Nonoperative management of unilateral neonatal hydronephrosis

Management of neonatal hydronephrosis

Management of neonatal hydronephrosis is a clinical challenge. The natural history of hydronephrosis has shown that most resolve spontaneously; however, there are a significant number that do not. Although hydronephrosis does not always mean obstruction, it becomes the clinician's role to determine when obstruction will eventually lead to renal damage. Work-up of hydronephrosis diagnosed prenatally starts with a postnatal ultrasound. Using the Society of Fetal Urology (SFU) grading of hydronephrosis based on ultrasonography, a management and treatment algorithm can be constructed. Other studies include a voiding cystourethrogram to evaluate for vesicoureteral reflux or in severe cases of bilateral hydronephrosis to evaluate for posterior urethral valves. Diuretic renography is useful in many cases to evaluate the degree of obstruction and determine differential renal function. The goal is to select the patients who would benefit from early surgical intervention. To achieve that goal, aggressive observation is often required.

Prenatally detected primary megaureter: a role for extended followup

PURPOSE

A high rate of spontaneous resolution of or decrease in urinary tract dilatation is expected for most cases of primary megaureter (PM). We analyzed our results with extended long-term nonsurgical treatment in a group of children diagnosed with prenatally detected PM. We also sought to determine the long-term safety of this approach and the clinical significance of residual hydroureteronephrosis (HUN) when complete resolution does not occur.

MATERIALS AND METHODS

We reviewed our experience with 40 infants with prenatally detected hydronephrosis diagnosed as PM who were initially treated nonoperatively between 1986 and 1999. Patients were followed with ultrasonography, nuclear renography and, in some instances, excretory urogram until stable improvement or complete resolution of HUN was noted. Records for patients who specifically returned for long-term followup history and radiological imaging were also reviewed.

RESULTS

Of 40 patients with 57 megaureters (17 with bilateral PMs) who were followed 4 infants (10%) with severe HUN were diagnosed with diminished renal function by nuclear renography and underwent surgical repair. A total of 27 infants (67.5%, 40 megaureters) with PM who were followed without surgical intervention returned for followup examination and imaging for a minimum of 24 months after initial diagnosis, for a mean of 6.8 years (range 24 to 210 months). Ultrasonography in these patients revealed complete resolution (Society for Fetal Urology grade 1 or less hydronephrosis) in 21 megaureters (52.5%) at a mean of 2.9 years and improved or stable HUN in 19 megaureters (47.5%). Antibiotic prophylaxis was administered to 12 patients beyond the first month of life and discontinued at a mean age of 19.9 months. A subgroup of 10 patients (16 megaureters) from this cohort returned for extended followup imaging at a mean of 13.4 years (range 84 to 210 months) following initial diagnosis. Four patients with documented resolution of HUN had no recurrence during long-term followup. One male with bilateral PMs diagnosed at birth that had been stable but were not resolved at 8-year followup suffered significant worsening in the degree of HUN, diminished renal function on 1 side and a renal stone on the contralateral renal unit at 14-year followup, despite remaining asymptomatic.

CONCLUSIONS

Long-term followup of children with prenatally diagnosed PM with mild to moderate hydronephrosis confirms a high incidence of resolution and improvement. As we have documented 1 case of worsening HUN at 14-year followup, we believe that ultrasonography should be periodically continued until the child reaches adulthood, at least in instances where complete resolution of HUN is not documented.

[Neonatal pelvic ectasia: long-term outcome and association with ureterovesical anomalies]

OBJECTIVE

To analyze the outcome of neonatal pelvic ectasia (PE) and the association between this entity and vesicoureteral reflux and/or other urinary tract abnormalities.

PATIENTS AND METHODS

We performed a retrospective study of 255 children (205 boys, 50 girls) with an ultrasonographic diagnosis of PE in the first month of life. The initial ultrasonographic examination was indicated by urinary tract infection in 30 neonates, abnormalities in the prenatal ultrasonographic examination in 150 and by other reasons in 75. Pelvic ectasia was classified in four stages according to anteroposterior pelvic diameter: I < 1 cm, II 1-1.5 cm, III 1.6-2 cm, and IV > 2 cm.

RESULTS

Pelvic ectasia was bilateral in 153 children (60 %) and unilateral in 102 (left side in 81.4 % and right side in 18.6 %). Stage I was found in 75.49 %, stage II in 20.34 %, stage III in 3.9 % and stage IV in 0.24 %. The mean follow-up was 32.6 +/- 25.2 months. At the end of the first year, the results of renal ultrasound were normal in 70.2 % of left-sided PE and in 55.9 % of right-sided PE, but 46 patients (18 %) showed worsening of PE between the first and second ultrasound scans. Voiding cystourethrography was performed in 79.6 % of the children and some abnormalities were found in 50 (24.6 %): urethral dilatations in two patients and vesicoureteral reflux in 48. No correlation was found between vesicoureteral reflux and the degree of ectasia (74 % had an anteroposterior diameter of < or = 1 cm). Urinary tract infection was present in 24.3 % of the children and 13 required surgery (eight pyeloplasties, four urethral reimplantations and two resections of type III urethral valves).

CONCLUSIONS

Neonatal PE was more prevalent in boys (4:1) and was more frequently located on the left side in both sexes. Associated vesicourethral reflux was found in 23.64 % with no correlation between the degree of dilation and the presence or degree of reflux. Consequently, cystourethrography should be performed in any child with pelvic ectasia, regardless of stage, side or sex.

Congenital midureteral stricture in children diagnosed with antenatal hydronephrosis

OBJECTIVES

Antenatal hydronephrosis is the most common genitourinary pathologic finding during gestational ultrasonography. Congenital midureteral strictures are an unusual cause of prenatal hydronephrosis, with 13 total previously reported and only 1 diagnosed as a result of antenatal ultrasonography.

METHODS

We present 4 cases of midureteral strictures as the cause of antenatal hydronephrosis and review the published data on congenital midureteral obstruction.

RESULTS

All midureteral strictures in our series and in the published reports were treated surgically after varying periods of observation. Retrograde pyelography was diagnostic in all cases.

CONCLUSIONS

This atypical cause of antenatal hydronephrosis may provide additional insight into the controversy regarding preoperative retrograde pyelography before surgical intervention for ureteropelvic junction obstruction. Given the typical misdiagnosis of ureteropelvic junction obstruction in the setting of midureteral stricture disease, we believe that the threshold for retrograde pyelography should be very low.

PRENATALLY DIAGNOSED UNILATERAL RENAL PELVIC DILATATION: A DYNAMIC CONDITION ON ULTRASOUND AND DIURETIC RENOGRAPHY

PURPOSE

Imaging characteristics obtained from serial scintigraphic and ultrasonographic studies in children with the prenatal diagnosis of unilateral pelvic dilatation are presented.

MATERIALS AND METHODS

Serial ultrasonographic and scintigraphic findings in 101 children with unilateral pelvic dilatation collected during followup were reviewed. Changes in hydronephrotic kidney in terms of renal pelvis diameter, kidney size, differential renal function and drainage were noted. A total of 42 children underwent surgery at a mean age of 15.6 months (range 3.1 to 69.2, median 8.2), while 59 were treated nonsurgically.

RESULTS

Mean age at presentation was 5.6 months (range 0.8 to 36.4, median 3.5). Mean followup was 35.5 months (range 6.4 to 78.4, median 29.6). Differential renal function remained stable (46.4% vs 47.3%) but improved drainage (68.4% vs 81.2%) and decreased renal pelvis size (22.2 vs 18.3 mm) was noted in the 2 groups. With age drainage function improved, especially between the younger than 12-month and 12-month or older groups. The mean affected-to-unaffected kidney length ratio at presentation was significantly greater than the ratio at the final followup (paired t test p <0.05).

CONCLUSIONS

In this retrospective review drainage function was prolonged in infants. During followup drainage, dilatation and relative renal size improved in the surgery and nonsurgery groups. There was no change in renal function in either groups during followup. These data support the benign nature of prenatal unilateral hydronephrosis.

Upper urinary tract: when is obstruction obstruction?

PURPOSE OF REVIEW

Obstruction can either be defined as a condition that hampers optimal renal development, or, more conservatively, as a restriction to urinary outflow that, when left untreated, will cause progressive renal deterioration. Currently, management is mostly based on the latter definition, but still remains controversial. Relevant work published before 2002 is considered because of a lack of recent literature.

RECENT FINDINGS

Almost all reports comparing the primary conservative treatment of suspected obstruction versus early surgical intervention show comparable results, but there are different interpretations. The approach of 'watch and wait' for a unilateral hydronephrotic kidney with normal function is usually quite safe, with a very low risk of the permanent loss of renal function when accompanied by close monitoring, but it is certainly not without risk. At this time, the main underlying problems are that all currently applied diagnostic methods only detect effects secondary to obstruction, and the currently used definition of obstruction is based on a longitudinal observation period. The most relevant publication in the observation period was an in-depth report on a workshop in which the need for valid prospective markers for renal maldevelopment and 'significant' obstruction was expressed.

SUMMARY

The optimal management of infants with congenital hydronephrosis and suspected obstruction will remain controversial until new diagnostic methods are able to discriminate between 'harmful' and 'harmless' obstruction. Most experts currently advocate primary conservative management, with close follow-up and surgical intervention only if there are signs of reduced function of the obstructed kidney.

Changing concepts in urological management of the congenital anomalies of kidney and urinary tract, CAKUT

Recent advancement in ultrasonographic evaluation has prompted early detection and diagnosis of congenital anomalies in the kidney and urinary tract (CAKUT) in the asymptomatic phase. Consequently, early surgical intervention has become possible in the asymptomatic phase for the purpose of controlling manifestations early, thereby avoiding renal functional deterioration. However, some lesions detected by ultrasonography have been shown to often resolve or disappear without intervention. Thus, it has become more important to identify and understand the natural history of CAKUT. For the precise evaluation of the results of surgical intervention, one must understand the maturational process of renal function during infancy. Without considering this process, we cannot differentiate the renal significance of the surgical management from the natural course of CAKUT. Recent advancement in the field of radioisotopic studies has also made a major contribution to the more precise assessment of renal function. Recent progress in the understanding of the pathophysiology and the natural history of CAKUT has helped rationalize its treatment and management. Improvement in the surgical techniques and tools, together with improvements in pediatric anesthesiology, have made an appreciably positive impact on the outcome. Herein, we present the emerging concepts in the urological management of CAKUT, specifically, multicystic dysplastic kidney, vesicoureteral reflux, congenital hydronephrosis, ectopic ureters and ureteroceles.

The results of 15 years of consistent strategy in treating antenatally suspected pelvi-ureteric junction obstruction

OBJECTIVE

To determine how to select patients for surgery among those with antenatally detected pelvi-ureteric junction (PUJ) obstruction.

PATIENTS AND METHODS

The study comprised 100 consecutive children with antenatally detected suspected unilateral PUJ obstruction and a normal contralateral kidney. The correct diagnosis was made using postnatal ultrasonography, intravenous urography and renal scintigraphy, the last also being used for the follow-up.

RESULTS

Four patients had poor function in the hydronephrotic kidney, treated in three by nephrectomy; 61 had normal function in the hydronephrotic kidney, with 49 followed for 1-10 years with no change in kidney function and no symptoms. Twelve patients in this group had later surgery (at 0.7-8 years old) because of pyelonephritis (four), pain and/or renal functional impairment (eight, three of whom had normal function afterward). Thirty-five patients had moderately impaired function of the hydronephrotic kidney; 29 had primary surgery at a median age of 4 months. The median hydronephrotic renal function increased from 32% before to 42% after surgery, with 15 kidneys having normal function. In one other patient the kidney was lost before surgery. Five other patients were initially treated conservatively and the hydronephrotic renal function increased from 32% to 35% at the 1-year follow-up, significantly less than in the surgical group. The overall operative complication rate was 4%.

CONCLUSIONS

With our management programme more than half the patients can avoid surgery in childhood. Although the follow-up was intense there was moderate and irreversible functional kidney deterioration in 5%. In contrast, after successful reconstructive surgery, only a few follow-up procedures causing possible discomfort to the child are needed in most. The risk of surgical complications cannot be neglected. The present results are useful for advising parents deciding whether their antenatally detected hydronephrotic child should undergo surgery or not.

Pyeloplasty in infancy

OBJECTIVE

The advent of routine maternal ultrasound has increased the number of neonates diagnosed to have ureteropelvic junction obstruction. Though the debate concerning its ideal management continues, recent years have witnessed reports on pyeloplasty in infancy. This study presents the feasibility and outcome of pyeloplasty in neonates and infants from a single centre.

METHODS

The authors examined the records of 40 neonates and infants (46 renal units) who underwent pyeloplasty for ureteropelvic junction obstruction since 1988. Patient characteristics, clinical presentation, investigations, associated anomalies, age at surgery, operative technique and outcome were evaluated.

RESULT

The mean and median age at surgery was 3.5 and 2.5 months respectively, and mean postoperative hospital stay six days. Associated anomalies were found in 27% of infants and in some they influenced the outcome. In 72%, no stent or nephrostomy was used. However, all had a closed perinephric drain. There was no mortality in this series. Complications (8.7%) comprised anastomotic leak in three and anastomotic stricture in one unit. In 35 of 38 renal units, improved drainage and recovery of differential function was confirmed on postoperative renogram.

CONCLUSION

Where indicated, pyeloplasty in the neonate and infant will be readily adopted by specialists for the select few it would benefit. It is hoped that all those involved in the care of these infants will take cognisance of this fact to ensure early optimal management of ureteropelvic junction obstruction.

Antenatally detected, unilateral dilatation of the renal pelvis: a critical review. 1. Postnatal non-operative treatment 20 years on--is it safe?

BACKGROUND

Non-operative postnatal treatment of antenatally detected hydronephrosis, consistent with pyelo-ureteral obstruction, has functioned well during follow-ups of up to 17 years. However, doubts are still expressed and, admittedly, the final verdict on this new policy is still remote. The purpose of this review is to define the state of art and to serve as a background for future randomized clinical trials, which still are missing.

METHODS AND MATERIAL

From the literature, 6 patient series were chosen based on the following criteria: publication during the 1990s to allow for a longer follow-up and better diagnostic tools; consecutive patient series; and compliance with a 50-point form. Data, from 593 kidneys, were then pooled. Result of the compilation: Four hundred and seventy-four kidneys, with differential function >40%, were allocated to expectancy and followed for 2-144 (mean 23) months. Four hundred and twenty-five (90%) were successful, independent of presence of caliectasis. Forty-nine (10%) had delayed pyeloplasty, after which declined function mostly improved / normalized - similar to 108 kidneys with early pyeloplasty because of an initial differential function <40%. Hydronephrotic size and isotope wash out rate did not predict outcome.

CONCLUSIONS

These figures agree with other reports: few cross-overs and functional recovery also after delayed operations. Thus, so far, with a caveat for future deterioration, expectancy seems safe and promising, in unilateral and probably in bilateral cases with normal function, although perhaps not in solitary kidneys. Hopefully, this review, together with a forthcoming communication on long-term risks and urgent research needs, will help to design future randomized clinical trials.

Analysis of trends on serial ultrasound for high grade neonatal hydronephrosis

PURPOSE

We sought to validate the role of serial ultrasound studies for detecting and excluding obstruction in high grade neonatal hydronephrosis.

MATERIALS AND METHODS

Between January 1996 and December 1998 all patients with prenatally diagnosed hydronephrosis underwent a protocol of antibiotic prophylaxis, ultrasound and voiding cystourethrography. All reflux-free patients underwent diuretic renography. Patients with high grade isolated unilateral hydronephrosis were included in the study. They were followed with 3 serial ultrasound examinations every 3 months in year 1 of life, biannually in year 2 and yearly thereafter. The trends in the changes in these studies were studied.

RESULTS

Of the 153 patients 45 (29%) met study inclusion criteria. During a mean followup of 38 months (range 23 to 52) 16 patients (36%) who showed a trend of progressive hydronephrosis underwent pyeloplasty. The remaining 29 patients showed a trend of improvement in hydronephrosis. The drainage pattern on initial diuretic renography had only 63% sensitivity and 59% specificity for diagnosing obstruction. The same was true for the decrease in differential function of below 40% with 56% sensitivity and 66% specificity. Logistic regression analysis revealed that neither the initial grade of hydronephrosis on prenatal ultrasound nor the drainage-functional pattern on initial diuretic renography was a predictor of the subsequent need for pyeloplasty. All 16 patients who underwent pyeloplasty had improved or stabilized hydronephrosis after pyeloplasty.

CONCLUSIONS

A trend of progressive hydronephrosis on 2 consecutive serial renal ultrasound examinations serves as an early diagnostic sign of obstruction. Initial grade of hydronephrosis on initial ultrasound as well initial functional-drainage patterns on diuretic renography are not predictors of obstruction. Serial ultrasound is noninvasive and could replace serial invasive renal scans. Diuretic renal scans still have a role, especially as a baseline study to guide the frequency of serial ultrasound examinations.

Long-term followup of prenatally detected severe bilateral newborn hydronephrosis initially managed nonoperatively

PURPOSE

We determine the outcome of severe bilateral primary ureteropelvic junction type hydronephrosis detected prenatally and managed postnatally with an initially nonoperative protocol.

MATERIALS AND METHODS

A total of 19 newborns (38 kidneys) with prenatally diagnosed primary grade 3 to 4 bilateral hydronephrosis were followed nonoperatively for a mean of 54 months (range 14 to 187). If urinary obstruction with evidence of renal deterioration (decreased differential function and/or progressive hydronephrosis) occurred pyeloplasty was performed.

RESULTS

Pyeloplasty was required in 13 kidneys (35%) in 9 patients (bilateral 4, unilateral 5). Age at pyeloplasty ranged from 2 to 22 months (mean 6.5) in 12 patients and 64 months in 1. The remaining 25 kidneys were followed nonoperatively (bilateral 20, unilateral 5). At last followup the Society for Fetal Urology grade of hydronephrosis in kidneys followed nonoperatively was 0 to 2 in 21 and 3 in 4, compared to 0 to 2 in 9 and Society for Fetal Urology 3 in 4 kidneys treated with pyeloplasty. Mean followup required for the most severely hydronephrotic kidney to achieve maximum ultrasound improvement was 10 months (range 3 to 34) for kidneys followed nonoperatively and 14 months (4-31) for kidneys after pyeloplasty. Differential renal function was measured in each kidney pair and compared using the difference in percent function between the 2 kidneys. In the nonoperative group mean initial difference in percent function was 8% (range 6% to 20%) and mean final difference was 5% (2% to 8%). In the pyeloplasty group mean initial difference in percent function was 16% (range 8% to 30%) and mean final difference was 7% (2% to 16%). With close followup and prompt pyeloplasty renal function improved to greater than pre-deterioration levels in all kidneys.

CONCLUSIONS

These data represent the natural history of severe bilateral newborn hydronephrosis. Renal dilatation and function improve with time in most kidneys. Close followup is required in the first 2 years of life to identify the subgroup (35%) of children with obstruction that requires prompt surgery. Such an approach prevented permanent loss of renal function. Nonoperative management with close followup during the first 2 years appears to be a safe and recommended approach for neonates with primary bilateral ureteropelvic junction type hydronephrosis.

Functional and morphologic evaluation of congenital urinary tract dilatation by using combined static-dynamic MR urography: findings in kidneys with a single collecting system

PURPOSE

To assess combined static-dynamic magnetic resonance (MR) urography in the evaluation of congenital urinary tract dilatation in infants and children.

MATERIALS AND METHODS

Sixty-two patients with urinary tract dilatation underwent prospective examination with combined static-dynamic MR urography. A combination examination involved use of a static T2-weighted three-dimensional inversion-recovery fast spin-echo sequence and a dynamic T1-weighted two-dimensional fast field-echo sequence with gadopentetate dimeglumine-DTPA and furosemide application. Twelve additional patients underwent examination with only static MR urography. Thus, both image quality and morphologic features were assessed in 74 patients with the use of MR urography. The results were compared with those of ultrasonography and, when available, conventional urography or surgery. In 62 patients, the dynamic sequence was used to calculate split renal function from renograms generated from parenchymal regions of interest and to assess urinary excretion from whole-kidney renograms. Results were compared with those of diuretic renal scintigraphy (DRS) for split function (Spearman rank correlation coefficient) and urinary excretion (kappa coefficient).

RESULTS

Stenoses at the ureteropelvic (n = 33) and ureterovesical (n = 31) junctions and within the ureter (n = 3) and nonstenotic dilatation (n = 23) were clearly depicted, while the normal urinary tract (n = 51) was depicted in its entirety in 47 of 51 examinations. Image quality was considered good or excellent in 95% of the kidney-ureter units. For split renal function, dynamic MR urography and DRS showed significant correlation (r = 0.92, P <.001). For urinary excretion, MR urography and DRS showed strong agreement (kappa = 0.67), with concordant classification of urinary excretion in 59 (81%) of 73 abnormal kidney-ureter units and in all 47 (100%) normal kidney-ureter units.

CONCLUSION

Combined static-dynamic MR urography provides high-quality depiction of the urinary tract in infants and children, while allowing accurate determination of single-kidney function and reliable evaluation of urinary excretion.

Future expectations--what paediatric nephrologists and urologists await from paediatric uroradiology

Cooperation between paediatric nephrology/urology and paediatric radiology is essential for timely and correct diagnosis and therapy of kidney and urinary tract disorders. We need the direct contact between doctors before or after investigations, interdisciplinary discussions, and rapid access to the images. This should lead to optimal settings for investigations, a reduction of radiation burden and the number of investigations, and further improvement in the management of patients. Modern sonography including colour Doppler sonography, amplitude-coded Doppler sonography, and eventually 3D-ultrasound is and will be the method of choice as the basic, non-invasive investigation. These investigations should become the routine in all institutions. Refinement and standardisation of already established investigations are needed. Recently introduced investigations, like MRI, will have to show their impact on future diagnostic imaging. Future introduction of new non-invasive methods is welcome, e.g. to correctly diagnose vesicoureteral reflux without catheterisation/puncture of the bladder.

Imaging guided interventional procedures in paediatric uroradiology--a case based overview

OBJECTIVE

To describe the potential and application of interventional image guided procedures in the paediatric urinary tract.

PATIENTS AND METHODS

The different techniques are illustrated using case reports. The examples comprise established indications such as percutaneous nephrostomy for compromised kidneys in obstructive uropathy and infection, sonographic guided renal biopsy including monitoring or treatment of complications after biopsy, and evaluation and balloon dilatation of childhood renal artery stenosis. There are new applications such as treatment of stenosis in cutaneous ureterostomy or sonographically guided catheterism for deployment of therapeutic agents.

RESULTS

Generally, the procedures are safe and successful. However, complications may occur, and peri-/post-interventional monitoring is mandatory to insure early detection and adequate management. Sometimes additional treatment such as percutaneous embolisation of a symptomatic post biopsy arterio-venous fistula, or a second biopsy for recurrent disease may become necessary.

CONCLUSION

Imaging guided interventional procedures are performed successfully in a variety of diseases of the paediatric urinary tract. They can be considered a valuable additional modality throughout infancy and childhood.

Recovery from release of ureteral obstruction in the rat: relationship to nephrogenesis

BACKGROUND

Obstructive nephropathy is a major cause of renal insufficiency in infants and children. Despite release of unilateral ureteral obstruction (UUO) in the first five days of life in the rat, renal growth is impaired, while glomerular filtration rate (GFR) is preserved at one month, but decreases markedly by one year. To test the hypothesis that renal recovery from UUO depends on the stage of nephrogenesis at the time of relief of obstruction, renal recovery from relief of five days UUO following completion of nephrogenesis (days 14 to 19) was compared with UUO during nephrogenesis (days 1 to 5).

METHODS

Rats underwent UUO or sham operation at one day of age, with relief five days later. In additional groups of neonatal rats, the operation was at 14 days, with relief at 19 days. Three months later, blood pressure, GFR, urine flow, sodium and potassium excretion, and kidney weight were measured. In addition, the number of glomeruli, glomerular maturation, glomerular diameter, tubular atrophy, and interstitial fibrosis were determined in each kidney. The effects of five-day UUO on number of glomeruli was determined also in adult rats one month following relief of obstruction.

RESULTS

Three months following relief of UUO during days 14 to 19, renal growth was decreased by 50%, compared to a 30% reduction following relief of UUO during days 1 to 5 (P < 0.05). The number of glomeruli was reduced by approximately 50% regardless of the timing of UUO, but glomerular size was reduced only in rats with UUO from days 14 to 19. Blood pressure and tubular atrophy were increased, and GFR, urine flow, sodium and potassium excretion were decreased in the postobstructed kidney of both neonatal groups. In the adult rat, the five-day UUO did not result in a decrease in the number of glomeruli.

CONCLUSIONS

In the period immediately following nephrogenesis, the kidney is particularly susceptible to long-term injury from temporary UUO. This suggests that a delay in relief of significant ureteral obstruction should be avoided if diagnosed in the perinatal or neonatal period.

Successful early pyeloplasty in infants

BACKGROUND

Early pyeloplasty for the treatment of congenital ureteropelvic junction obstruction to maximize nephron salvage is justified only if potential hazards of operating on small infants are avoided.

METHODS

The records were analyzed of all infants who underwent pyeloplasty over a 5-year period. Open pyeloplasty was performed if collecting systems had deteriorated or were demonstrated to be obstructed; it was also performed for severe cases of hydronephrosis. Outcome of surgery in the younger infant (patients <2 months of age) was compared with the older infant group (patients >2 months of age). Preoperative evaluation in case of mild or moderate hydronephrosis was directed toward ruling out a non-obstructed collection system and included voiding cystourethrography, and serial ultrasonography and/or dual isotope diuretic renography. Postoperative assessment consisted of serial ultrasonography and/or nuclear imaging to confirm decompression and relief of obstruction.

RESULTS

A total of 24 pyeloplasties were performed on 22 patients in the younger infant group (two bilateral) and 30 were performed on 27 infants in the older infant group (three bilateral). The only significant differences between the groups were as follows: patients in the younger infant group were likely to present in utero (75%, p = 2.69), whereas those in the older infant group were more likely to present with a urinary tract infection (48%, p = 4.12). During follow-up examination, 23 renal units in the younger infant group and 24 in the older infant group were judged to be stable or improved. Four kidneys were not salvaged after pyeloplasty, one in the younger infant group and three in the older infant group.

CONCLUSIONS

Good results of pyeloplasties performed in the infants in this series support early correction of ureteropelvic junction obstruction in infants.

Clinical impact of differential renal function to indicate and assess pyeloplasty and the significance of coexisting vesicoureteral reflux

PURPOSE

In patients with ureteropelvic junction obstruction (JPJO) who are conservatively treated, 5% to 10% of them show a deterioration of renal function without recovery after delayed pyeloplasty. Should surgery be indicated based on observed deterioration of differential renal function (DRF)? Can we expect improvement of the DRF after pyeloplasty? What other influencing parameters may affect DRF?

MATERIALS AND METHODS

In this study, the authors examined 85 ureterorenal junctions that had undergone the Anderson-Hynes technique for surgical correction of UPJO. Based on the values obtained from the preoperative DRF (Tc-99m mercaptoacetyltriglycine), the cases were separated into three categories: group I had poor DRF (less than 11% of total renal function [TRF]), group II had moderate DRF (11% to 33% of TRF), and group III had adequate DRF (more than 33% of TRF). Twelve months after surgery, renal function was reassessed. The results were correlated with age at surgery, symptoms, coexisting vesicoureteral reflux, and drainage.

RESULTS

Seven ureterorenal junctions (8%) comprised group I, 15 (18%) comprised group II, and 63 (74%) comprised group III. After UPJO repair, 13% showed marked improvement in DRF, 86% remained stable, and 1% exhibited diminished function. In 50% of the renal cases with preoperative DRF less than 33%, postoperative improvement was seen. In follow-up renal scans, 30 cases (35%) revealed nonobstructive drainage, whereas the remaining 53 junctions (62%) showed moderate delayed drainage. Both the moderate delayed group (57%) and the nonobstructive group (50%) showed similar DRF improvement. Sixty-six percent of the patients with impaired DRF improved after pyeloplasty performed within the first 3 months of life, compared with 42.8% of patients in whom surgery was performed after 5 years of age. Vesicoureteral reflux was evident in 27.2% of the patients with preoperative impaired DRF compared with 11% with normal DRF. Forty-five percent of the patients with impaired DRF and no improvement after surgery had coexisting vesicoureteral reflux, compared with 9% of those with postoperative improvement.

CONCLUSIONS

Sustained renal impairment after pyeloplasty is likely as a result of preexisting renal dysplasia with vesicoureteral reflux. Moderate delayed drainage after surgery does not affect DRF. Surgery for UPJO should be indicated independent of a DRF follow-up (except very low DRF) or the age at the time of diagnosis.

Angiotensin converting enzyme inhibition worsens the excretory phase of diuretic renography for obstructive hydronephrosis

PURPOSE

A growing body of evidence identifies the renin-angiotensin system as a key factor in the onset and progression of renal damage in chronic partial obstruction, which often represents a complex diagnostic challenge. A prospective study was undertaken to evaluate the role of captopril mercaptoacetyltriglycine-3 (MAG-3) renography as an early diagnostic test of obstruction. We report the results in a subgroup of children who underwent surgical correction for pyeloureteral obstruction.

MATERIALS AND METHODS

Pyeloplasty was performed in 12 patients, including 10 males, 2 to 72 months old (median age 7) with unilateral hydronephrosis, including normal renal function and blood pressure. Basal and captopril enhanced diuretic renography with 99mtechnetium MAG-3 was performed within 24 hours using the same hydration and diuretic stimulus (0.75 mg./kg. furosemide), and 0.75 mg./kg. captopril was administered orally 60 to 90 minutes before scintigraphy.

RESULTS

No adverse effects or modifications of the blood pressure were observed after captopril administration. The diuretic response was deeply worsened by angiotensin converting enzyme inhibition in each hydronephrotic kidney even when the basal study was only slightly abnormal (15-minute washout basal -27 +/- 16%, after captopril -9 +/- 13, p <0.005). After surgical correction the diuretic washout during angiotensin inhibition appeared normal in all patients (15-minute washout -56 +/- 14%). Separate renal function and parenchymal transit of MAG-3 were not modified by angiotensin converting enzyme inhibition, preoperatively or postoperatively.

CONCLUSIONS

Our data confirm the influence of angiotensin on the kidney excretory system in human hydronephrosis and suggest a role for captopril enhanced diuretic renography in the early diagnosis of pyeloureteral obstruction. Further work is needed to evaluate angiotensin converting enzyme inhibition as a protective agent in obstructive nephropathy.

Angiotensin converting enzyme inhibition worsens the excretory phase of diuretic renography for obstructive hydronephrosis

PURPOSE

A growing body of evidence identifies the renin-angiotensin system as a key factor in the onset and progression of renal damage in chronic partial obstruction, which often represents a complex diagnostic challenge. A prospective study was undertaken to evaluate the role of captopril mercaptoacetyltriglycine-3 (MAG-3) renography as an early diagnostic test of obstruction. We report the results in a subgroup of children who underwent surgical correction for pyeloureteral obstruction.

MATERIALS AND METHODS

Pyeloplasty was performed in 12 patients, including 10 males, 2 to 72 months old (median age 7) with unilateral hydronephrosis, including normal renal function and blood pressure. Basal and captopril enhanced diuretic renography with 99mtechnetium MAG-3 was performed within 24 hours using the same hydration and diuretic stimulus (0.75 mg./kg. furosemide), and 0.75 mg./kg. captopril was administered orally 60 to 90 minutes before scintigraphy.

RESULTS

No adverse effects or modifications of the blood pressure were observed after captopril administration. The diuretic response was deeply worsened by angiotensin converting enzyme inhibition in each hydronephrotic kidney even when the basal study was only slightly abnormal (15-minute washout basal -27 +/- 16%, after captopril -9 +/- 13, p <0.005). After surgical correction the diuretic washout during angiotensin inhibition appeared normal in all patients (15-minute washout -56 +/- 14%). Separate renal function and parenchymal transit of MAG-3 were not modified by angiotensin converting enzyme inhibition, preoperatively or postoperatively.

CONCLUSIONS

Our data confirm the influence of angiotensin on the kidney excretory system in human hydronephrosis and suggest a role for captopril enhanced diuretic renography in the early diagnosis of pyeloureteral obstruction. Further work is needed to evaluate angiotensin converting enzyme inhibition as a protective agent in obstructive nephropathy.

Evaluation of sonographic renal parenchymal area in the management of hydronephrosis

PURPOSE

We used quantitative parameters of renal sonography to differentiate children with significant obstruction requiring surgical intervention from those without significant obstruction who were followed conservatively.

MATERIALS AND METHODS

We retrospectively reviewed the records of children who underwent evaluation for hydronephrosis. Those with a history of vesicoureteral reflux, anatomical abnormalities or neurogenic bladder were excluded from study. Patients were divided according to hydronephrosis grade into groups 1-grades III and IV followed conservatively, 2-grades III and IV requiring surgical intervention, 3-unilateral grade II and 4-bilateral. All images were scanned into a computer. Renal parenchymal and pelvic area was determined using National Institutes of Health image software. Parenchymal-to-pelvic area ratios were calculated from all images. We evaluated the ability of these measurements to determine the likelihood of surgical intervention.

RESULTS

The records of 81 children were available for analysis. Deterioration in parenchymal area growth was a predictor of surgical intervention. Such patients had catch-up growth of the affected kidney after pyeloplasty. A parenchymal-to-pelvic area ratio of greater than 1.6 on the initial ultrasound study after birth predicted cases that would need pyeloplasty in the future (p <0.05). No patient with grade II hydronephrosis required surgical intervention.

CONCLUSIONS

Following serial parenchymal area on serial ultrasound is useful for evaluating children with hydronephrosis. Those with a parenchymal area below the nomogram for growth usually require pyeloplasty. A parenchymal-to-pelvic area ratio of less than 1.6 on the initial ultrasound study after birth in patients with prenatally diagnosed ureteropelvic junction obstruction or on initial ultrasound in those diagnosed postnatally indicated the need for surgical intervention in this limited series.

Unilateral ureteral obstruction in neonatal rats leads to renal insufficiency in adulthood

BACKGROUND

Although unilateral ureteropelvic junction obstruction is the most common cause of congenital obstructive nephropathy in infants and children, management remains controversial, and follow-up after pyeloplasty is generally limited to the pediatric ages. We have developed a model of temporary unilateral ureteral obstruction (UUO) in the neonatal rat: One month following the relief of five-day UUO, the glomerular filtration rate (GFR) of the postobstructed kidney was normal despite a 40% reduction in the number of glomeruli and residual vascular, glomerular, tubular, and interstitial injury.

METHODS

To determine whether hyperfiltration and residual injury of remaining nephrons leads to progression of renal insufficiency in later life, 31 rats were sham operated or subjected to left UUO at one day of age, with relief of UUO five days later, and were studied at one year of age. GFR was measured by inulin clearance, and the number of glomeruli, tubular atrophy, glomerular sclerosis, and interstitial fibrosis were measured by histomorphometry in sham, obstructed (UUO), and intact opposite kidneys. Intrarenal macrophages and alpha-smooth muscle actin were identified by immunohistochemistry.

RESULTS

Despite relief of UUO, ultimate growth of the postobstructed kidney was impaired. The number of glomeruli was reduced by 40%, and GFR was decreased by 80%. However, despite significant compensatory growth of the opposite kidney, there was no compensatory increase in GFR, and proteinuria was increased. Moreover, glomerular sclerosis, tubular atrophy, macrophage infiltration, and interstitial fibrosis were significantly increased not only in the postobstructed kidney, but also in the opposite kidney.

CONCLUSIONS

Although GFR is initially maintained following relief of five-day UUO in the neonatal rat, there is eventual profound loss of function of the postobstructed and opposite kidneys because of progressive tubulointerstitial and glomerular damage. These findings suggest that despite normal postoperative GFR in infancy, children undergoing pyeloplasty for ureteropelvic junction obstruction should be followed into adulthood. Elucidation of the cellular response to temporary UUO may lead to improved methods to assess renal growth, injury, and functional reserve in patients with congenital obstructive nephropathy.

The long-term followup of newborns with severe unilateral hydronephrosis initially treated nonoperatively

PURPOSE

During the last decade it has become apparent that prenatally detected, unilateral severe hydronephrosis does not necessarily represent obstruction and may spontaneously improve or resolve postnatally. To define its natural history better we performed a long-term (mean 78 months) followup study of infants with hydronephrosis.

MATERIALS AND METHODS

A total of 104 newborns with antenatally diagnosed, primary, unilateral severe hydronephrosis were followed nonoperatively unless evidence of renal deterioration occurred for which pyeloplasty was performed.

RESULTS

All 23 infants (22%) who required pyeloplasty were younger than 18 months and had progressive hydronephrosis and/or reduction in differential renal function. Differential function exceeded predeterioration levels in all kidneys postoperatively. Of those cases followed nonoperatively hydronephrosis resolved in 69% and improved in 31%. Mean time to maximum improvement of hydronephrosis was 2.5 years. In 76% of those cases followed nonoperatively initial differential function was greater than 40% and final function averaged 49%. In the remaining 24% of cases differential function was less than 40% (mean 23%), and in an average of 18 months differential function increased to a mean of 47%. Initial half-time in nonoperative cases was greater than 30 minutes in 37%, 20 to 30 in 21% and less than 20 in 42%. Final half-time was greater than 30 minutes in 16%, 20 to 30 in 17% and less than 20 in 67%. Half-time was greater than 30 minutes in 87% of the patients and 20 to 30 in 4% before, and greater than 30 in 10%, 20 to 30 in 27% and less than 20 in 63% after pyeloplasty.

CONCLUSIONS

Unilateral newborn hydronephrosis appears to be relatively benign and in most instances dilatation and renal function improve with time. However, close followup is necessary to identify the subgroup of less than 25% of infants with obstruction because prompt pyeloplasty will prevent permanent loss of renal function. Standard tests for assessing obstruction in older patients appear to be invalid in infants because prolonged half-time and/or high grade hydronephrosis is neither an indicator of obstruction or surgery. Nonoperative treatment with close followup especially during the first 2 years is safe and recommended for these children.

Are preoperative parameters of unilateral pyelo-ureteric junction obstruction in children predictive of postoperative function improvement?

OBJECTIVES

Surgery on the pyelo-ureteric junction obstruction (PUJO) has long been thought to affect postoperative renal function. However, preoperative assessment of which kidneys will benefit from such surgery remains unreliable.

MATERIAL AND METHODS

Pre- and postoperative data relating to renal function were obtained by renal scan for 69 patients who were operated upon for PUJO. These patients were divided into two groups: group A (improved differential renal function) and group B (unimproved or decreased differential renal function). The two groups were then compared with regard to age at operation and presence or absence of clinical symptoms. Ultrasound (anteroposterior diameter of the pelvis, parenchymal thickness) and renal scan (glomerular filtration rate, differential renal function of the affected kidney, obstructive pattern) parameters were also taken into consideration. Some variables were also made dichotomous (pelvic diameter < or > 15 mm, parenchymal thickness < or > 5 mm, differential renal function < or > 40%). Statistical correlation was sought with parametric and non-parametric tests.

RESULTS

No correlation whatsoever was found between the two groups for any of the parameters under consideration, so that any attempt at logistical regression analysis failed.

CONCLUSIONS

None of the currently adopted diagnostic tests can be used to indicate which renal units will benefit from surgery through an improved renal function. The presence or absence of clinical symptoms does not appear to affect renal function either. There is evidence that parents should be provided with such information when giving their informed consent to pyeloplasty.

Renal expression of monocyte chemotactic protein-1 and epidermal growth factor in children with obstructive hydronephrosis

BACKGROUND/PURPOSE

The authors studied the potential role of ureteropelvic junction obstruction (UPJ-O) in causing progressive renal damage in children through the renal expression of epidermal growth factor (EGF) and monocyte chemotactic protein-1 (MCP-1) mRNA.

METHODS

Renal tissues were harvested from 11 children with UPJ-O and from 10 normal kidneys to study the renal expression of EGF and MCP-1 detected by means of in situ hybridization. Five of the patients were found to have a history of urinary tract infection (UTI).

RESULTS

Children with UPJ-O had marked reduction of EGF gene expression when compared with controls. Interstitial expression of MCP-1 mRNA was present in all UPJ-O cases. Both EGF and MCP-1 expression did not correlate with age, with differential renal function, and with renal thickness measured through MAG3 renal scan. Children with a history of UTI had a more severe reduction of the renal thickness of the affected kidney compared with those without UTI. MCP-1 expression was higher and EGF more reduced in children with a history of UTI.

CONCLUSIONS

Our results suggest a potential role of EGF and MCP-1 in the pathogenesis of renal damage and growth failure in UPJ-O, especially in children with UTI. These important functional changes begin early in life, possibly during fetal life.

Recovery following relief of unilateral ureteral obstruction in the neonatal rat

BACKGROUND

Obstructive nephropathy is a primary cause of renal insufficiency in infants and children. This study was designed to distinguish the reversible and irreversible cellular consequences of temporary unilateral ureteral obstruction (UUO) on the developing kidney.

METHODS

Rats were subjected to UUO or sham operation in the first 48 hours of life, and the obstruction was removed five days later (or was left in place). Kidneys were removed for study 14 or 28 days later. In additional groups, kidneys were removed at the end of five days of obstruction. Immunoreactive distribution of renin was determined in arterioles, and the distribution of epidermal growth factor, transforming growth factor-beta1, clusterin, vimentin, and alpha-smooth muscle actin was determined in tubules and/or interstitium. The number of glomeruli, glomerular maturation, tubular atrophy, and interstitial collagen deposition was determined by morphometry. Renal cellular proliferation and apoptosis were measured by proliferating cell nuclear antigen and the TdT uridine-nick-end-label technique, respectively. The glomerular filtration rate was measured by inulin clearance.

RESULTS

Renal microvascular renin maintained a fetal distribution with persistent UUO; this was partially reversed by the relief of obstruction. Although glomerular maturation was also delayed and glomerular volume was reduced by UUO, the relief of obstruction prevented the reduction in glomerular volume. Although relief of obstruction did not reverse a 40% reduction in the number of nephrons, the glomerular filtration rate of the postobstructed kidney was normal. The relief of obstruction did not improve tubular cell proliferation and only partially reduced apoptosis induced by UUO. This was associated with a persistent reduction in the tubular epidermal growth factor. In addition, the relief of obstruction reduced but did not normalize tubular expression of transforming growth factor-beta1, clusterin, and vimentin, all of which are evidence of persistent tubular injury. The relief of obstruction significantly reduced interstitial fibrosis and expression of alpha-smooth muscle actin by interstitial fibroblasts, but not to normal levels.

CONCLUSIONS

The relief of obstruction in the neonatal rat attenuates, but does not reverse, renal vascular, glomerular, tubular, and interstitial injury resulting from five days of UUO. Hyperfiltration by remaining nephrons and residual tubulointerstitial injury in the postobstructed kidney are likely to lead to deterioration of renal function later in life.

Neonatal hydronephrosis

With fetal abnormalities diagnosed during maternal ultrasound becoming more commonplace, the management of neonatal hydronephrosis has become one of the most interesting and controversial subjects in pediatric urology. Although it is recognized that obstruction must be treated, it is also clear that hydronephrosis may well exist without significant obstruction. Numerous experimental and clinical studies of the urinary tract have failed to lead to a clear consensus. Our approach consists of careful observation of patients with moderate hydronephrosis in well functioning kidneys. In patients with reduced function or a renal pelvic diameter of greater than 3 cm and dilated calyces, we lean more towards surgical intervention. Overall, an individualized approach is necessary.

Collagen studies for pediatric ureteropelvic junction obstruction

OBJECTIVES

Ureteropelvic junction (UPJ) obstruction is the most common form of urinary tract obstruction in pediatrics. There is controversy regarding the need for early surgical intervention in many patients with apparent neonatal UPJ obstruction. To demonstrate the differences in type and amount of collagen in adult and pediatric UPJ obstruction, collagen studies were performed.

METHODS

The experimental groups are 9 pediatric patients with UPJ obstruction and 13 adult patients with UPJ obstruction. Six patients with normal UPJ were assigned as controls for each experimental group. The collagen content of UPJ was quantitated by hydroxyproline analysis. Immunohistochemical staining and Western blotting for collagen types I and III were performed.

RESULTS

The collagen content of pediatric UPJ was significantly lower in value than that of adult UPJ (P < 0.05). Immunohistochemical staining revealed that collagen type I was located in interfascicular space and collagen type III was located in intrafascicular space in both age groups. In Western blotting the relative intensity of collagen type III for pediatric UPJ was weaker than that of adult groups.

CONCLUSIONS

These results suggest that a larger series of patients should be examined to determine whether quantitative analysis for collagen types I and III would provide some kind of prognostic test for UPJ outcome in pediatric patients.

Does delayed operation for pediatric ureteropelvic junction obstruction cause histopathological changes?

PURPOSE

We studied histopathological changes in kidneys with demonstrable ureteropelvic junction obstruction in relation to patient age, differential renal function and urinary tract infection.

MATERIALS AND METHODS

Renal biopsy was performed in 42 children (44 kidneys) with a mean age of 3 years 6 months who underwent open pyeloplasty due to ureteropelvic junction obstruction. Each specimen was examined for reversible inflammatory cell infiltration and irreversible change, including interstitial fibrosis, arteriolar thickening and glomerular sclerosis. Each pathological finding was scored 0 to 3 in increasing grades of severity, and correlated with patient age, differential renal function and history of urinary tract infection.

RESULTS

Of the 44 kidneys 20 (45%) had irreversible change. Correlation study revealed no association between patient age and histological findings, and there was no statistically significant difference in any histopathological category regardless of age. Differential renal function correlated with inflammatory cell infiltration and interstitial fibrosis. There were significantly worse histopathology scores in all categories when differential renal function was less than 30 versus 40% or greater. Interstitial fibrosis was significantly worse in the 30 to 40% group than in the greater than 40% group. The histopathological score of interstitial fibrosis was significantly higher in patients with than without urinary tract infection.

CONCLUSIONS

Early correction in infants with ureteropelvic junction obstruction may not be necessary when initial differential renal function is greater than 40%. However, any decrease in differential renal function or recurrent urinary tract infections despite antibiotic prophylaxis warrant surgical correction of obstruction.

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.

Ureteropelvic junction obstruction in children. Unique considerations for open operative intervention

The treatment of UPJ obstruction in children should be approached in a fashion that recognizes the differences between children and adults. Radiographic definition of the urinary tract is different in children than in adults because of the size of the child and technical difficulties with instrumentation. Retrograde pyelography, in general, is not necessary in children, although this decision must be individualized. The surgical incision should be chosen based on the size of the child and the unique considerations of individual renal anatomy and pathology, as well as the surgeon's experience. In children, tubeless surgery may be performed with excellent results, however, diversion with nephrostomies and stents may be necessary in selected cases. With attention to technical details and the unique considerations in children, the results of repair of the UPJ should be excellent and reproducible.

The pathophysiology of UPJ obstruction. Current concepts

It took more than half of a century for urologists to recognize that hydronephrosis is not necessarily equivalent to obstruction. Keeping this important truism in mind, particularly when dealing with antenatal hydronephrosis, one must also remember that hydronephrosis is not a normal condition. It is conceivable that although the initial intrinsic stenosis or ureterovascular obstruction may not be clinically significant in terms of renal functional damage, as compensatory renal pelvic dilatation develops, secondary obstructive elements may be recruited to create an insertional anomaly and peripelvic fibrosis. The individual types of UPJ obstruction that are seen in diagnostic studies or on the operating table may represent isolated "snapshots" of evolving pathophysiologic processes. If this is true, patients with asymptomatic congenital hydronephrosis, although lacking obvious renal function loss, require long-term follow-up.

Neonatal management of unilateral hydronephrosis. Role for delayed intervention

Hydronephrosis should be managed no differently in the newborn than in any other age group: UPJ obstruction should be surgically corrected as soon as the diagnosis is made. Unfortunately, the diagnosis of obstruction in the newborn with hydronephrosis is difficult and the traditional tests used in the older child or adult are not valid. Because newborn hydronephrosis is a relatively benign condition, surgical intervention should be delayed until the diagnosis of obstruction is proven. A protocol for evaluating the newborn with hydronephrosis is presented.