Contrast enhanced Voiding Urosonography (ceVUS) will be performed with the intravesical administration of 0.1%-0.5% OPTISON / normal saline solution. The exact OPTISON dose (ml) that will be adjusted according to the age-related bladder filling capacity with a dose (ml) range from 0.3 mL in newborns to 3 mL in 18 year-old children. Voiding Cystourethrography (VCUG) exam will be subsequently performed using the same bladder catheter with intravesical administration of the x-ray contrast agent.

Contrast enhanced Voiding Urosonography (ceVUS) with intravesical administration of OPTISON for vesicoureteral reflux detection and urethral imaging in children. Voiding Cystourethrography (VCUG) examination will be subsequently performed as part of the standard care.

1. Presence or absence of vesicoureteral reflux identified by ceVUS and VCUG in each pelvic-ureter-unit (PUU) of each participant. PUU is an anatomic term that is used to describe the part of the urinary tract consisting of the renal calyces, pelvis and ureter.
2. Grading the severity of reflux detected by ceVUS and VCUG. Grade 0: absence of reflux. If reflux is present, a 5 grade scale (grades I-V) is used to evaluate its severity. Grade I: reflux in the ureter, grade II: reflux up to the renal pelvis, grade III: reflux up to the renal pelvis with mild dilation of the ureter and pelvicalyceal system, grade IV reflux up to the renal pelvis with moderate dilation but preserved papillary impressions, grade V: reflux up to the renal pelvis with severe dilation and loss of papillary impressions. Higher grades of reflux are associated with increased risk of urinary tract infection.
3. Imaging of the urethra during voiding (urethra visualized or not) and urethra pathology detection.

The overall safety and tolerability of ceVUS with OPTISON was assessed before, during and immediately after each ceVUS and VCUG examinations, and in follow-up telephone interviews. Assessments included:

1. evaluation of body systems for signs of generalized hypersensitivity, allergic or anaphylactoid reactions
2. monitoring of heart rate and pulse oxygen saturation
3. telephone questionnaire-based interview of parents/guardians and children 48 hours after the examinations for delayed adverse events.

The severity of any possible adverse event was classified as mild, moderate or serious and the onset of symptoms was categorized as acute, subacute or delayed according to the World Health Organization (WHO) classifications. In addition, the adverse event was classified as anticipated if it was expected given the study related procedures or unanticipated if the subject was exposed to greater risk than previously known or recognized.

The diagnostic accuracy of ceVUS will be assessed by evaluation of the true positive, true negative, false positive and false negative cases of reflux and urethral imaging findings detected by ceVUS and VCUG examinations.

OPTISON will be resuspended just before the performance of ceVUS examination, and 01%-0.5% OPTISON solution will be used for intravesical administration. The exact OPTISON dose (ml) will be adjusted according to the age-related bladder filling capacity with a maximum dose (ml) range from 0.3 mL in newborns to 3 mL in 18 year-old children. VCUG exam will be performed as part of the standard care using the same bladder catheter with intravesical administration of the x-ray contrast agent.

1. Presence or absence of vesicoureteral reflux identified by ceVUS and VCUG in each pelvic-ureter-unit (PUU) of each participant. PUU is an anatomic term that is used to describe the part of the urinary tract consisting of the renal calyces, pelvis and ureter.
2. Grading the severity of reflux detected by ceVUS and VCUG. Grade 0: absence of reflux. If reflux is present, a 5 grade scale (grades I-V) is used to evaluate its severity. Grade I: reflux in the ureter, grade II: reflux up to the renal pelvis, grade III: reflux up to the renal pelvis with mild dilation of the ureter and pelvicalyceal system, grade IV reflux up to the renal pelvis with moderate dilation but preserved papillary impressions, grade V: reflux up to the renal pelvis with severe dilation and loss of papillary impressions. Higher grades of reflux are associated with increased risk of urinary tract infection.
3. Imaging of the urethra during voiding (urethra visualized or not) and urethra pathology detection.

In total, 59 kidneys with 62 pelvic-ureteric units (PUUs) in 30 children were analyzed.

OPTISON will be resuspended just before the performance of ceVUS examination, and 0.1%-0.5% of the bladder filling volume OPTISON / normal saline solution will be used for intravesical administration. The exact OPTISON dose (ml) will be adjusted according to the age-related bladder filling capacity with the maximum OPTISON dose (ml) range from 0.3 mL in newborns to 3 mL in 18 year-old children.

VCUG exam will be performed using the same bladder catheter with intravesical administration of the x-ray contrast agent.

The dysuria was an anticipated adverse event and it was categorized as mild in severity, subacute in onset and self-limited in course. No medical consultation, no medication or other intervention was required or performed.