases of the kidney

Pediatric renal cystic diseases include a variety of hereditary or non-hereditary conditions. Numerous classifications exist and new data are continuously published. Ultrasound is the primary technique for evaluating kidneys in children: conventional and high-resolution US allows a detailed visualization of renal parenchyma and of number, size and location of the cysts, hence representing the most important diagnostic imaging technique for the first diagnosis and follow-up of these young patients. The purpose of this pictorial essay is to review the spectrum of renal cystic lesions in children from simple, complex or malignant single cysts to the several poly/multicystic kidney diseases.