Renal function before and after pyeloplasty: does it improve?

Predictive Value of the Postural Difference in Antero-Posterior Diameter of Renal Pelvis on Ultrasonography of Unilateral Ureteropelvic Junction Obstruction in Determining the Need For Surgery

BACKGROUND

Ureteropelvic junction obstruction (UPJO) is the most common cause of antenatal hydronephrosis. Although majority of them improve with time, none of the existing diagnostic modalities can accurately predict which hydronephrotic kidney is at the risk of progressive renal damage and will benefit from early surgery. Postural variations in the anteroposterior pelvic diameter (APPD) of the hydronephrotic kidney in children during follow-up postnatal ultrasonography (USG) reflect the intrapelvic tension, which might help in predicting the need of surgery amongst these patients.

MATERIALS AND METHODS

We designed this prospective observational study in all unilateral UPJO patients on postural variation in the APPD of renal pelvis on ultrasonography. The mean age of all patients were 2.15 years (0-5 years) and managed at our institute at All India Institute of Medical Sciences, Bhubaneswar. The study duration was from July 2019 to May 2021. The management of these patients was done as per the standard institutional protocol and there was no deviation due to inclusion in this study. We documented the variations in postural APPD both amongst the conservatively managed group and the surgically managed group of patients. Linear correlation between two continuous variables was explored using Pearson's correlation (if the data were normally distributed) and Spearman's correlation (for non-normally distributed data).

RESULTS

We found a higher prone APPD than supine APPD in all these patients indicating the obstruction at ureteropelvic junction. However, in the surgical group, there was less variation in the postural APPD compared to the conservative group, and when there was no variation in the postural APPD, the need of surgery was 100%. The limitation of our study was the small sample size (n = 36). A study involving a larger population or involving multiple institutions may further add significance to our findings.

CONCLUSION

We found less postural variation in APPD on USG to be more likely associated with severe UPJO requiring early surgery. This may indicate a non-compliant renal pelvis. However, it was statistically not significant.

Does Age Influence the Functional Recovery after Infant Pyeloplasty?

Purpose

The purpose was to study the correlation between age at surgery and functional recovery after infant pyeloplasty.

Materials and Methods

All infants who underwent pyeloplasty were analyzed retrospectively in this multicenter study. Anteroposterior diameter (APD) >2 cm, split renal function (SRF) <40%, and Society of Fetal Urology (SFU) grade 3-4 were surgical indications. Based on the age at pyeloplasty, they were divided into Group 1 (1-3 months) and Group 2 (4-12 months). APD and SRF were compared before and after surgery in both groups. The fractional recoverable function (post-SRF-pre-SRF)/(50-pre-SRF) ×100 was correlated with age.

Results

Fifty-one infants underwent pyeloplasty (mean age: 1.6 months - Group 1 and 7.2 months - Group 2). The mean APD decreased from 3 cm to 1.2 cm in Group 1 while 2.8 cm to 2 cm in Group 2 (P = 0.001). The mean SRF increased from 32.28% to 42.81% in Group 1 while 31%-34.18% in Group 2. SRF recovery was significantly higher in Group 1 compared to Group 2 (P = 0.001). Regression analysis showed a weak negative correlation (r = -0.2792) between age at surgery and renal function improvement.

Conclusion

Functional recovery after pyeloplasty is better when done earlier (1-3 months), as this gives the growing kidney the best opportunity to recover.

Ten years of paediatric robotic surgery: Lessons learned

Background

Costs and a low total number of cases may be obstacles to the successful implementation of a paediatric robotic surgery programme. The aim of this study was to evaluate a decade of paediatric robotic surgery and to reflect upon factors for success and to consider obstacles.

Materials and Methods

All children operated on with robotic‐assisted laparoscopic surgery between 2006 and 2016 were included in a retrospective, single‐institutional study in Lund, Sweden.

Results

A total of 152 children underwent robotic surgery during the study time with the most frequent procedures being fundoplication (n = 55) and pyeloplasty (n = 53). Procedure times decreased significantly during the study period. Overall, 18 (12%) of the operations were converted to open surgery, and seven (5%) patients required a reoperation.

Conclusions

Despite a low volume of surgery, we have successfully introduced robotic paediatric surgery in our department. Our operative times and conversion rates are continuously decreasing.

Functional outcome after neonatal pyeloplasty in antenatally diagnosed uretero-pelvic junction obstruction

Background

With routine antenatal ultrasonography, fetal hydronephrosis is commonly diagnosed. This leads to early detection of postnatal uretero-pelvic junction obstruction which may require surgical intervention. But, there is no clear consensus in the benefits of operating these patients in the neonatal age.

Methods

Aim—To study the functional outcome after pyeloplasty in neonates with antenatally diagnosed unilateral uretero-pelvic junction obstruction (UPJO). Records of all neonates (N = 48) who presented between 2016 and 2018 with prenatal diagnosis of unilateral UPJO and underwent a Anderson-Hyne’s Pyeloplasty were retrospectively analyzed. Indications for surgery were SFU grade 3 or 4, a split renal function (SRF) < 40% on a diuretic renal scan and antero-posterior renal pelvic diameter (APD) > 2.5 cm with parenchymal thinning. Parenchymal thickness (PT) and APD measured by ultrasonography, and SRF measured by 99 m Tc-EC renal scan were compared before and after surgery.

Results

Our study comprised of 48 patients with 79.2% males (n = 38). UPJO affected the left side more (n = 30, 62.5%). The mean age at pyeloplasty was 28 days (range 26–30). The outcome was considered successful in 46 (95.84%) patients. The APD decreased from a mean of 3.5 cm APD preoperatively to 1.38 cm 1 year later which was statistically significant (p < 0.001). The PT increased from 3.95 to 7.1 mm 1 year postoperatively which was significant (p < 0.001). The drainage pattern and SRF improved in 46 (95.84%) patients. The SRF improved from a mean of 35.48–44.7% 1 year postoperatively which was significant (p < 0.001).

Conclusion

Pyeloplasty done in the neonatal age for prenatally diagnosed UPJO, having SFU grade 3–4 UPJO, leads to significant improvement of SRF and PT with minimal complications. Neonatal Pyeloplasty for significant UPJO is a safe procedure which provides the kidney maximum opportunity to improve function.

Renal functional improvement after pediatric pyeloplasty in kidneys with split renal function less than 20%: a single institute experience

Background

Pediatric pyeloplasty in ureteropelvic junction obstruction (UPJO) is indicated in renal impaired drainage or renal function deterioration. The improvement of renal function after pediatric pyeloplasty is still controversial in poorly functioning kidneys. Past studies on poorly functioning kidneys had a variable SRF specification, and these studies often had a limited number of patients so that they did not achieve statistical significance. The study aims to detect the renal functional improvement after pediatric Anderson-Hynes pyeloplasty (AHP) with split renal function (SRF) less than 20% (poor renal function).

Results

A retrospective study included 46 pediatric patients with unilateral UPJO who underwent open AHP with SRF < 20% on a renal isotope scan from August 2012 to October 2018. Success was defined based on either improvement in symptoms, improvement in drainage on postoperative renography, and/or improvement or stability in SRF on the renal scan done 6 months postoperatively and yearly thereafter. Deterioration of SRF by more than 5% was deemed to be deterioration. An increase in SRF of more than 5% was deemed to be an improvement.

A total of 46 patients with a mean age of 32 months with poor renal function on isotope renogram (SRF < 20%) were included. All patients had an obstructive pattern on the preoperative radionuclide scans. The median preoperative SRF was 9.26%. The mean (range) follow-up was 30 months. The success rate was 91.3%. Three patients underwent redo pyeloplasty, whereas a secondary nephrectomy was necessary for one. The remaining (42) patients showed stability or improvement of SRF with no further symptoms. Renal scintigraphy at 6 and 12 months after surgery revealed significantly increased SRF compared to preoperative one.

Conclusion

Poorly functioning renal unit with SRF < 20% can show functional improvement and recoverability after pediatric pyeloplasty.

Uretero-Pelvic Junction Stenosis: Considerations on the Appropriate Timing of Correction Based on an Infant Population Treated with a Minimally-Invasive Technique

There is no univocal consensus about timing of intervention and best surgical approach for infants with asymptomatic uretero-pelvic junction obstruction (UPJO). We conducted a retrospective analysis of patients undergoing one-trocar-assisted pyeloplasty (OTAP) in a 13 year range period by creating two homogenous groups (indications for surgery were the same for all patients): patients operated on in the first 90 days of life (34 patients; Group 1) and patients operated on between 3 and 12 months of life (34 patients; Group 2). We observed no statistically significant differences between groups in regard to mean operative time, conversion rate to open surgery, mean hospital stay, early complications (urinary leakage) rate and mean antero-posterior diameter (APD) reduction rate. Moreover, no statistical improvement was seen between groups in regard to separate renal function (SRF) at 1-year-follow-up renogram. Thanks to the HSS calculated before and 1 year after surgery, we registered an important improvement in Group I patients (p = 0.023). In our study, there was no significant evidence, in terms of intraoperative data and early postoperative outcomes, between patients who underwent an early pyeloplasty and those who underwent a delayed correction. Nevertheless, we registered a significant improvement in those patients with an impaired SRF that underwent an early surgical correction, especially in terms of urinary flow. Even though this study cannot definitely establish the superiority of early timing of correction, it is evident that further research is needed to clarify this aspect.

Functional, morphological and operative outcome after pyeloplasty in adult patients: Laparoscopic versus open

OBJECTIVE

The aim of this study is determine and compare improvement of hydronephrosis, renal function, and operative outcome between laparoscopıc and open pyeloplasty in adults.

MATERIAL AND METHODS

Sixty-five adult patients with primary ureteropelvic junction obstruction (UPJO) underwent pyeloplasty between January 2014 and September 2020. Thirty-four patients had laparoscopıc pyeloplasty (LP), 31 patients had open pyeloplasty (OP). In this retrospective study demographics, differential renal function (DRF), hydronephrosis, anteroposterior diameter of pelvis renalis (APD) and operative outcomes: operation time, blood loss, complications, hospital stay, etiology, analgesic requirement, complications, and success rates were compared between two groups.

RESULTS

Improvement of APD is higher in OP group (p: 0.001). Improvement of DRF (p: 0.713) and hydronephrosis (p = 1.000), success (p: 0.407) and complication rate (p: 0.661) are comparable between two groups. Median hospital stay, postoperative analgesia requirement and blood loss was less in LP group, mean operative time was shorter in OP group (p: 0.001).

CONCLUSION

Pain complaints are greatly reduced after pyeloplasty in adult patients but the drainage of kidney, DRF and hydronephrosis does not improve as much as desired. Improvement of APD is better and median operative time is less in OP, intraoperative blood loss, hospital stay, and analgesic requirement is less in LP group in our study.

Laparoscopic pyeloplasty as an alternative to nephrectomy in adults with poorly functioning kidneys due to ureteropelvic junction obstruction

OBJECTIVES

To evaluate outcomes of laparoscopic pyeloplasty (LP) in adults with poorly functioning kidney due to ureteropelvic junction obstruction (UPJO).

METHODS

A retrospective comparative analysis was performed between adult patients who underwent LP due to UPJO with differential renal function (DRF) ≤ 15% and DRF > 15%. LP success rate and complications were assessed. LP success was defined as symptoms improvement and DRF improvement or stabilization. DRF and estimated glomerular filtration rate (eGFR) were analyzed before and 12 months after surgery to evaluate renal function recovery. DRF was estimated using Tc-99 m DMSA renal scintigraphy.

RESULTS

Among 121 LP performed in the study period at our institution, 15 and 42 were included in the DRF ≤ 15% and DRF > 15% groups, respectively. At a median follow-up of 17.8 months, all patients with DRF ≤ 15% reported symptoms improvement. LP success rate was 86.7% and 90.5% (p = 0.65) for patients with DRF ≤ 15% and DRF > 15%, respectively. There were no complications in the DRF ≤ 15% group, while there were three complications recorded in the DRF > 15% group (Clavien 2 and 3b). In the DRF ≤ 15% group, mean pre-operative and post-operative DRF was 9.5% ± 3.6 and 10.5% ± 7.8 (p = 0.49), respectively. Median pre-operative and post-operative eGFR was 68.5 ml/min and 79.8 ml/min (p = 0.93), respectively. Two patients had DRF improvement after LP.

CONCLUSIONS

LP in adult patients with UPJO and poor function kidneys is an effective and safe procedure. DRF recovery is seen in a minority of the patients; however, LP is an alternative to nephrectomy.

Diuresis renography in the evaluation and management of pediatric hydronephrosis: What have we learned?

Diuresis renography (DR) is widely used in the evaluation of hydronephrosis and hydroureter in infants and children. The goal of this provocative nuclear imaging examination should be to detect the hydronephrotic kidneys at risk for loss of function and development of pain, hematuria, and urinary tract infection. The reliability of DR is dependent on the acquisition and processing of the data as well as interpretation and utilization of the results. In this review, the key concepts of standardized DR and pitfalls to avoid are highlighted.

Retroperitoneal laparoscopic non-dismembered pyeloplasty for uretero-pelvic junction obstruction due to crossing vessels: A matched-paired analysis and review of literature

OBJECTIVE

To compare laparoscopic Anderson-Hynes pyeloplasty (LAHP) and retroperitoneal laparoscopic YV-pyeloplasty (LRYVP) in ureteropelvic junction obstruction (UPJ) in presence of a crossing vessels (CV).

METHODS

Our database showed 380 UPJO-cases,who underwent laparoscopic retroperitoneal surgery during the last 2 decades including 206 non-dismembered LRYVP, 157 dismembered pyeloplasties LAHP, and 17 cases of laparoscopic ureterolysis. Among them 198 cases were suitable for a matched-pair (2:1) analysis comparing laparoscopic retroperitoneal non-dismembered LRYVP (Group 1, n = 131) and dismembered LAHP (Group 2, n = 67) in presence of a crossing vessel. Patients were matched according to age, gender, kidney functions, and obstruction grade. Complications were graded according to modified Clavien-classification.

RESULTS

Comparative data were similar between both groups (LRYVP vs. LAHP) including mean operating time (112 min vs. 114 min), complication rates (4.2% vs. 7.3%) mainly Grade 1-2 according to Clavien classification, and success rates (90% vs. 89%). These results reflected in the reviewed literature indicate that LRYVP provides the advantage of minimal dissection in case of CV with similar outcome. However, redundant pelvis and anteriorly crossing vessels still require a dismembered pyeloplasty LAHP.

CONCLUSION

LRYVP has achieved similar results compared with the previous golden standard of open surgery, especially in case of crossing vessels apart from presence of a redundant pelvis or anteriorly crossing vessel. This can be further improved when using the small access retroperitoneoscopic technique respectively mini-laparoscopy.

Determination of threshold value for follow-up of isolated antenatal hydronephrosis detected in the second trimester

INTRODUCTION

Isolated antenatal hydronephrosis (ANH), defined as a dilation of the renal pelvis (≥5 mm), is one of the most common abnormalities detected on prenatal ultrasound. However, established cut-off values for postnatal follow-up differ between countries and are based on little evidence. The current protocol in the Netherlands for follow-up might be too conservative.

OBJECTIVE

To assess the applicability of a higher threshold for follow-up of isolated antenatal hydronephrosis (ANH) than the current practice, without the risk of missing significant postnatal urinary tract obstruction.

STUDY DESIGN

Retrospective case series on all fetuses with isolated ANH (anteroposterior pelvic diameter (APPD) ≥5 mm) at the second trimester anomaly scan, and diagnosed between 2000 and 2009, in relationship to renal outcome.

RESULTS

A total of 279 infants with second trimester isolated ANH were included. In 201/279 (72%) fetuses, ANH had normalized (APPD <10 mm) before the third trimester scans. Hydronephrosis persisted postnatally in a minority of 56/279 (20.1%). Postnatal assessment showed signs of obstruction in 41/279 (14.7%) infants, duplicated collecting system or vesicoureteral reflux (VUR). Surgery was performed in 18/279 (6.5%) infants. A non-functioning kidney was shown in 6/279 (2.2%) infants with ANH. Mild ANH (APPD <7 mm) during the second trimester (172/279 (61.6%)) never resulted in surgery for renal anomalies or non-functioning kidney. Infants with an APPD ≥10 mm in the second trimester were far more likely to develop renal anomalies or undergo surgery compared with infants with an APPD 7-10 mm. The number of non-functioning kidneys was too low to be conclusive.

CONCLUSIONS

Follow-up ultrasounds for isolated ANH ≥7 mm instead of ≥5 mm at the second trimester scan would have saved 62% of third trimester scans, without missing any infant with a non-functioning kidney, significant obstruction or symptomatic VUR. In view of the results, it is reasonable that referral for follow-up of second trimester ANH is not strictly indicated in cases with an APPD <7 mm.

Predictors of Renal Functional Improvement After Pyeloplasty in Ureteropelvic Junction Obstruction: Clinical Value of Visually Assessed Renal Tissue Tracer Transit in 99mTc-mercaptoacetyltriglycine Renography

OBJECTIVE

To determine the clinical value of visually assessed renal tissue transit time (TTT) in ^99mTc-mercaptoacetyltriglycine (^99mTc-MAG3) renography for patients undergoing pyeloplasty.

MATERIALS AND METHODS

Medical records of 164 patients who underwent dismembered pyeloplasty were retrospectively reviewed. Baseline and postoperative renal ultrasonography and ^99mTc-MAG3 renography were performed. Two urologists blinded to clinical data evaluated the renography and classified TTT as timely or delayed based on visualization of the tracer in the kidney pelvis between 2 and 10 minutes. Renal functional change after pyeloplasty was compared between patients in the timely and delayed groups.

RESULTS

A total of 126 patients (median age, 9 months) were evaluated after excluding patients with bilateral ureteropelvic junction obstruction, a single functioning kidney, duplicated ureter, or <3 months of follow-up. There were no differences between 89 patients with timely TTT and 37 patients with delayed TTT in mean preoperative hydronephrosis grade (3.7 vs 3.8) and pelvic diameter (3.1 cm vs 3.4 cm). Although the pre- and postoperative mean values of differential renal function (DRF) were significantly higher in the timely group than in the delayed group (47.2% vs 38.3% and 47.9% vs 44.6%), DRF change was greater in the delayed group (6.3% vs 0.6%). In multivariate analysis, delayed TTT was the only significant predictor of >5% improvement in renal function after pyeloplasty.

CONCLUSION

Delayed TTT in ^99mTc-MAG3 renography was a significant predictor of renal functional improvement after pyeloplasty in ureteropelvic junction obstruction. Because substantial improvement of renal function is anticipated, we recommend immediate pyeloplasty in patients with delayed TTT and decreased DRF.

Outcome analysis of pediatric pyeloplasty in units with less than 20% differential renal function

OBJECTIVE

This study was conducted to assess ureteropelvic junction obstruction (UPJO) units with differential renal function (DRF) ≤20%, 3 months post-pyeloplasty as well as complications and stability of function in long term follow up.

MATERIAL AND METHODS

In this prospective study, children below 12 years age with unilateral UPJO and DRF ≤20% undergoing open Anderson-Hynes dismembered pyeloplasty from 2002-2014 excluding associated vesicoureteric reflux were included. Drainage and function were assessed with isotope [ethylene di-cysteine (EC)] scan at 3 months and later during yearly follow-up as well as by intravenous urography (IVU).

RESULTS

Of a total 744 patients with UPJO in the study period, 112 had DRF ≤20%. Thirty four (30%) underwent percutaneous nephrostomy. Ten with no function underwent nephrectomy. 102 (mean age 4.7 years) with DRF 0-9% (n = 40) and 10-20% (n = 62) formed the study group. Hypertension (3), small kidney (13) and crossing vessels (9) were associated. Follow up ranged from 1-8 years (4.6 ± 1.34 years). Six patients were lost to follow up. There was significant improvement in drainage in the remaining 96 patients. Mean DRF and IVU function showed highly significant improvement (p < .001) in those with clinical signs and symptoms (n = 85), compared to asymptomatic patients in preoperative 0-9% and 10-20% group. The mean rise in DRF was significantly more in the preoperative 0-9% group, palpable mass presentation and by age at 5-12 years in the 0-9% group and 1-5 years in the 10-20% group. In the symptomatic group, except for intermittent UTIs (n = 8) and pain (n = 3) which subsided 1-2 years after surgery, all patients had resolution of initial complaints. Hypertension resolved in two patients with crossing vessels. No patient required re-do pyeloplasty or developed hypertension during followup. There was no significant difference (p = 1.000) in mean DRF between 3 month and 1-8 years post-operative scans (n = 53).

CONCLUSIONS

This study which appears to be the largest in the literature of pediatric UPJO with DRF ≤20%, conclusively shows that there is statistically significant improvement in function after pyeloplasty which remains stable during the period of growth with no long term complications. Nephrectomy should be considered only in patients with nil or <5% uptake on isotope imaging with associated (a) no parenchyma on imaging or on exploration, (b) pyonephrosis, (c) hypertension or (d) minimal urine output on percutaneous nephrostomy.

The risk factors and clinical significance of acute postoperative complications after unstented pediatric pyeloplasty: a single surgeon's experience

PURPOSE

To analyze the risk factors and clinical significance of postoperative complications after unstented pediatric pyeloplasty.

MATERIALS AND METHODS

We analyzed 285 kidney units (KUs) on which unstented pyeloplasty was performed between April 2002 and March 2010. Measures included preoperative factors, postoperative complications, change in postoperative differential renal function (DRF), and failure of pyeloplasty. Risk factors for acute complications requiring additional ureteral stenting and decreased DRF were analyzed.

RESULTS

During a median follow-up period of 67.0 months, an additional ureteral stenting was required in 28 KUs (9.8%) due to the development of acute postoperative complications after unstented pyeloplasty. The incidence of complications increased significantly as preoperative DRF increased. DRF of more than 60% was the only independent risk factor for acute complications. Postoperative decrease in DRF was observed in 58 KUs (22.4%) among 259 KUs analyzed. Pyeloplasty failure was observed in 10 KUs (3.5%). The development of acute complications was not a risk factor for a decrease in DRF or pyeloplasty failure.

CONCLUSIONS

Urinary diversion during pyeloplasty is not related to a decrease in DRF or pyeloplasty failure. However, in patients with a preoperative DRF of greater than 60%, diversion could be considered due to the high prevalence of complications.

Renal pelvis reduction during dismembered pyeloplasty: is it necessary?

OBJECTIVE

To compare treatment results in patients who underwent pyeloplasty with and without pelvic reduction for ureteropelvic junction obstruction (UPJO).

METHODS

This randomized prospective study involved 40 patients, all diagnosed with unilateral UPJO; 20 each were randomly selected to undergo open dismembered pyeloplasty with pelvic reduction (group A) or pelvis-sparing pyeloplasty (group B). Patients were evaluated with ultrasound and DPTA renography scans 6 months postoperatively. Mean follow-up was 9 months.

RESULTS

The mean age in group B was 5.71 ± 6.36 years; in group A it was 4.81 ± 6.78 years. There was a decrease in mean anteroposterior renal pelvic diameter (from 49.9 to 26.35 ± 0.949 mm in A and 50.9 to 30.8 ± 1.556 mm in B) with improvement of split renal function (from 39 ± 22.47% to 42.4 ± 22.13% in A and 34.92 ± 16.79% to 38.8 ± 19.66% in B), glomerular filtration rate (from 37.25 ± 15.33 to 41.7 ± 19.34 ml/min in A and 31.3 ± 18.50 to 38.1 ± 23.23 ml/min in B) and draining curves on the 6-month scans, but without any significant difference between groups (p > 0.05). Two cases in group A and three in group B needed redo pyeloplasty, but without any significant difference in failure rate.

CONCLUSION

Excision of the pelvis is not necessary in dismembered pyeloplasty procedures. We had similar surgical outcomes for patients with or without pelvis reduction.

Relative renal function does not improve after relieving chronic renal obstruction

Study Type - Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? Technetium-99m MAG3 renography can be used to quantify relative renal function (RRF). Deterioration of renal function occurs with chronic obstruction. Small studies have previously shown that RRF is not improved in adult patients after pyeloplasty. Some studies have suggested that patients with higher preoperative RRF are more likely to improve. To our knowledge, these data represent the largest review of cases related to this subject. This study verifies past studies' assertions that RRF does not improve after relief of chronic renal obstruction. Using multivariable analysis, we identify lower age and lower preoperative RRF as predictors of >7% improvement in RRF. These data suggest that the aim of relieving obstruction should be to maintain RRF and alleviate symptoms, but not to seek improvement in overall renal function.

OBJECTIVE

To determine the change in relative renal function (RRF) after relief of chronic obstruction in adults.

PATIENTS AND METHODS

We retrospectively identified 85 adult patients who underwent scintigraphic diuretic renography before and after an intervention to relieve chronic unilateral renal obstruction. Patients were stratified into groups of low (<20%), medium (20-40%) and high (>40%) preoperative RRF in the obstructed kidney. Each group was assessed for change in RRF after relief of obstruction. We performed multivariable logistic regression analysis to determine whether age and pre-procedural RRF predicted a >7% improvement in RRF, controlling for medical comorbidities and type of obstruction.

RESULTS

The mean (sd) patient age was 43.6 (16.8) years and 66% of patients were female. The mean (sd) pre- and postoperative RRF values were not significantly different (37.6 [12.3] % vs 38.4 [13.6] %; P = 0.31). Patients stratified by low, medium and high preoperative function showed no significant change in postoperative RRF (P = 0.53, 0.39 and 0.77, respectively). In multivariable logistic regression analysis, younger age (odds ratio [OR] 0.90, 95% confidence interval [CI] 0.83-0.98) and lower preoperative RRF (OR 0.90, 95% CI 0.83-0.97) predicted improvement in RRF of >7%, after adjustment.

CONCLUSIONS

RRF does not significantly increase after relief of chronic obstruction. The goals of relieving chronic renal obstruction should be to maintain renal function and relieve symptoms, but not to regain renal function.

Unilateral anomalies of kidney development: why is left not right?

Abnormal renal development results in congenital anomalies of the kidney and urinary tract. As many studies suggest that renal malformations are more often found on the left side, a meta-analysis was performed on the distribution of five different unilateral anomalies: multicystic dysplastic kidney, renal agenesis/aplasia, renal ectopia, pelviureteral junction obstruction, and non-obstructive non-refluxing megaureter. Of these anomalies, the left side was affected in 53%, 57%, 56.9%, 63.2%, and 62.5% of patients, respectively, significantly different when compared with an anticipated 50% of left-sided anomalies. An exception to this left-side predominance was found in females with combined genital anomalies and unilateral renal agenesis that commonly present on the right side. The exact mechanisms leading to these lateralizations remain to be determined but may involve vascular development, differential gene expression, or susceptibility to environmental factors such as hypoxia. This remains largely speculative, however, illustrating our limited knowledge of embryogenesis in general and nephrogenesis in particular.

Long-term follow-up and management of prenatally detected, isolated hydronephrosis

PURPOSE

The aim of the study was to determine the outcome and management of infants with isolated hydronephrosis, detected prenatally and confirmed postnatally.

MATERIALS AND METHODS

Between January 1988 and January 2008, the files of 629 children (492 males and 137 females), who were diagnosed prenatally with isolated, unilateral hydronephrosis, and the diagnosis was confirmed postnatally, were retrospectively reviewed. The median follow-up time was 142 months. Serial ultrasonography and isotope diuretic renography nuclear imaging were performed. Hydronephrosis was assessed and classified according to the Society of Fetal Urology (SFU) grading system.

RESULTS

Initially, all of the children were treated conservatively. Stabilization occurred in all children with grade 1 hydronephrosis, in 87% of children (144) with grade 2 hydronephrosis, and in 30% of children (37) with grade 3 hydronephrosis. However, 13% of children (21) with grade 2 hydronephrosis, 70% of children (85) with grade 3 hydronephrosis, and 100% of children with grade 4 hydronephrosis received surgical intervention according to our predetermined criteria. Ninety-five patients (late pyeloplasty group) were treated for a reduction for a differential renal function (DRF) to less than 40%, and 80 children (early pyeloplasty group) underwent surgery for a DRF more than 40%, but hydronephrosis progressed to higher grades or failed to improve and had poor radiotracer clearance. Significant improvements after pyeloplasty were noted in both groups with respect to the DRF and the ratio of the depth of the calyces to the thickness of the parenchyma (C/P ratio; P < .0001). The improvement in DRF was greater in the late pyeloplasty group than the early pyeloplasty group (P = .044), whereas the improvement in the C/P ratio was greater in the early pyeloplasty group than the late pyeloplasty group (P = .001). The ipsilateral DRF was preserved in the early pyeloplasty group, whereas the ipsilateral DRF was still less than 40% in the late pyeloplasty group. The improvement in DRF was significant during the first year postoperatively and became stable thereafter. The C/P ratio was inversely correlated with the DRF in the patients before and after pyeloplasty (r = -0.257; P = .01; and r = -0.616; P = .001, respectively).

CONCLUSIONS

All infants with SFU-1 and most infants with SFU-2 hydronephrosis have relatively benign conditions and do not need an invasive procedure. Although greater improvement occurred in patients with an initial DRF less than 40%, the reduced DRF did not recover to the predeterioration level postoperatively. Earlier surgical intervention after a short period of strict clinical surveillance is beneficial for preserving renal function for patients with persistent SFU-3 or SFU-4 hydronephrosis.

The effects of ureteral mobilization and transection on ureteral oxygenation

OBJECTIVES

To determine the impact of ureteral transection with and without prior ureteral mobilization on ureteral oxygen partial pressure (p(u)O(2)).

METHODS

Sixteen pigs underwent general anesthesia with laparoscopic transperitoneal access to the right ureter. With no dissection and minimal manipulation, a tissue oxygen probe (Licox, Kiel, Germany) was introduced via a trocar and inserted into the ureter. The probes were placed at the ureteropelvic junction (UPJ, n = 8) and ureterovesical junction (UVJ, n = 8). Baseline p(u)O(2) was measured. Subsequently, half of the animals at each level (n = 4) underwent complete ureteral transection proximal to UPJ probes and distal to UVJ probes with or without prior mobilization. p(u)O(2) levels were measured after ureteral mobilization and transection.

RESULTS

Of the ureters transected at the UPJ without mobilization, the mean p(u)O(2) level declined by 13 mm Hg relative to baseline (P = 0.07). The baseline UPJ p(u)O(2) level declined by 5 mm Hg after ureteral mobilization alone and subsequently by 31 mm Hg after transection (P <0.01). Of the ureters transected at the UVJ without mobilization, the p(u)O(2) level decreased by 4 mm Hg relative to baseline (P = 0.08). The baseline UVJ p(u)O(2) level decreased by 15 mm Hg after ureteral mobilization alone and subsequently by 39 mm Hg after transection (P <0.01). At both the UPJ and UVJ, the transected-only p(u)O(2) level was statistically higher than the mobilized and transected level (P = 0.03, respectively).

CONCLUSIONS

During ureteral surgery, mobilization alone exposes the distal ureter to more ischemia than the proximal ureter, and efforts to minimize ureteral mobilization when transection is necessary are crucial in maintaining tissue oxygenation.

International Scientific Committee of Radionuclides in Nephrourology (ISCORN) consensus on renal transit time measurements

This report is the conclusion of the international consensus committee on renal transit time (subcommittee of the International Scientific Committee of Radionuclides in Nephrourology) and provides recommendations on measurement, normal values, and analysis of clinical utility. Transit time is the time that a tracer remains within the kidney or within a part of the kidney (eg, parenchymal transit time). It can be obtained from a dynamic renogram and a vascular input acquired in standardized conditions by a deconvolution process. Alternatively to transit time measurement, simpler indices were proposed, such as time of maximum, normalized residual activity or renal output efficiency. Transit time has been mainly used in urinary obstruction, renal artery stenosis, or renovascular hypertension and renal transplant. Despite a large amount of published data on obstruction, only the value of normal transit is established. The value of delayed transit remains controversial, probably due to lack of a gold standard for obstruction. Transit time measurements are useful to diagnose renovascular hypertension, as are some of the simpler indices. The committee recommends further collaborative trials.

Evaluation of UPJ obstruction before and after pyeloplasty using MR urography

This article builds on the previous article in this symposium and shows how MR urography contributes to the postoperative evaluation of children with UPJ obstruction. By analyzing the postoperative results, we derived new insights into their preoperative evaluation. With MR urography we combine simultaneous physiological and anatomic evaluation that enables us to identify changes in renal pathophysiology that occur in association with impaired drainage and obstruction. We studied 35 children before and after pyeloplasty. The pyeloplasty was considered successful in 30 and unsuccessful in 5. Both anatomic and functional criteria were used. The anatomic parameters included the degree of hydronephrosis, the appearance of the renal parenchyma, the quality of the nephrogram and the presence of crossing vessels. The functional criteria included the renal transit time, the calyceal transit time, the volumetric differential function, the Patlak differential function, the difference between the volumetric and Patlak differential function and the Patlak number per milliliter of renal tissue. No single parameter was sufficient to fully characterize UPJ obstruction, but by synthesizing all the information we were able to subdivide UPJ obstruction into compensated, decompensated and uropathic kidneys. Decompensated systems had the most significant improvement following successful pyeloplasty. Compensated systems showed little improvement in renal function, and uropathic kidneys were associated with a poor prognosis. It is clear that not all UPJ obstructions are the same, and it seems logical that treatment should be individually tailored rather than using a standard approach for all cases. Because MR urography can identify pathophysiological differences in children with UPJ obstruction that are occult to renal scintigraphy, it has an important potential role in identifying those who will benefit most from pyeloplasty and those who are probably best observed.

The prognostic value of relative renal function greater than 51% in the pelvi-ureteric junction-obstructed kidney on 99mtechnetium mercaptoacetyltriglycine study

OBJECTIVE

Obstructed kidneys with relative function (RRF) estimates >50% are occasionally noted in (99m)technetium mercaptoacetyltriglycine renal studies. It is thought that increased RRF might confer some benefit and/or permit delayed intervention. We compared the RRF and absolute renal function, as defined by effective renal plasma flow (ERPF), of obstructed kidneys in the ranges >51%, 40%-50% and <40% RRF before and after pyeloplasty.

METHODS

Twenty children, median age 13.5 months (range 3 weeks-126 months), satisfied criteria for the diagnosis of PUJ obstruction and estimated function >51% (group 1). Their pre- and post-intervention data were compared with 21 children, median age 2 months (range 1 week-126 months), with PUJ obstruction and 40%-50% RRF (group 2); and 21, median age 6 months (range two days-110 months), with RRF below 40% (group 3). Kidneys showing signs of continuing obstruction after surgery were excluded.

RESULTS

Final ERPF was negatively related to age: younger children, and those with a higher preoperative ERPF, recovered better than older children and those with a lower ERPF (p<0.05). Pre- and postoperative mean ERPF in group 1 was 76 (range 21-203) and 102 (6-240) ml/min/1.73 msq respectively. In group 2, these values were 75.2 (30-187) and 130.9 (44-306) ml/min/1.73 msq, and they were 42.6 (5-179) and 80.2 (17-205) ml/min/1.73 msq in group 3. When adjustment was made for preoperative ERPF, there was no evidence that RRF grouping was related to ERPF outcome. The postoperative ERPF of seven of 20 kidneys from group 1 (>51%) was lower than the ERPF before surgery compared to 2/21 in group 2 and 4/21 in group 3, but these differences were not statistically significant (p=0.25).

CONCLUSIONS

Most kidneys in each functional range improved when obstruction was relieved. An RRF >51% in the obstructed kidney was not always prognostically beneficial, and may be a warning of impending decompensation in a minority.

[Prenatal diagnosis of hydronephrosis: utility of diuretic renography]

OBJECTIVE

To investigate the value of diuretic renography in patients with prenatally diagnosed unilateral hydronephrosis.

MATERIAL AND METHOD

We reviewed 44 patients who underwent ultrasonography in the first week of life and 1 month after birth, and cystography and diuretic renography at 1 month to evaluate differential renal function and the diuretic washout pattern. Patients with vesicoureteral reflux were followed-up according to the protocol for this disorder. In the remaining patients, ultrasonography and/or diuretic renography was performed every 3-6 months.

RESULTS

In 4/44 patients vesicoureteral reflux was detected as cause a of hydronephrosis. In the remaining 40 patients, diuretic renography showed a washout pattern not suggestive of obstruction in 32 (only one patient needed surgery due to pyohydronephrosis). An indeterminate washout pattern was detected in one patient (who required surgery due to worsening of the washout pattern). A pattern suggestive of obstruction was detected in seven patients, four of whom required surgery (three due to a decrease in differential renal function and one due to worsening of the degree of pelvic dilatation).

CONCLUSIONS

Diuretic renography is highly useful in risk stratification and in the management of newborn infants with hydronephrosis since infants with washout patterns not suggestive of obstruction will rarely develop obstructive hydronephrosis and can initially be followed-up with ultrasonography alone. In indeterminate and obstructive patterns, however, close monitoring that includes diuretic renography is mandatory.

Delayed decrease in differential renal function after successful pyeloplasty in children with unilateral antenatally detected hydronephrosis

AIM

The aim of this study was to evaluate functional outcome of congenital hydronephrotic kidney.

METHODS

The records of consecutive children who underwent pyeloplasty for unilateral prenatally detected ureteropelvic junction obstruction were reviewed. Renal function was assessed renographically before and after surgery. Mean follow-up period was 100 months.

RESULTS

Sufficient pre- and postoperative data were available for 60 children. Differential renal function (DRF) improved in 14 (23%) and decreased in nine (15%) of 60 patients in the early postoperative period. DRF improved in seven (18%) and decreased in 13 (34%) of 38 patients at the end of follow-up. Five of 14 patients with increased DRF at early postoperative scan returned to the preoperative level at the end of follow-up. No patients with decreased DRF at early postoperative scan showed any recovery in DRF and progressive decrease was seen in four of nine children.

CONCLUSIONS

The DRF was not stable in some patients after successful pyeloplasty. In some patients impairment of renal function came to be apparent with time. Improvement of DRF may be a transient phenomenon seen in the early postoperative period. To avoid overestimation of functional recovery, long-term follow-up with delayed renographic evaluation is recommended.

Minimally Invasive Treatment of Ureteropelvic Junction Obstruction: Optimizing Outcomes with Concomitant Cost Reduction

With the seemingly exponential increase in the use of minimally invasive techniques in urology, cost-benefit comparisons will continue to play a major part in establishing services and in improving those that already exist. The management of ureteropelvic junction obstruction is a focus of significant attention. An effective way of optimizing the economy of management is to understand the implications in terms of the success of each mode of treatment. Subsequently, costing models should be developed and applied in large-scale multicenter studies with the aid of health economists. The long-term benefits can then be assessed by also including patient's perceived quality of life. Economic assessment will not be enough to promote cost-effective practices. The take-up of any techniques will always be influenced not only by patient preference and surgeon expertise but also, perhaps ironically, by the way hospitals and surgeons are remunerated. In addition, the impact of the time taken to train a surgeon to carry out laparoscopic dismembered pyeloplasty competently may play a significant role. Until these issues are resolved, definitive recommendation for the treatment of ureteropelvic junction obstruction will continue to be made on an individual basis.

Pattern of renal function deterioration as a predictive factor of unilateral ureteropelvic junction obstruction treatment

OBJECTIVES

To assess the process of renal function deterioration in patients with unilateral ureteropelvic junction (UPJ) obstruction and its impact on their treatment course.

MATERIAL AND METHODS

The files of patients treated for unilateral UPJ obstruction at our department from 1996 to 2003 were retrospectively reviewed. All patients were initially treated conservatively and followed up regularly. Criteria for conversion to surgical treatment were increase in anteroposterial renal pelvis diameter, increase in T(1/2) washout pattern, and drop of relative renal function (RRF) below 40% in diuretic renogram. Patients operated on because of multiple urinary infections, pelvic stones, or solitary kidneys were excluded. Patients were divided into group A, which included those whose treatment was converted from conservative to surgical, and group B in which patients were treated conservatively. All patients operated on underwent dismembered pyeloplasty.

RESULTS

Sixty-four patients with grade three or four hydronephrosis in postnatal ultrasound examination and an obstructive pattern in diuretic renogram were studied. All group A patients (n=47) reached an RRF below 40%; in 41 (87.2%) deterioration of RRF was detected in at least two sequential follow-up studies. In group B patients (n=17), deterioration was also detected in seven (41.1%) patients in two sequential studies (p<0.0005), although the RRF never dropped below 40%. No differences in gender, side of obstruction, or frequency of follow-up were detected between the two groups.

CONCLUSIONS

RRF deterioration and its progression for at least two sequential follow-ups could serve as a predictive factor for surgical treatment.

[Severe primary congenital unilateral hydronephrosis. A review of 98 cases]

INTRODUCTION

Currently, consensus is lacking on the indications for surgery in primary congenital unilateral hydronephrosis.

OBJECTIVES

To analyze the clinical characteristics, treatment and outcome of severe asymptomatic primary congenital unilateral hydronephrosis (grades 3 and 4).

PATIENTS AND METHODS

We performed a retrospective study of 98 neonates with severe primary congenital unilateral hydronephrosis. Diagnostic techniques consisted of ultrasound, renogram, and DMSA scan.

RESULTS

The mean age at diagnosis was 24 days. The mean length of follow-up was 4 years. Forty-eight percent of cases were grade 3 and the remaining cases were grade 4. Fifty-six percent of the patients received conservative treatment. Forty-four percent underwent surgery. Surgical indications consisted of prolonged T1/2, reduced differential renal function and/or very severe hydronephrosis. The mean age at surgery was 5.5 months. In 94 % of the patients who received conservative treatment, hydronephrosis resolved spontaneously. In this group, renal parenchyma and renal function were normal in all patients except two. In 97 % of the patients who received surgical treatment, hydronephrosis was corrected or improved after pyeloplasty. At diagnosis, 19 kidneys had reduced function. In the postsurgical renogram, although T1/2 had markedly improved, 8 kidneys showed reduced function. DMSA performed in 63 patients belonging to both groups, outside the active phase of hydronephrosis, revealed 8 atrophic kidneys, 4 with moderately reduced renal size and function and 4 with scarring and normal renal size and function. During the study period, overall function was maintained in all patients and none developed hypertension.

CONCLUSIONS

Severe congenital unilateral hydronephrosis resolves spontaneously in most patients. Consequently, clinicians increasingly adopt a conservative approach. The available diagnostic techniques cannot identify patients who will benefit from pyeloplasty. In general, accepted surgical indications are an increase in hydronephrosis and/or worsening of renal function. In our series, 15 % of the patients with hydronephrosis had an irreversible lesion of variable severity, which in some patients seemed to have developed during embryogenesis. Kidneys at risk of presenting a lesion were those that had grade 4 hydronephrosis.

Postnatal unilateral pelviureteral junction obstruction: impact of pyeloplasty and conservative management on renal function

OBJECTIVES

To study the effect of pyeloplasty and conservative management on renal function in children with pelviureteral junction obstruction.

METHODS

This prospective study included 65 children postnatally diagnosed with unilateral pelviureteral junction obstruction. On the basis of the patients' symptoms and technetium-99m diethylenetriamine pentaacetic acid renal isotope scan findings, symptomatic patients or those with split function of the corresponding kidney of 40% or less were assigned to group 1 (n = 35) and underwent pyeloplasty. Asymptomatic patients with split function greater than 40% (group 2, n = 30) were treated conservatively. Patients who showed deterioration of renal function underwent pyeloplasty. The effect of both lines of treatment on renal function was evaluated.

RESULTS

After pyeloplasty, group 1 had improvement in the glomerular filtration rate (GFR) in 30 (85.7%), stabilization in 2 (5.7%), and deterioration in 3 (8.6%) patients. In group 1, the comparison between the mean value of the baseline GFR (17.1 +/- 7.7 mL/min) and its mean value at follow-up (28 +/- 6.3 mL/min) showed an increase of statistical significance (P <0.01). In the group 2 patients, conservative treatment resulted in improvement in the GFR in 12 (40%), stabilization in 3 (10%), and deterioration in 15 (50%) patients. In group 2, no significant difference was found between the mean baseline GFR (29.8 +/- 9.8 mL/min) and its mean value at follow-up (31.2 +/- 5.6 mL/min).

CONCLUSIONS

In patients with postnatal pelviureteral junction obstruction, early pyeloplasty is recommended if the corresponding GFR is 40% or less. Conservative management in patients with better function resulted in deterioration of renal function in 50%. Should this policy of treatment be chosen, meticulous follow-up is mandatory.

Congenital unilateral hydronephrosis: a review of the impact of diuretic renography on clinical treatment

PURPOSE

The natural history of and optimal treatment for asymptomatic congenital hydronephrosis is unknown, mainly because most published series are nonrandomized or retrospective with nonstandardized followup regimens. In this survey we provide an overview of the different strategies used for the treatment of congenital unilateral hydronephrosis.

MATERIALS AND METHODS

A comprehensive literature review of clinical studies of asymptomatic congenital unilateral hydronephrosis is presented.

RESULTS

Different criteria for surgical intervention and different followup regimens have been used. Identification of the population at risk has been attempted but results are ambiguous. Surgery is done in approximately 25% of cases when using deteriorating differential function, symptoms and/or increasing hydronephrosis as criteria for operation. A nonstandardized renographic assessment does not compromise evaluation of the ideal followup but it may compromise the functional outcome.

CONCLUSIONS

More studies of kidneys with decreased function, severe hydronephrosis or poor drainage investigated with a standardized protocol are needed to clarify the natural history and establish optimal guidelines for treatment and followup.

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.

Differential renal function in the prediction of recovery in adult obstructed kidneys after pyeloplasty

AIM

Pyeloplasty is a widely accepted method for the treatment of ureteropelvic junction obstruction (UPJO). Surgery has long been thought to affect postoperative renal function. However, controversies still exist on the functional studies that can be used to indicate which renal units will benefit from surgery. In this study, the correlation between differential renal function (DRF) and other preoperative parameters was examined to determine which parameter more accurately predicts recovery of renal function in adult obstructed kidneys.

MATERIALS & METHODS

In this study, the authors evaluated 32 patients with UPJO. In all patients, standart diuretic Tc-99m DTPA renal scans were performed preoperatively and 6 months after surgery. Patients were divided into two groups according to the preoperative DRF (> or = 30%, n = 22, group I and < 30%, n = 10, group II). Second type classification was made according to the postoperative DRF improvement as improved (group A, n = 13) and not improved (group B, n = 19). These groups were then compared regard to variables which were defined as symptoms, age at operation and ultrasonographic findings. We also evalulated whether preoperative parenchymal function is important to predict improvement in drainage half-time (T1/2).

RESULTS

While preoperative drainage half-time was 39.6 +/- 15.9 minutes, postoperative half-time decreased to 16.9 +/- 6.8 minutes (p < 0.001). The mean DRF did not improved significantly after surgery compared with preoperative values (32.03 +/- 9.42% versus 36.16 +/- 9.60%). When comparing the patients with preoperative DRF > or = 30% (group I, DRF 38 +/- 0.8%) to those who had an initial DRF below 30% (group II, DRF 22.8 +/- 5.2%), postoperative DRF was 41.22 +/- 5.72 in group I and 25.00 +/- 6.22 in group II. The difference was significant (p < 0.01). The patients in group I and II showed improvement in 50% and 20%, respectively. Age, clinical presentation and ultrasonographic findings did not affect functional outcome after pyeloplasty. We could not find any correlation between preoperative DRF and the degree of improvement in T1/2.

CONCLUSION

Renal function improves after pyeloplasty with regard to the initial level of split renal function in adult obstructed kidneys. Improvement may not be observed especially in patients with DRF less than 30%.

Increased nephron volume is not a cause of supranormal renographic differential renal function in patients with ureteropelvic junction obstruction

PURPOSE

Increasing clinical importance is being placed on the role of differential renal function (DRF) in the management of congenital ureteropelvic junction obstruction. Supranormal DRF of the hydronephrotic kidney on renal scan is a puzzling phenomenon and is hypothesized to be due to an increase in single nephron filtration or nephron volume without sound evidence. We studied the histopathological changes of hydronephrotic kidneys to determine whether glomerular hypertrophy underlies supranormal DRF.

MATERIALS AND METHODS

We retrospectively evaluated the records of 3 females and 32 males with unilateral congenital hydronephrosis who underwent pyeloplasty. Mean patient age at operation was 12.6 months (range 0.1 to 144). Needle biopsies from 3 different sites at the lower pole of the kidney were performed during surgery. To evaluate the presence of glomerular hypertrophy, the maximal planar area of glomeruli was measured under light microscopy using an image analyzer. Tissue samples obtained from kidneys without a history of urinary tract disease at autopsy were used as controls. The mean glomerular areas of the patient and control groups were evaluated according to DRF and age.

RESULTS

The mean glomerular area values of the patient group were smaller than those of the control group, except for 4 patients. The glomerular areas of the hydronephrotic kidneys with supranormal DRF were not significantly different from those of the control group. Instead, the probability of larger renal glomeruli increased with decreasing DRF (p = 0.1155).

CONCLUSIONS

Increased nephron volume can be discounted as a cause of supranormal DRF.

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.

Dynamic gadolinium-enhanced magnetic resonance urography for assessing drainage in dilated pelvicalyceal systems with moderate renal function: preliminary results and comparison with diuresis renography

OBJECTIVE

To evaluate the use of dynamic gadolinium diethylenetriaminepenta-acetic acid (DTPA)-enhanced magnetic resonance urography (Gd-MRU) for assessing kidneys with markedly dilated pelvicalyceal systems and impaired function.

PATIENTS AND METHODS

Eight children (mean age 30 months, sd 25) were assessed, diagnosed as having gross unilateral hydronephrosis with a mean (sd) anteroposterior renal pelvic diameter of 36 (7) mm and reduced (30-40%) renal function. Dynamic Gd-MRU was performed after the patients were pre-loaded with intravenous fluid and diuretics, and comprised a dynamic T1-weighted sequence after Gd-DTPA (0.1 mmol/kg body weight) was administered, with a time-intensity curve of each kidney produced. Drainage was diagnosed by a clearly declining time-intensity curve and direct visualization of contrast medium within the ureter in several frames. High-grade or complete obstruction was diagnosed when drainage of contrast medium could not be detected. Gd-MRU results were compared with diuresis radionuclide (mercapto-acetyltriglycine, MAG3) renography within the same week. Unobstructive units detected by Gd-MRU were treated conservatively with a close follow-up by ultrasonography and radionuclide studies.

RESULTS

Diuresis MAG3 renography showed drainage in three dilated units and poor washout in five; in contrast, Gd-MRU showed drainage in seven dilated systems (three showed poor washout by MAG3), and obstruction in the remaining case. The unobstructed units detected by MRU under conservative treatment thus showed no further deterioration of renal function or progressive hydronephrosis in the subsequent follow-up (mean 18 months, range 15-23).

CONCLUSION

These preliminary results suggest that dynamic Gd-MRU is a useful noninvasive imaging method in distinguishing obstructive from unobstructive dilated systems, particularly in patients with hydronephrosis and reduced renal function.

Ureteropelvic junction obstruction in children: two variants of the same congenital anomaly?

OBJECTIVE

To compare the characteristics of prenatally and postnatally diagnosed ureteropelvic junction obstruction (UPJO) in children.

PATIENTS AND METHODS

We reviewed the records of 74 children who underwent pyeloplasty or nephrectomy for UPJO between 1995 and 2000. The patients were divided into 2 groups: prenatally and postnatally diagnosed UPJO. In each group, we compared age at surgery, gender, affected side, anteroposterior diameter (APD) of the renal pelvis, surgical findings, and renal function as determined by creatinine clearance.

RESULTS

Of the 74 children, 44 (59.4%) had a prenatal diagnosis of UPJO and 30 (40.6%) had a postnatal diagnosis despite the fact that all had had a fetal ultrasonography. Median age at the time of surgery was 6.3 years (4 months to 16 years) for children with postnatal UPJO and 3.6 months (1 month to 4 years) for the prenatal group. Forty-three percent of the children in the postnatal group and 25% in the prenatal group were females. Clinical manifestations in children with postnatal UPJO included abdominal pain in 13 (43%) patients, pyelonephritis in 7 (23%), urinary tract infection in 5 (16.6%), and occasional findings upon ultrasound in 5 (16.6%). Excretory urography suggested obstruction in most children. The surgical findings included ureteral kinks due to adhesions in 93.3% of postnatally diagnosed UPJO cases and in 27.3% of prenatal cases (p < 0.01). A reduction in mean creatinine clearance of hydronephrotic kidneys was observed for both groups when compared to reference values for the respective ages, but this difference was not statistically significant.

CONCLUSIONS

Postnatally diagnosed UPJO may be considered, at least in part, an entity different from prenatally detected obstruction due to its peculiar characteristics, i.e., postnatal UPJO more frequently affects females, manifests later in life with urinary infection or abdominal pain, and is frequently associated with ureteral kinking.

A prospective study comparing ultrasound, nuclear scintigraphy and dynamic contrast enhanced magnetic resonance imaging in the evaluation of hydronephrosis

PURPOSE

A combination of nuclear medicine, ultrasound and voiding cystourethrography is typically used to investigate hydronephrosis in children. A major problem is the lack of an accepted gold standard to assess obstruction. In some cases the anatomy is unclear. By combining anatomical and functional information in one study, magnetic resonance imaging (MRI) has the potential of providing superior information regarding hydronephrosis. We evaluate the role of dynamic enhanced MRI and compare it to other imaging modalities in the investigation of pediatric hydronephrosis.

MATERIALS AND METHODS

One hundred dynamic contrast enhanced MRIs were performed in 96 children (35 girls and 61 boys, mean age 4 years [range 1 month to 17 years]). The information from the various imaging modalities was compared.

RESULTS

The MRI protocol was acceptable to all families and was performed without complications in all patients. The morphological imaging with MRI was superior to conventional imaging in all cases. The split renal function as calculated by nuclear and MRI scans was compared in 71 cases, and the correlation coefficient was r2 = 0.93. The combination of ultrasound and a nuclear medicine study correlated with the final diagnosis of the MRI in 50 of 64 studies (78%). Of the 14 studies that differed 8 were obstructed on MRI but not on the nuclear studies, and 5 were not obstructed on MRI but were obstructed on the nuclear studies. One patient believed to have ureteropelvic junction obstruction on nuclear medicine scan had ureterovesical junction obstruction on MRI. The final diagnoses by MRI were ureteropelvic junction obstruction in 26 children, primary ureterovesical junction obstruction in 14, dilated but not obstructed systems in 35, duplex systems in 13, multicystic dysplastic kidneys in 5, unilateral small scarred kidney in 1, acute pyelonephritis in 2, renal mass in 1, bilateral polycystic kidneys in 1 and normal study in 9. Sedation was administered safely without any complications.

CONCLUSIONS

Dynamic contrast enhanced MRI provides equivalent information about renal function but superior information regarding morphology in a single study without ionizing radiation. MRI has the potential to replace the currently used combination of other imaging modalities in the investigation of hydronephrosis in children.

Unilateral ureteropelvic junction obstruction in children: long-term followup after unilateral pyeloplasty

PURPOSE

The benefit of surgery on renal function in unilateral ureteropelvic junction stenosis (UPJS) is still debated. We evaluated renal function outcome after unilateral pyeloplasty in 53 children.

MATERIALS AND METHODS

We retrospectively reviewed 123I-hippuran renography performed at diagnosis and 5 to 15 years (mean +/- SD 7 +/- 3 years) after successful pyeloplasty. UPJS was prenatally detected in 26 children because of urinary tract infection in 17 and miscellaneous reasons in 10. Relative function (RF) and absolute function were measured on background corrected renograms. Absolute function of the affected and contralateral kidneys was determined by an accumulation index (AI), representing the percent injected dose extracted by each kidney 30 to 90 seconds after the heart peak.

RESULTS

Preoperatively 33 of the 53 UPJS kidneys had a decreased AI but only 8 had a RF of less than 40%, which was improved in 7 at followup. In addition, the AI improved in 29 kidneys, of which 19 (36%) normalized. Of the UPJS kidneys 14 had an initially decreased AI that remained abnormal at followup. In these kidneys preoperative RF was less than 40% in all. At followup RF was greater than 40% in 4 children, in whom the AI of the UPJS kidney did not improve but the AI of the contralateral one decreased from supranormal to normal. Seven contralateral kidneys had a supranormal AI, whereas the AI remained normal in 3, of which the RF in the UPJS kidney remained at less than 40%. The AI and RF were normal in 20 UPJS kidneys and remained normal.

CONCLUSIONS

When normal, the AI and RF reflected renal function outcome similarly. The AI added relevant information in UPJS kidneys with impaired function, showing compensation of the contralateral kidney.

Diuretic renogram clearance half-times in the diagnosis of obstructive uropathy: effect of age and previous surgery

Diuretic renography with radiotracers has been used successfully to diagnose obstruction in patients with hydronephrosis. Controversy persists with regard to the best approach for the interpretation of renogram curves: visual analysis or a quantitative index, i.e. the clearance half-time. The latter is often reported to be in the intermediate or non-diagnostic range. It is important to measure the incidence of equivocal half-times in various subsets of patients with hydronephrosis in order to determine in which settings the measurement of this index may be clinically useful. We performed a retrospective study of diuretic renograms performed at our institution between 1997 and 2000 for the evaluation of suspected uretero-pelvic junction (UPJ) obstruction. Vigorous intravenous hydration, exceeding current guidelines, was employed in these patients. Three hundred and seventy-seven renogram curves in 205 patients were analysed. Patients were divided into three groups: >1 year of age; <or=1 year of age; and those who had previously undergone surgical correction of obstruction regardless of age. Patients with reflux or anatomical abnormalities of the urinary tract, those with chronic renal failure, those with bilateral normal clearances before furosemide administration and those with unilateral normal clearances before furosemide administration with contralateral poor renal function were excluded. In the remaining 119 patients, 205 clearance half-times were classified as normal before furosemide, normal after furosemide (half-time, <10 min), prolonged (half-time, >20 min) or intermediate (half-time, 10-20 min). In patients >1 year of age, 37% of 101 renograms showed normal half-times before furosemide, 20% showed normal half-times after furosemide, 44% showed prolonged half-times and none (0%) showed an intermediate half-time. In patients </=1 year of age, there was a statistically significantly different distribution, with 48% of 64 renograms showing normal washout before furosemide, 16% showing normal clearance after furosemide, 19% showing abnormal half-times and 17% showing intermediate half-times. In 33 renograms from patients who had undergone corrective surgery, 49% had normal half-times, 24% had prolonged half-times and 27% had intermediate half-times. It can be concluded that, when using the selection criteria, hydration, acquisition and processing protocols and half-time definition employed in this study, the addition of a clearance measurement in patients older than 1 year with suspected UPJ disease enhances patient classification and may improve the diagnostic confidence. There was a significantly higher incidence of intermediate half-times in patients with native disease aged <1 year than in those >1 year. Caution is advised when interpreting this finding in this age group. The measurement of washout was less useful in patients who had undergone a corrective procedure, because of the high rate of 'indeterminate' and 'abnormal' values in spite of successful surgery. Vigorous intravenous hydration, exceeding current standards, may have contributed to the lower incidence of intermediate half-times than reported previously.

Unilateral urinary flow impairment at the pelviureteral junction: outcome of renal function with respect to therapeutic strategy

OBJECTIVES

To evaluate the renal function outcome in children with unilateral hydronephrosis and urinary flow impairment at the pelviureteral junction with respect to the therapeutic strategy.

METHODS

We retrospectively selected 45 children with iodine-123-hippuran renography performed at diagnosis and after 3 or more years of follow-up. All children had bilateral nonobstructive pattern findings on diuretic renography at follow-up. Eleven children were treated conservatively, and 34 underwent unilateral pyeloplasty. Split and individual renal function, measured by an accumulation index, was computed from background-corrected renograms for the affected and contralateral kidneys at diagnosis and the follow-up examination.

RESULTS

Of 11 children treated conservatively, 9 had normal bilateral function at diagnosis, all had reached normal function at follow-up. Of the 34 operated kidneys, 12 (38%) had initially normal function that remained normal at the follow-up examination, and 22 had impaired function that had normalized at the follow-up examination in 15 (68%). The function of the contralateral kidneys was increased in 5 of 8 children with persistently abnormal affected kidneys. Pyeloplasty was performed in 23 children (68%) and 11 children (32%) younger and older than 1 year, respectively. The function of the affected kidneys increased in both groups, but normalization occurred only in the younger children.

CONCLUSIONS

Of the children selected for conservative treatment, 82% had normal bilateral renal function at diagnosis that was normal in all at the follow-up examination. Of the children treated surgically, 65% had initially impaired function of the affected kidney that improved in 87% after pyeloplasty. Normalization of function was observed only in children who were younger than 1 year old at surgery. Persistently low function of the affected kidney was compensated for by the contralateral one regardless of the age at surgery.