Accuracy of renal-bladder ultrasonography as a screening method to suggest posterior urethral valves

Abdominal distension and lower extremity edema

Posterior urethral valves are a congenital malformation in males that results in the obstruction of urinary outflow from the proximal urethra. Presentation depends on severity of disease, with patients presenting antenatally with oligohydramnios and hydronephrosis, to postnatally with delayed or poor voiding, urinary tract infections, or renal anomalies on ultrasound. Our case illustrates an 11-day-old male who presented to the emergency department with poor feeding, vomiting, significant abdominal distension, and pitting edema of the lower extremities. The patient was found to have hypoglycemia, hyponatremia, hyperkalemia, and acute renal failure. Point of care ultrasound showed severe bilateral hydronephrosis with a significantly distended bladder that was compressing the inferior vena cava. Early recognition of the obstruction via ultrasound led to rapid decompression of the bladder using catheterization and immediate involvement of urology, nephrology, and neonatology consults in the pediatric emergency department.

Microtomographic analysis of lower urinary tract obstruction

Prenatal obstruction of the lower urinary tract may result in megacystis, with subsequent development of hydroureter, hydronephrosis, and renal damage. Oligo- or anhydramnios, pulmonary hypoplasia, and prune belly syndrome are lethal consequences. Causes and mechanisms responsible for obstruction remain unclear but might be clarified by anatomic study at autopsy. To this end, we employed 2 methods of tomographic imaging-optical projection tomography and contrast-enhanced microCT scanning-to elucidate the anatomy of the intact urinary bladder and urethra in 10 male fetuses with lower urinary tract obstruction. Images were compared with those from 9 age-matched controls. Three-dimensional images, rotated and sectioned digitally in multiple planes, permitted thorough examination while preserving specimens for later study. Both external and internal features of the bladder and urethra were demonstrated; small structures (ie, urethral crest, verumontanum, prostatic utricle, ejaculatory ducts) were seen in detail. Types of obstruction consisted of urethral atresia (n  =  5), severe urethral stenosis (n  =  2), urethral diaphragm (n  =  2), or physical kinking (n  =  1); classic (Young type I) posterior urethral valves were not encountered. Traditional light microscopy was then used to verify tomographic findings. The prostate gland was hypoplastic or absent in all cases; in 1, prostatic tissue was displaced inferior to the verumontanum. Findings support previous views that dissection may produce valve-like artifacts (eg, bisection of an obstructing diaphragm) and that deformation of an otherwise normal urethra may result in megacystis. The designation "posterior urethral valves" should not be used as a generic expression of urethral obstruction unless actual valves are demonstrated.

Voiding urosonography as first step in the diagnosis of vesicoureteral reflux in children: a clinical experience

BACKGROUND

Contrast-enhanced voiding urosonography (VUS) is becoming more widely used for the diagnosis of vesicoureteric reflux (VUR), but until now its use has only been accepted for first diagnosis in females and in the follow-up of children, including boys, who have already undergone voiding cystourethrography (VCUG).

OBJECTIVE

To describe our 6-year experience with VUS used as a first step in the diagnosis of VUR.

MATERIALS AND METHODS

A total of 610 children (334 boys, 276 girls; mean age 22 months), underwent VUS as the first step in the diagnosis of VUR. In selected children, VCUG was also performed.

RESULTS

VUR was detected in 199 of 610 VUS examinations, and 265 refluxing kidney-ureter units were found. Children with VUR underwent antibiotic prophylaxis or surgery. Children without VUR underwent clinical follow-up. Just 60 children underwent VCUG. The criteria for VCUG were: high-grade VUR after consultation with a urologist, onset of urinary tract infection while receiving prophylaxis, nondiagnostic VUS, and other malformations with or without clinical signs.

CONCLUSION

Our experience suggests that we can use VUS as the first step in the diagnosis of VUR in children, boys and girls, with a significant reduction in radiation exposure.