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

Renal cortical transit time as a predictor for pyeloplasty in pediatric patients with unilateral hydronephrosis

Majority of patients with unilateral hydronephrosis (HN) detected on ultrasound do not require pyeloplasty. The measurement of the cortical transit time (CTT) has been demonstrated by several authors to predict the need for patients who may require pyeloplasty. The study aimed to assess if CTT would have predicted a drop in differential renal function (DRF) in patients with unilateral HN on the affected side and to assess whether CTT would differ on the first renogram between those patients who had a pyeloplasty and those who did not have a pyeloplasty. Sixty-eight patients with at least two renograms with unilateral HN with a normal contralateral kidney were observed retrospectively. The CTT was recorded for each kidney. Renograms were processed three times to measure the DRF. The mean of the three DRF measurements was used for analysis. The mean CTT of the left and right hydronephrotic kidneys was 6.0 min and 6.7 min, respectively. The relationship between CTT and DRF as well as CTT and anterior posterior diameter in the first renogram of those patients who did not have a pyeloplasty was statistically significant (P < 0.05). In the 20 patients who had a pyeloplasty, there was a drop of more than 10% in the DRF of three patients. No significant difference was found in CTT or DRF when comparing the group who had surgery against the group who did not have surgery. The current study was unable to demonstrate in our series of patients that CTT can predict a drop in DRF in those patients who would require pyeloplasty.

Cortical transit time: understanding utility and pitfalls in children with pelviureteric junction obstruction

INTRODUCTION

Delayed cortical transit time (CTT) has been recently studied and proposed as a parameter that can predict the need for surgery in children with pelviureteric junction obstruction (PUJO).

AIM

The aim of this study was to study the change in CTT, after surgery, in children with PUJO and to correlate CTT with intrapelvic pressure of the kidney.

MATERIAL AND METHODS

A prospective study was performed, and all children who underwent pyeloplasty from January 2016 to December 2017 were included. Pre-operative and postoperative renal ultrasonography and Technetium-99m mercaptoacetyltriglycerine Tc-MAG3 renal scintigraphy were performed. Cortical transit time was measured by a visual method by two different observers. The renal intrapelvic pressure of the kidney was also measured during surgery after giving a diuretic to replicate the diuresis induced during the renal scan. The correlation was studied between the pre-operative CTT and intrapelvic pressures and between the pre-operative CTT and the renal function of the affected kidney.

RESULTS

Thirty-one children were included in the study. The median age of children who underwent surgery was 50 months (2-168). In 71% of patients, the CTT was prolonged before surgery, whereas only 22.5% had delayed CTT after surgery. The mean CTT before surgery was 226.1 ± 74.8 s and decreased to 165.4 ± 55.9 s after surgery (p= <0.001). The mean intrapelvic pressure was 21 ± 7.5 cm H₂O. There was no correlation noted between the intrapelvic pressure and the CTT. A significant negative correlation was noted between the CTT and the different renal function of the kidney.

DISCUSSION

This is the first prospective study that studies the changes in CTT after surgery. Only retrospective studies had been conducted to date which concluded that CTT was delayed in most of the patients who had been operated. It has been proposed that the prolonged CTT is due to raised pressure in the kidney secondary to obstruction. This study did not find any correlation between the pressure and CTT. The significant negative correlation between CTT and renal function also emphasizes the need to take the renal function into consideration before interpreting and using the absolute value of CTT for guiding treatment.

CONCLUSION

Cortical transit time assessment by the visual method is a useful parameter in the management of children with PUJO. There is a significant improvement in CTT after surgery.

Diuretic Enhanced Ultrasonography in the Diagnosis of Pyeloureteral Obstruction

Background and Objectives: To determine the value of diuretic ultrasonography for the diagnosis of obstructive hydronephrosis. Materials and Methods: Diuretic enhanced ultrasonography was used routinely as a part of examination of patients with hydronephrosis in our Department. There were 72 patients (42 males, 30 females; aged 2 months to 17 years; median age 7.07 years) with a sonoscopic diagnosis of hydronephrosis included from January 2006 until October 2011. The anteroposterior diameter (AD) of renal pelvis was measured sonoscopically before and at sixty minutes after furosemide injection. A weight-adjusted dose of 1 mg/kg of furosemide was administered intravenously. Results: Patients were operated on if pyeloureteral obstruction was suspected because of low or deteriorating differential renal function, increasing hydronephrosis or symptoms thereof. Hydronephrosis was unilateral in 61 (84.7%) and bilateral in 11 (15.3%) patients. The median AD of pelvis before furosemide injection was 22 mm in operated and 17 mm in non-operated patients (p = 0.005). Sixty minutes after furosemide injection, the AD of pelvis in operated patients was 35.5 mm and 25.8 mm in non-operated—25.8 mm (p < 0.001). Logistic regression model demonstrated that significant factors for surgery were: AD 60 min after furosemide infection and ultrasonographic parenchymal sclerosis. Conclusion: Ultrasound measurement of the AD of renal pelvis 1 h after the injection of furosemide used as an additional investigation can help in predicting obstructive hydronephrosis.

99mTc-DTPA Diuretic Renography with 3 hours late output fraction in the evaluation of hydronephrosis in children

Objective:

Dynamic renal scintigraphy complemented by late gravity assisted postvoid images to 60 minutes is a frequently used diagnostic test in the evaluation of hydrone- phrosis. The objective of this study is to evaluate the effectiveness in acquiring images at 180 minutes to calculate the late output fraction (LOF) of ^99mTc-DTPA in the diagno- sis of ureteropelvic junction obstruction (UPJO).

Materials and Methods:

A retrospective study of 177 patients (196 renal units) of sus- pected cases of clinical UPJO was conducted. The patients were submitted to at least two dynamic renal scintigraphies of ^99mTc-DTPA, with the addition of furosemide (F0), with a mean age of 4.3±3.8 years for the first study, and a follow-up of 2.7±2.5 years.

Results:

For diagnosis based on renal curves, a 100% sensitivity, 82.2% specificity, positive predictive value (PPV) of 10.4% and negative predictive value (NPV) of 100% were estimated. For diagnosis based on LOF, a 100% sensitivity, 96.3% specificity, PPV of 35.7% and NPV of 100% were estimated.

Conclusion:

A LOF <10% is indicative of UPJO, and a LOF ≥15% is indicative of no UPJO. The data demonstrate that LOF presents equivalent sensitivity and NPV, and higher specificity and PPV in comparison to diagnosis based on renal curves, and is useful in the evaluation and follow-up of suspected cases of UPJO.

Primary non-surgical management of unilateral ureteropelvic junction obstruction in children: a systematic review

Ureteropelvic junction obstruction (UPJO) is the most common obstructive uropathy and its optimal management remains controversial. However, there is a current trend towards non-surgical management. We aimed to determine the effects of the non-surgical management in children with unilateral UPJO. For a systematic review, we searched MEDLINE, EMBASE, CENTRAL, clinical trials registries, and selected conference proceedings for eligible studies. Any type of study reporting the outcomes renal function, secondary surgical intervention, drainage pattern or hydronephrosis of non-surgical management in children with unilateral UPJO was included. Data from 20 studies were extracted and evaluated by two independent authors. The pooled prevalence was 21% for split renal function deterioration, 27.9% for secondary surgical intervention, 3.2% for progressive hydronephrosis, and 82.2% for improved drainage pattern. Not all patients with surgical intervention regained split renal function from enrolment. Renal imaging methods did not strongly correlate with each other. Many studies had to be excluded because of a lack of detection of an obstruction or mixed populations with bilateral UPJO or other uropathies. The variable definitions of UPJO, different criteria for surgical intervention, incongruity of management protocols, and the imprecise reporting of outcomes were limiting factors in the comparability of the results, leading to heterogeneity in meta-analyses. Although the available evidence cannot recommend or refute the current non-surgical management, the systematic review clarifies aspects of the ongoing controversy by providing realistic estimates for non-surgical management in children with unilateral UPJO. Additionally, it reveals unclear potential risks, particularly for long-term outcomes, which were rarely reported.

Revised guidelines on management of antenatal hydronephrosis

Widespread antenatal screening has resulted in increased detection of anomalies of the kidneys and urinary tract. The present guidelines update the recommendations published in 2000. Antenatal hydronephrosis (ANH) is transient and resolves by the third trimester in almost one-half cases. The presence of oligohydramnios and additional renal or extrarenal anomalies suggests significant pathology. All patients with ANH should undergo postnatal ultrasonography; the intensity of subsequent evaluation depends on anteroposterior diameter (APD) of the renal pelvis and/or Society for Fetal Urology (SFU) grading. Patients with postnatal APD exceeding 10 mm and/or SFU grade 3-4 should be screened for upper or lower urinary tract obstruction and vesicoureteric reflux (VUR). Infants with VUR should receive antibiotic prophylaxis through the first year of life, and their parents counseled regarding the risk of urinary tract infections. The management of patients with pelviureteric junction or vesicoureteric junction obstruction depends on clinical features and results of sequential ultrasonography and radionuclide renography. Surgery is considered in patients with increasing renal pelvic APD and/or an obstructed renogram with differential renal function <35-40% or its subsequent decline. Further studies are necessary to clarify the role of prenatal intervention, frequency of follow-up investigations and indications for surgery in these patients.

Fetal counselling for surgical conditions

Foetal counselling is best achieved by a multidisciplinary team that can favourably influence the perinatal management of prenatally diagnosed anomalies and provide this information to prospective parents. Prenatal diagnosis has remarkably improved our understanding of surgically correctable congenital malformations. It has allowed us to influence the delivery of the baby, offer prenatal surgical management and discuss the options of termination of pregnancy for seriously handicapping or lethal conditions. Antenatal diagnosis has also defined an in utero mortality for some lesions such as diaphragmatic hernia and sacrococcygeal teratoma so that true outcomes can be measured. The limitation of in-utero diagnosis cannot be ignored. The aim of prenatal counselling is to provide information to prospective parents on foetal outcomes, possible interventions, appropriate setting, time and route of delivery and expected postnatal outcomes, immediate and long term.

Antenatal detection of pelviureteric junction stenosis: main controversies

Although renography has been used for half a century to evaluate the function of the infant kidney, there are still important disagreements among the specialists involved in this particular pathology. Each department of nuclear medicine has his own way to acquire and process a renogram; to interpret the obtained images, curves, and quantitative parameters; and to make recommendations for the referring physician. The urologist has his or her part of responsibilities because the decision for operating or not operating varies from one center to another and is generally determined by a series of unproven assumptions. The aim of the present work is to focus on the main controversies involving both the nuclear medicine physician and the urologist. Concerning the technique of renography. The bladder catheter, systematically recommended in different centers, can best be replaced in most of the cases by a much less-invasive procedure, namely the acquisition and processing of late postmicturition (PM) posterect images. The change of patient's position contributes strongly to the renal washout. Intravenous hydration is used to standardize the level of hydration. However, the patients, in most of the cases, are in good health, and adequate oral hydration is sufficient. Even if hydration was not ideal when the procedure began, the administration of furosemide and the late PM images will result in a very good drainage of a normal kidney. Any renal tracer with high extraction rate is adequate, but diethylene triamine pentaacetic acid ((99m)Tc-DTPA) does not allow a precise estimation of differential function in children younger than 6 months. The moment of furosemide injection (F0, F+20, F-15) does not influence the quality of the final renal washout, and the F0 procedure is recommended in cases of known hydronephrosis because it shortens the time of acquisition on the gamma camera and allows the simultaneous injection of both the tracer and the diuretic. Background correction remains controversial among nuclear medicine physicians. Including in the background area some liver and spleen activity, which are responsible for an important part of the extrarenal activity within the renal area, will improve the quality of the renogram curve, suppressing almost completely the initial vascular phase. The supporters of the Rutland-Patlak (R-P) fit for calculating differential function state that the vascular component is eliminated better than with use of the classical integral method. However, this method is based on a slope, with counting statistics being rather poor in infants with immature function. In most of the cases, the integral method will provide robust results. Determination of the same differential function by the use of both methods increases the level of confidence of the final results. It is generally admitted that the first renogram in children with antenatally detected hydronephrosis should be performed at approximately 1 month of age. However, there is a tendency to start earlier, and even in the first days of life, in case of huge hydronephrosis. The renogram should be repeated in case of significant hydronephrosis, significant increase of dilation, poor response to furosemide, or low initial differential function. Moderate dilation associated with normal differential function can probably be monitored by ultrasound alone. T(½) of the diuretic curve is an empiric parameter that does not take into account the bladder emptying and the change of patient's position. Output efficiency (OE) and normalized residual activity (NORA), measured on the late PM and posterect images, represent physiological parameters not dependent on the input function of the considered kidney and can be used whatever the moment of furosemide injection. There is presently no way to quantitatively measure cortical transit in antenatally detected pelviureteric junction syndrome; all methods are limited by the slight kidney motion related to respiratory movements and by the almost-complete superimposition between cortical area and collecting system. The best approach probably is a visual estimation. Concerning the position of the urologist. The main controversy is related to the definition of obstruction and the indication for surgery. Neither the degree of hydronephrosis nor the impairment of differential function and/or the quality of the response to furosemide can define which kidney is in danger of further deterioration. Alternatively, these parameters are unable to predict for which kidneys an improvement of differential function can be expected because of a pyeloplasty. It has not been excluded, according to recent published work, that cortical transit could be a better predictive factor of the risk of a conservative attitude or the benefits of a surgical procedure, but this procedure has still to be confirmed.

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.

Diuretic renography in hydronephrosis: renal tissue tracer transit predicts functional course and thereby need for surgery

PURPOSE

The recognition of those hydronephrotic kidneys which require therapy to preserve renal function remains difficult. We retrospectively compared the 'tissue tracer transit' (TTT) of (99m)Tc-mercaptoacetyltriglycine ((99m)Tc-MAG(3)) with 'response to furosemide stimulation' (RFS) and with 'single kidney function < 40%' (SKF < 40%) to predict functional course and thereby need for surgery.

METHODS

Fifty patients with suspected unilateral obstruction and normal contralateral kidney had 115 paired (baseline/follow-up) (99m)Tc-MAG(3) scintirenographies. Three predictions of the functional development were derived from each baseline examination: the first based on TTT (visually assessed), the second on RFS and the third on SKF < 40%. Each prediction also considered whether the patient had surgery. Possible predictions were 'better', 'worse' or 'stable' function. A comparison of SKF at baseline and follow-up verified the predictions.

RESULTS

The frequency of correct predictions for functional improvement following surgery was 8 of 10 kidneys with delayed TTT, 9 of 22 kidneys with obstructive RFS and 9 of 21 kidneys with SKF < 40%; for functional deterioration without surgery it was 2 of 3 kidneys with delayed TTT, 3 of 20 kidneys with obstructive RFS and 3 of 23 kidneys with SKF < 40%. Without surgery 67 of 70 kidneys with timely TTT maintained function. Without surgery 0 of 9 kidneys with timely TTT but obstructive RFS and only 1 of 16 kidneys with timely TTT but SKF < 40% lost function.

CONCLUSION

Delayed TTT appears to identify the need for therapy to preserve function of hydronephrotic kidneys, while timely TTT may exclude risk even in the presence of an obstructive RFS or SKF < 40%.

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.

Antenatally detected hydronephrosis

The strategy of management of children with hydronephrosis has considerably changed as a result of the development of ultrasound techniques, allowing a prenatal detection. Hydronephrosis is defined as a dilation of the renal collecting system, and several entirely different clinical entities can be considered this general heading, whereas early detection may have a different impact depending on the entity considered. The present work aims to describe a certain number of these clinical entities, to discuss the strategic options of management that are proposed, and to evaluate the role of medical imaging, in particular the radionuclide approach. Congenital ureteropelvic junction anomaly, vesicoureteral reflux, posterior urethral valves, and duplex kidney will be successively considered. Multicystic dysplastic kidney disease, although not classified as hydronephrosis, will be mentioned because it may be mistaken for hydronephrosis.

[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.

The management of renal conditions in the perinatal period

Most urogenital abnormalities are now diagnosed antenatally on high resolution ultrasound scans. This has enabled recognition of those that are not compatible with survival and these are managed with termination of pregnancy. Renal anomalies that require surgical intervention continue to pose challenges. Conditions such as multicystic dysplastic kidney can be easily recognised and managed based on the experience gained with long-term studies of its natural history. Polycystic kidney on the other hand while not posing a diagnostic problem remains beyond the reach of therapeutic intervention and postnatal supportive measures are the only available means of dealing with this entity at present. The major difficulty is with the management of antenatally diagnosed pelvicalyceal dilatation. The goal of intervention is to preserve renal function when dilatation is the consequence of obstruction. Unfortunately, by the time ultrasound evidence of significant obstruction is apparent renal damage is already established. Fetal intervention should be considered in those cases where severe oligohydramnios is associated with hydronephrosis, especially in the presence of a solitary kidney or in bilateral disease. Postnatally, all neonates with renal tract dilatation should be managed according to a protocol which mandates serial measurements of renal pelvis diameter and correlates this with data from radionuclide scans. This will enable recognition of kidneys that are at risk of losing function while at the same time avoiding unnecessary surgical intervention in those which remain dilated but are functionally stable.

Pediatric applications of renal nuclear medicine

This review should be regarded as an opinion based on personal experience, clinical and experimental studies, and many discussions with colleagues. It covers the main radionuclide procedures for nephro-urological diseases in children. Glomerular filtration rate can be accurately determined using simplified 2- or 1-blood sample plasma clearance methods. Minor controversies related to the technical aspects of these methods concern principally some correction factors, the quality control, and the normal values in children. However, the main problem is the reluctance of the clinician to apply these methods, despite the accuracy and precision that are higher than with the traditional chemical methods. Interesting indications are early detection of renal impairment, hyperfiltration status, and monitoring of nephrotoxic drugs. Cortical scintigraphy is accepted as a highly sensitive technique for the detection of regional lesions. It accurately reflects the histological changes, and the interobserver reproducibility in reporting is high. Potential technical pitfalls should be recognized, such as the normal variants and the difficulty in differentiating acute lesions from permanent ones or acquired lesions from congenital ones. Although dimercaptosuccinic acid scintigraphy seems to play a minor role in the traditional approach to urinary tract infection, recent studies suggest that this examination might influence the treatment of the acute phase, the indication for chemoprophylaxis and micturating cystography, and the duration of follow-up. New technical developments have been applied recently to the renogram: tracers more appropriate to the young child, early injection of furosemide, late postmicturition and gravity-assisted images and, finally, more objective parameters of renal drainage. Pitfalls mainly are related to the interpretation of drainage on images and curves. Dilated uropathies represent the main indication of the renogram, but the impact of this technique on the management of the child is, in a great number of cases, still a matter of intense controversy. Direct and indirect radionuclide cystography are interesting alternatives to the radiograph technique and should be integrated into the process of diagnosis and follow-up of vesicoureteral reflux.

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.

Antenatally detected, unilateral dilatation of the renal pelvis: a critical review. 2. postnatal non-operative treatment--long-term hazards, urgent research

BACKGROUND

Even after two decades, there is still much discussion about the postnatal treatment of antenatally detected, isolated pelvic dilatation (consistent with pyelo-ureteral junction obstruction). A recent review concluded that non-operative expectancy seemed safe - even after 17 years in certain cases. However, the final outcome, i.e. when these children have reached old age, is remote.

OBJECTIVE

This review takes stock of conceivable long-term hazards and evaluates prognosticating tools, and offers a basis for protocols for future randomized controlled trials. Long-term hazards: Symptoms in this context are generally considered ominous. In the antenatally detected cases, i.e. primarily asymptomatic, symptoms have been reported but they were not necessarily combined with renal damage. Hydronephroses, so mild, that they are written off, may deteriorate later on (indeed insidiously), although probably seldom. Urgent research: A predictor of outcome is eagerly pursued but hard to obtain, due to the difficulty in defining true obstruction in compliant systems such as the urinary one. Ordinary diagnostics offer no help, but there are promising innovations: constant pressure/flow assessment (flow necessary to keep a preset intrapelvic pressure), NAG/creatinine in pelvic urine, and TGFbeta-1 in voided urine. Renal microstructure, sometimes severely damaged early (which disagrees with the good results with expectancies) could possibly herald future deterioration.

CONCLUSION

Adverse developments should be meticulously documented and published swiftly, so policy can be changed if necessary, before it is too late. Cognizance of their existence, not necessarily frequency and statistics, is then first order. Efforts to design prognosticating tools has also high priority.