Neonatal renomegaly

Mild hydronephrosis in newborns and infants: can ultrasound predict the presence of vesicoureteral reflux

The objective of our study was to determine the significance of mild hydronephrosis in newborns and infants as an indicator of vesicoureteral reflux (VUR). The voiding cystourethrography (VCUG) of 573 patients aged 0-18 months with mild, sonographically detected hydronephrosis were reviewed for VUR. Patients with secondary reflux or anomalies making an exact reflux grading impossible were excluded. Normal kidneys, contralateral to hydronephrotic ones, were included. Each kidney was considered separately, forming a total of 1,146 renal units. Mild hydronephrosis was defined as an anteroposterior diameter of the renal pelvis of 0.5-1.5 cm without caliectasis. The International Grading System was used to grade VUR. Seven hundred and thirty-six kidneys had mild hydronephrosis. VUR occurred in 189 out of 736 (25.7%) of these kidneys, and in 108 out of 410 (26.3%) non-distended kidneys, contralateral to hydronephrotic ones (p=0.806). No statistical differences in the frequency of VUR and dilatation were found between the subgroups of patients with and without infection, except for a higher grade of reflux in the group with infection. The frequency of VUR in mildly dilated kidneys was not significantly different from that in non-distended ones. There was a poor correlation between VUR and mild hydronephrosis. The latter should not be considered in itself an indication for VCUG in asymptomatic neonates and infants.

Postnatal management of antenatally diagnosed ureteropelvic junction obstruction

OBJECTIVE

The management of antenatally diagnosed ureteropelvic junction obstruction (PUJO) is controversial. Here, we present our experience over a period of 13 years and discuss our management protocol.

MATERIALS AND METHODS

We reviewed the files of 234 patients with antenatally diagnosed congenital hydronephrosis due to PUJO. Management was tailored to each patient, based on a combination of diethylenetetraminepentacetic acid renogram outcome, pelvic diameter, as well as the patient's symptoms.

RESULTS

Pyeloplasty was carried out early in 52 kidneys. Of the total, 182 patients were managed expectantly. Out of these, 45 underwent delayed pyeloplasty. The remaining 137 patients (189 units) were managed non-operatively. In patients who underwent early pyeloplasty, the mean split differential renal function was 37% before and 40.05% after surgery. In those with delayed intervention, the mean renal function was 37.8% before and 42.2% after surgery. In patients who did not have surgery, the mean differential renal function was 45.7% initially and 48.2% at the last accepted follow up. The overall operative success rate was 97.9%.

CONCLUSION

We believe that pyeloplasty is the proper treatment for babies with congenital PUJO and <40% split differential function and/or pelvic diameter >35 mm at the initial visit. In other patients a period of observation is warranted, and pyeloplasty should be carried out only if their kidney function deteriorates or the renogram curve does not show improvement. With the excellent results of pyeloplasty we believe that a safer approach is to operate on more kidneys rather than risk of losing valuable kidney function.

Neonatal pyonephrosis--a case report

Pyonephrosis is uncommon in adults as well as children and rarely reported in neonates. Candidial pyonephrosis in a neonate has been first reported in 1988 which was associated with iatrogenic perirenal collection [Cohen, HL, Haller, JO. J ultrasound Med 1988; 7(11): 647]. This is the second reported case of neonatal pyonephrosis and the first due to Staphylococcus aureus.

[Role of scintigraphic tests in upper urinary tract dilatation in children]

The diuresis renography has an important place in the management of upper urinary tract dilatation in children. This non-aggressive and low irradiant exploration is very helpful to determine if hydronephrosis is obstructive or not and to evaluate the renal function impairment. The protocol of exam must be particularly rigorous and interpretation should take into account physiopathological factors that influence provocated diuresis. A well patient hydration and if necessary a bladder catheter are required. The MAG-3 is the radiopharmaceutical of choice especially in newborn and infants. The furosemide administration at 20 minutes after radiotracer injection is the most commonly used protocol and is generally sufficient to classify the urinary dilatation. Equivocal cases and symptomatic forms can benefit from a modified protocol in which furosemide is administered 15 minutes before radiotracer injection (F-15). False positive tests may result from a marked dilatation or renal function reduction. The place of diuresis renography in management of neonatal hydronephrosis is controversial, particularly because of the dynamic and evolving nature of this pathology.

Neonatal management. Role for early intervention

Although performing pyeloplasty on an infant with a relatively healthy kidney prior to the onset of renal damage is not as well-accepted as "aggressive observation," the authors argue that early intervention is the more "conservative" or safe method of treatment for infants with ureteropelvic junction (UPJ) obstruction. Using experimental and clinical data, the authors demonstrate that prolonged partial UPJ obstruction in the developing kidney causes significant renal morbidity with time.

Clinical relevance and implications of antenatal hydronephrosis

Detailed antenatal sonography was performed on 18766 pregnant women between 1990 and 1994. Antenatal hydronephrosis, defined as an antero-posterior diameter of the renal pelvis (APPD) greater than 5 mm, was detected in 100 cases (0.59%). Sixty four infants had postnatal hydronephrosis at one and/or six weeks after delivery; 21 of these had urological anomalies. Twelve infants had vesico-ureteric reflux. In all refluxing units the APPD of the renal pelvis was less than 10 mm. Three patients had obstruction at the pelviureteric junction (PUJ); all required surgery. Vesico-ureteric reflux is emerging as the most common urological finding in infants with antenatal hydronephrosis and is likely to be missed if kidneys with APPD of less than 10 mm are not further investigated. In contrast, pelvi-ureteric junction obstruction may be overdiagnosed, based only on drainage patterns of dynamic renogram studies.

Correlation of ultrasound and renal scintigraphy in children with unilateral hydronephrosis in primary workup

Ultrasound accurately detects hydronephrosis in infants and children, while nuclear medicine techniques quantify relative renal function in addition to characterizing the urodynamic relevance of hydronephrosis. This prospective study was undertaken to examine the relationship between ultrasound morphological findings and relative renal function, quantified with dynamic 99mtechnetium mercaptotriacetylglycine imaging, in the initial diagnostic workup of children with unilateral hydronephrosis. The ultrasound grade of hydronephrosis and relative renal function ipsilateral to the hydronephrosis were inversely related, indicating that with more severe hydronephrosis ultrasound fails to estimate the potential reduction of relative kidney function. Because renal function is not necessarily affected by hydronephrosis, renal scintigraphy is indicated to assess the functional status of hydronephrotic kidneys.

Managing apparent ureteropelvic junction obstruction in the newborn

A total of 97 newborns with apparent ureteropelvic junction obstruction was evaluated from mid 1984 to 1989. Evaluation and management are described. Of these patients 39 with an affected kidney showing good initial differential function (greater than 35%) by diethylenetriaminepentaacetic acid scan and 2 showing diminished function (less than 35%) were followed nonoperatively. Six patients (15%) eventually required pyeloplasty for diminishing function (4), urinary tract infections (1) or symptoms of colic (1). The 4 patients with diminishing function improved after pyeloplasty to at least the initial level. A total of 12 patients with good initial function (greater than 35%) of the affected kidney underwent early pyeloplasty (within 6 weeks of diagnosis). They were compared to the similar group of patients managed nonoperatively and followed by sequential renal scans. Eventual changes in percentage differential function in the nonoperative and early surgery groups were +2.8% and +4.1%, respectively. Changes in extraction factor were +0.8% (nonoperative group) and +0.9% (surgery group). No statistically significant difference was found. In the kidney with apparent ureteropelvic junction obstruction and good function, an initial nonoperative approach with sequential renal scan followup and pyeloplasty as needed appears to be reasonable and has resulted in no permanent loss of function.

Grading nephroureteral dilatation detected in the first year of life: correlation with obstruction

To understand better the significance of pediatric idiopathic nephroureteral dilatation the renal ultrasound images of patients less than 1 year old with hydronephrosis or hydroureteronephrosis were graded and compared to the radiological diagnosis of obstruction as determined by diuresis renography and/or urography. The study included 73 boys and 30 girls with hydronephrosis (76 patients) or hydroureteronephrosis (27). For hydronephrosis obstruction was diagnosed in 56 children (74%) and involved 61 of 97 kidneys (63%). For obstructed kidneys the mean grade of hydronephrosis (3.4 +/- 0.7 standard deviation) was statistically different from that of nonobstructed kidneys (1.6 +/- 0.8 standard deviation) (p less than 0.05). When the value to predict obstruction was set at grade 3 hydronephrosis or greater there was an 88% sensitivity and 95% specificity. For hydroureteronephrosis obstruction was diagnosed in 15 of 27 children (56%) and involved 17 of 34 kidneys (50%). The degree of dilatation was weighted as a score to assess the grades of hydronephrosis and ureteral dilatation, namely hydroureteronephrosis score equals grade of hydronephrosis plus grade of ureteral dilatation. In obstructed megaureters the mean hydroureteronephrosis score (5.8 +/- 1.0) was statistically different from that for nonobstructed megaureters (mean hydroureteronephrosis score 2.7 +/- 1.9) (p less than 0.001). When the value to predict obstruction was set at hydroureteronephrosis score of 5 or greater there was a 94% sensitivity and 80% specificity. Although ultrasound examination alone cannot be used to diagnose urinary obstruction, the radiological diagnosis of obstruction is linked with the grade of hydronephrosis or score of hydroureteronephrosis.

Transitional hydronephrosis of the newborn and infant

Between 1986 and 1988, 187 hydronephrotic renal units were discovered antenatally in 134 subjects and confirmed in the neonatal period. Of these cases 119 (64%) were due to anomalies of the ureteropelvic junction. The remainder (36%) were due to various congenital uropathic conditions. Investigation consisted of renal ultrasonography, voiding cystourethrography and diuretic renography with 99mtechnetium-diethylenetriaminepentaacetic acid augmented with furosemide. Of the 119 renal units 36 (30%) underwent pyeloplasty, while 42 (35.7%) were considered normal without obstruction or dilatation. In 41 units (34.3%) diuretic renography showed partial obstruction or dilatation without obstruction that washed out readily with furosemide. Serial renal ultrasonography and renography were performed in these patients. A 12-month followup showed improvement or stabilization in 80% of the renal units and deterioration to significant obstruction in 20%. In attempting to identify the renal units that were most at risk for deterioration, it was realized that the initial ultrasound had a predictive role. None of the mildly hydronephrotic units deteriorated, whereas 14% of the moderately hydronephrotic and 32% of the markedly hydronephrotic units showed further deterioration. However, whether diuretic renography initially demonstrated partial obstruction or dilatation without obstruction, the ultimate outcome could not be predicted. Based on this experience an algorithm is proposed for the evaluation and management of antenatally detected hydronephrosis with currently available imaging techniques.

Changing concepts in management of primary obstructive megaureter

The management of neonatal urinary tract dilatations represents one of the most challenging dilemmas in pediatric urology today. We have been confronted with 44 renal units in 35 neonates diagnosed as having primary obstructive megaureter during the last 6 years. Of these units 23 in 17 infants were diagnosed antenatally and 20 (87 per cent) have been managed without surgical intervention. Notably, 16 renal units were graded as moderate to severe megaureters by an excretory urogram. The decision to manage conservatively was based on the initial extraction of the 99mdiethylenetriaminepentaacetic acid renal scan (the extraction factor). This estimate of absolute renal function has been used to differentiate dilatations with obstructive implications for the renal parenchyma from those without. Significantly, expectant treatment has resulted in improvement of dilatation on sequential excretory urograms in 15 megaureters and none has shown a deterioration of function by renal scan. Similar diagnostic criterion also has resulted in conservative management for 12 of 21 additional neonatal megaureters seen during this period with symptoms or they were discovered serendipitously. Only 2 of these 12 megaureters required surgical correction. The neonatal primary megaureter appears in many cases to represent a different entity than those that commonly presented before the advent of antenatal and perinatal diagnosis.

The fate of infant kidneys with fetal hydronephrosis but initially normal postnatal sonography

Antenatal hydronephrosis involving 49 renal units in 35 infants seen since 1984 was studied. Postnatal sonography performed in the first few days after birth confirmed upper tract dilatation in 39 kidneys (80 per cent) in 29 neonates and it was normal in 10 kidneys (20 per cent) in 6 neonates. Of the 6 neonates with a normal postnatal sonogram 5 underwent repeat renal sonography at an average of 2 months after birth, all showing moderate hydronephrosis (7 kidneys). Furosemide-enhanced diethylenetriaminepentaacetic acid renography was performed in 4 infants (5 kidneys) with ureteropelvic junction or megaureter obstruction, of whom 2 had persistent unilateral obstruction and underwent successful reconstructive surgery (1 pyeloplasty and 1 megaureter reimplantation). Two infants (3 kidneys) with nonobstructive dilatation are being followed while 1 infant with bilateral vesicoureteral reflux is being managed medically on long-term antimicrobial prophylaxis. Thus, 50 per cent of neonates with antenatal hydronephrosis and a normal postnatal sonogram performed during the first few days of life subsequently were found to have either significant obstruction (2 requiring surgery) or reflux. This study underscores the absolute necessity of followup sonography in all newborns with antenatal hydronephrosis that is not confirmed on the initial postnatal ultrasound.

Intermittent hydronephrosis: a diagnostic challenge

Intermittent hydronephrosis is a difficult condition to diagnose because of the mild degree of dilatation encountered in imaging studies. The condition nevertheless is disabling and attempts to reach a precise diagnosis include diuretic excretory urography, ultrasonography and renal scans. The delayed double-peak pattern seen on 99mtechnetium-diethylenetriaminepentaacetic acid diuretic renography shows how the ureteropelvic junction can become self-obstructing with forced diuresis. All patients who exhibited this sign eventually had frank obstruction and most exhibited an extrinsic component to the obstruction. The recognition of the double-peak pattern may become a useful adjunct in the early diagnosis of intermittent hydronephrosis.