Vesicoureteric Junction Obstruction Research Articles

FURTHER EXPERIENCE WITH LAPAROSCOPIC NEPHRECTOMY FOR WILMS’ TUMOUR AFTER CHEMOTHERAPY

There are four papers in this section, from Turkey, Japan and two from Brazil. The topics dealt with are VUR, PUJ and vesico-ureteric junction obstruction, the non-pharmocological treatment of lower urinary tract dysfunction, and laparoscopic nephrectomy for Wilms’ tumour after chemotherapy. OBJECTIVE To report the results of laparoscopic nephrectomy for unilateral Wilms’ tumour in children treated with chemotherapy before surgery. PATIENTS AND METHODS Eight children with unilateral nonmetastatic Wilms’ tumour included in the International Society of Pediatric Oncology 2001 protocol were treated with vincristine/actinomycin D and then had laparoscopic nephrectomy and lymph-node sampling. A Veress needle puncture was made and a four-trocar transperitoneal approach was used in all cases. The tumour was extracted with no morcellation through a Pfannenstiel incision. RESULTS All eight tumours were completely removed, with lymph node samples; intraoperative bleeding was minimal (50 mL). There were no complications after surgery and patients were discharged after 2–3 days. No recurrences of disease, port-site implantation or long-term complications were detected. CONCLUSIONS Laparoscopic nephrectomy for unilateral Wilms’ tumour is feasible in children after chemotherapy; it is safe and allows the complete surgical approach required for treating this tumour. Although the patients had a good long-term follow-up, more patients are needed to compare the results of laparoscopic techniques with open surgery.

Subureteral Dextranomer/Hyaluronic Acid Injection as First Line Treatment in the Management of High Grade Vesicoureteral Reflux

Endoscopic correction of vesicoureteral reflux has become an established alternative to long-term antibiotic prophylaxis and ureteral reimplantation. A number of tissue augmenting substances have been used for the endoscopic correction of vesicoureteral reflux. We prospectively evaluated the effectiveness of dextranomer/hyaluronic acid copolymer (Deflux) as first line treatment for high grade vesicoureteral reflux. Between 2001 and 2004, 692 children with a median age of 2.1 years (3 months to 13.7 years) with high grade vesicoureteral reflux underwent endoscopic subureteral injection of Deflux soon after the diagnosis of vesicoureteral reflux was made on the initial voiding cystourethrogram. Vesicoureteral reflux was unilateral in 283 patients and bilateral in 409. Of the 1,101 ureters vesicoureteral reflux was grade II to V in 35 (3.2%), 580 (52.7%), 457 (41.5%) and 29 (2.6%), respectively. The procedure was performed on an outpatient basis. Followup ultrasound and voiding cystourethrogram were performed 3 months after the procedure, and renal and bladder ultrasound was done annually. Reflux resolved after first, second and third endoscopic Deflux injections in 952 (86.5%), 130 (11.8%) and 19 ureters (1.7%), respectively. Followup ultrasound revealed no evidence of delayed vesicoureteral junction obstruction. Of the patients 18 (2.6%) had urinary tract infection during followup after successful vesicoureteral reflux correction. Endoscopic subureteral injection of Deflux is excellent first line treatment in children with high grade vesicoureteral reflux. This 15-minute outpatient procedure is safe and simple to perform, and it can be easily repeated in failed cases.

Anterior Urethral Valves

We studied the clinical presentation and management of four patients with anterior urethral valves; a rare cause of urethral obstruction in male children. One patient presented antenatally with oligohydramnios, bilateral hydronephrosis and bladder thickening suggestive of an infravesical obstruction. Two other patients presented postnatally at 1 and 2 years of age, respectively, with poor stream of urine since birth. The fourth patient presented at 9 years with frequency and dysuria. Diagnosis was established on either micturating cystourethrogram (MCU) (in 2) or on cystoscopy (in 2). All patients had cystoscopic ablation of the valves. One patient developed a postablation stricture that was resected with an end-to-end urethroplasty. He had an associated bilateral vesicoureteric junction (VUJ) obstruction for which a bilateral ureteric reimplantation was done at the same time. On long-term follow-up, all patients demonstrated a good stream of urine. The renal function is normal. Patients are continent and free of urinary infections. Anterior urethral valves are rare obstructive lesions in male children. The degree of obstruction is variable, and so they may present with mild micturition difficulty or severe obstruction with hydroureteronephrosis and renal impairment. Hence, it is important to evaluate the anterior urethra in any male child with suspected infravesical obstruction. The diagnosis is established by MCU or cystoscopy and the treatment is always surgical, either a transurethral ablation or an open resection. The long-term prognosis is good.

Diagnostic difficulties in children with coexisting pelvi‐ureteric and vesico‐ureteric junction obstruction

To assess the diagnosis of children with coexisting pelvi-ureteric junction (PUJ) and vesico-ureteric junction (VUJ) obstruction, and the management of such patients, as having these two anomalies in the same ureter creates serious diagnostic difficulties, but any delay in diagnosis might cause a deterioration of renal function and affect the success of surgery to correct either anomaly. We assessed the diagnostic difficulties and approach to 14 patients with coexistent PUJ and VUJ obstruction, who were treated surgically in our clinic between 1994 and 2005; we also review related published reports in English. Surgery was used in all 14 patients over the 11-year period; only five patients had an accurate diagnosis before surgery. Six patients were diagnosed with uroradiological techniques immediately after pyeloplasty; three were diagnosed on investigating an associated anomaly later. In children with coexisting PUJ and VUJ obstruction there are serious diagnostic problems; to prevent any deterioration in renal function due to obstruction, these anomalies require early diagnosis and treatment. For an early and accurate diagnosis, the coexistence of these two anomalies in the same ureter should be considered.

Further experience with laparoscopic nephrectomy for Wilms’ tumour after chemotherapy

To report the results of laparoscopic nephrectomy for unilateral Wilms' tumour in children treated with chemotherapy before surgery. Eight children with unilateral nonmetastatic Wilms' tumour included in the International Society of Pediatric Oncology 2001 protocol were treated with vincristine/actinomycin D and then had laparoscopic nephrectomy and lymph-node sampling. A Veress needle puncture was made and a four-trocar transperitoneal approach was used in all cases. The tumour was extracted with no morcellation through a Pfannenstiel incision. All eight tumours were completely removed, with lymph node samples; intraoperative bleeding was minimal (50 mL). There were no complications after surgery and patients were discharged after 2-3 days. No recurrences of disease, port-site implantation or long-term complications were detected. Laparoscopic nephrectomy for unilateral Wilms' tumour is feasible in children after chemotherapy; it is safe and allows the complete surgical approach required for treating this tumour. Although the patients had a good long-term follow-up, more patients are needed to compare the results of laparoscopic techniques with open surgery.

Coexisting pelviureteral and vesicoureteral junction obstruction in children: C. Pesce, L. Musi, P. Campobasso, et al. Eur J Pediatr Surg 13:367–371, (December), 2003

Coexisting pelviureteral and vesicoureteral junction obstruction in children: C. Pesce, L. Musi, P. Campobasso, et al. Eur J Pediatr Surg 13:367–371, (December), 2003

Coexisting pelviureteral and vesicoureteral junction obstruction in children.

To address reasons for diagnostic failure in children with coexisting pelviureteral and vesicoureteral junction obstruction. A total of 11 children with coexisting pelviureteral and vesicoureteral junction obstruction are reported. This anomaly was recognised at presentation in only 5 (45%) of cases. In the remainder, correct diagnosis was made after initial pyeloplasty and a significant delay occurred in 3 children. In all 11 patients treatment consisted of pyeloplasty and subsequent reimplantation. A satisfactory postoperative course with improvement of urinary tract dilatation was noted in all 11 patients, while 8 of 11 patients showed preserved renal function at late follow-up. According to the few available data, our data confirm the difficulty of diagnosing coexisting pelviureteral and vesicoureteral junction obstruction in children. However, prompt recognition and relief of urinary obstruction in these patients is mandatory in order to prevent deterioration of renal function.

Obstructive uropathy in two Chinese patients with lupus interstitial cystitis

We report herein two patients who presented with bilateral hydronephrosis attributed to lupus cystitis with two totally different clinical consequences. Both had systemic lupus erythematosus complicated with nephritis and nephrotic range of proteinuria. During the investigation of their proteinuria, they were noted to have a dilated collecting system. The site of obstruction was localized at the vesicoureteric obstruction by excretory urogram. The hydronephrosis resolved spontaneously in one patient before the commencement of any medical therapy, whereas in the other patient, there was no response to steroid therapy. Augmentation enterocystoplasty was thus performed. Reversible hydronephrosis caused by vesicoureteric junction obstruction in patients with systemic lupus erythematosus has been reported. Immune-mediated vasculitis involving the ureter and bladder mucosa was the postulated pathogenic mechanism. The condition usually showed good clinical response upon immunosuppressive therapy. We conclude that systemic lupus erythematosus-associated interstitial cystitis can have a spectrum of different prognoses.

Neonatal surgical problems of the renal tract

A significant number of neonates have problems involving the renal tract that may have surgical implications. Although previously presentation was with urosepsis and renal failure, prenatal detection now identifies large cohorts of asymptomatic neonates with urinary tract dilatation that require neonatal investigation. Bladder outflow obstruction must be diagnosed early and relieved surgically. Patients with upper tract obstruction accompanied by reduced function or bilateralsingle kidney involvement should undergo early pyeloplasty. Vesicoureteric junction obstruction with compromised renal function or symptoms may require temporary double J stent insertion, ureterostomy or reimplantation. Severe urosepsis or vesical dysfunction, as in the neuropathic bladder, may necessitate vesicostomy diversion. Most renal anomalies, however, can be managed conservatively, for example multicystic dysplastic kidney and vesicoureteric reflux. The care of bladder exstrophy patients has now become supra-regional with the aim of concentrating experience and hopefully improving clinical outcomes in terms of urinary continence, genital appearance and function.

The use of renal scintigraphy in assessing the potential for recovery in the obstructed renal tract in children.

To assess the value of renal scintigraphy with 99mTc-dimercaptosuccinic acid (DMSA) in predicting functional recovery after the surgical relief of obstructed kidneys in children. Patients and methods Forty-three children underwent surgery to relieve upper urinary tract obstruction; 37 had pelvi-ureteric junction obstruction and six had vesico-ureteric junction obstruction. The indication for surgery was a combination of an obstructed renogram with symptoms of either pain or pyelonephritis. Most children (41) had < 40% function on the affected side before surgery, with just two having hyperfunction (> 55%). In all patients intravenous urography before surgery showed hydronephrosis, and a micturating cystogram was used to exclude coexisting reflux in the presence of an associated megaureter. Diuretic renography (using 99mTc-mercaptoacetyl triglycine or 123I-hippuran) and DMSA scintigraphy were both carried out before surgery and the renography repeated 6 months afterward. The renographic drainage curves improved from obstructed to unobstructed or 'dilated unobstructed' on all postoperative studies. Regression analysis showed that preoperative DMSA scan was an excellent predictor of outcome (P < 0.001) whilst the preoperative renogram was a relatively poor predictor of the functional result. In four patients where the initial renographic function was < 10%, DMSA scintigraphy predicted correctly the capacity for recovery in three and the inability to improve in the fourth. Conclusion Before surgery, DMSA scintigraphy in children with upper urinary tract obstruction is a more useful estimate of probable long-term renal function than value from diuresis renography. If there is doubt about the desirability of reconstructive surgery, a DMSA scan may eliminate the need for more invasive methods of estimating recovery, e.g. a period of nephrostomy drainage.

Long-term prognosis of renal function in boys treated for posterior urethral valves.

This paper discusses the long-term prognosis of renal function in 84 boys treated for posterior urethral valves and followed up for a period ranging from 1-21 years. Thirty-one of the 84 patients (39.3%) were either adolescents or had crossed adolescence and this study highlights the changes through adolescence and puberty. Serum creatinine was found to be raised in 53% patients at presentation and 22.5% patients eventually progressed to chronic renal failure. Serum creatinine value 1 year after appropriate decompression of the urinary tract was a more accurate predictor of the eventual renal outcome rather than serum creatinine at presentation. Decompensation at puberty was detected in 3 patients in this study. The predisposing factors identified were the persistence of gross hydroureteronephrosis with voiding dysfunction after treatment in one patient and renal parenchymal disease in the other 2 patients. The "risk factors" for predicting a poor eventual renal function were persistently raised serum creatinine 1 year after decompression by diversion or fulguration, bilateral high grade vesicoureteral reflux, persistent severe upper tract dilatation after treatment, voiding dysfunction and delayed presentation. This study emphasizes the need to diagnose and intervene early, to investigate post-treatment persistent upper tract dilatation for vesicoureteral junction obstruction and for detrusor dysfunction by a complete urodynamic evaluation and to follow up these patients carefully through adolescence and adulthood.

F+0 diuresis renography in infants and children

UNLABELLED The purpose of this study was to evaluate the feasibility of modifying diuresis renography by the simultaneous administration of 99mTc-mercaptoacetyltriglycine (MAG3) and furosemide in the investigation of hydronephrosis and hydroureteronephrosis in infants and children. Two parameters were assessed: the diuretic response in normal kidneys and the ability of the F+0 study to differentiate between renal obstruction and nonobstruction and to identify the level of obstruction in cases of renal obstruction. METHODS Seventy-two patients (48 males, 24 females; age 2 d to 7 y; median age 6 wk) with sonographic diagnoses of hydronephrosis or hydroureteronephrosis were reviewed prospectively over a 3-y period. All patients had prior sonographic studies and micturating cystourethrography. Bladder catheterization was not routinely performed and was undertaken only if the child had suspected vesicoureteric junction (VUJ) obstruction or grade II or more vesicoureteric reflux. A weight-adjusted dose of 99mTc-MAG3 (maximum 200 MBq, minimum 20 MBq) and 1 mg/kg of furosemide (maximum 40 mg) were administered intravenously at the same time. Posterior imaging of the kidneys and bladder was performed for 20 min and followed by gravity-assisted drainage or imaging after voiding. All patients were followed-up for 6-12 mo, and the final diagnoses were based on either surgery or conservative management with repeated sonography or follow-up 99mTc-MAG3 studies (or both). The results of the F+0 diuresis renography were then compared with the final diagnoses. RESULTS A renal unit was defined as a kidney and its ureter. There were 151 renal units with 1 patient having bilateral duplex kidneys, 6 patients having unilateral duplex kidneys and 1 patient having a solitary kidney. Fifty-five normal renal units and 96 abnormal renal units on the basis of sonographic findings were assessed. The furosemide clearance half-time for the 55 normal renal units was 1.3-6.3 min (mean 3.8 min). Of the 96 abnormal renal units, 53 were classified as nonobstructed and 43 were classified as obstructed. Of the 53 renal units classified as nonobstructed, there were 48 true-negative studies and 5 false-negative studies; of the 43 renal units classified as obstructed, there were 40 true-positive studies and 3 false-positive studies. The sensitivity was 88.9%, specificity was 94.1% and accuracy was 91.7%. The level of obstruction, either pelviureteric junction or VUJ, was also correctly identified. CONCLUSION F+0 diuresis renography shows excellent diuretic responses in normal kidneys and is a valid method for the investigation of hydronephrosis and hydroureteronephrosis in infants and children.

MULTICENTER SURVEY OF ENDOSCOPIC TREATMENT OF VESICOURETERAL REFLUX USING POLYTETRAFLUOROETHYLENE

Purpose Endoscopic subureteral polytetrafluoroethylene (Teflon) injection has been used successfully to treat primary and secondary vesicoureteral reflux in children. We review the results of subureteral polytetrafluoroethylene injection in terms of its effectiveness, long-term followup and morbidity. Materials and Methods A total of 53 pediatric urologists and/or pediatric surgeons at 41 centers worldwide answered an inquiry regarding experience with subureteral polytetrafluoroethylene injection in vesicoureteral reflux. Data were collected from a completed standard questionnaire. From 1984 to 1996, 1,921 boys and 6,411 girls with a mean age of 4.5 years (12,251 refluxing ureters) were treated endoscopically with subureteral polytetrafluoroethylene injection. Reflux was grades I to V in 407 (3.3%), 3,832 (31.2%), 5,213 (42.5%), 2,218 (18.1%) and 581 (4.7%) ureters, respectively. In the majority of patients subureteral polytetrafluoroethylene injection was performed on an outpatient basis. Most urologists monitored patients with voiding cystourethrography and renal ultrasound at 3 months, 1 year and 3 years. All patients were followed 1 to 13 years. Results Reflux resolved in 9,226 ureters (75.3%) after 1 polytetrafluoroethylene injection, in 1,478 (12%) after 2 and in 250 (2%) after 3 or 4. Vesicoureteral reflux improved to grade I after 1 or 2 injections in 743 (6%) ureters, which needed no further treatment. Subureteral injection failed to correct reflux in 554 ureters (4.5%), which were then treated with ureteral reimplantation. Vesicoureteral junction obstruction requiring ureteral reimplantation developed in 41 ureters (0.33%). More than 90% of patients have been followed for more than 2 years. At followup reflux recurred in 326 (2.8%) endoscopically corrected refluxing ureters. No clinically untoward effects were reported in any patient due to the use of polytetrafluoroethylene as an injectable material. Conclusions The results of this multicenter survey confirm that endoscopic subureteral polytetrafluoroethylene injection is a simple, safe and effective outpatient procedure for treating all grades of vesicoureteral reflux.

Multicenter survey of endoscopic treatment of vesicoureteral reflux using polytetrafluoroethylene.

Endoscopic subureteral polytetrafluoroethylene (Teflon) injection has been used successfully to treat primary and secondary vesicoureteral reflux in children. We review the results of subureteral polytetrafluoroethylene injection in terms of its effectiveness, long-term followup and morbidity. A total of 53 pediatric urologists and/or pediatric surgeons at 41 centers worldwide answered an inquiry regarding experience with subureteral polytetrafluoroethylene injection in vesicoureteral reflux. Data were collected from a completed standard questionnaire. From 1984 to 1996, 1,921 boys and 6,411 girls with a mean age of 4.5 years (12,251 refluxing ureters) were treated endoscopically with subureteral polytetrafluoroethylene injection. Reflux was grades I to V in 407 (3.3%), 3,832 (31.2%), 5,213 (42.5%), 2,218 (18.1%) and 581 (4.7%) ureters, respectively. In the majority of patients subureteral polytetrafluoroethylene injection was performed on an outpatient basis. Most urologists monitored patients with voiding cystourethrography and renal ultrasound at 3 months, 1 year and 3 years. All patients were followed 1 to 13 years. Reflux resolved in 9,226 ureters (75.3%) after 1 polytetrafluoroethylene injection, in 1,478 (12%) after 2 and in 250 (2%) after 3 or 4. Vesicoureteral reflux improved to grade I after 1 or 2 injections in 743 (6%) ureters, which needed no further treatment. Subureteral injection failed to correct reflux in 554 ureters (4.5%), which were then treated with ureteral reimplantation. Vesicoureteral junction obstruction requiring ureteral reimplantation developed in 41 ureters (0.33%). More than 90% of patients have been followed for more than 2 years. At followup reflux recurred in 326 (2.8%) endoscopically corrected refluxing ureters. No clinically untoward effects were reported in any patient due to the use of polytetrafluoroethylene as an injectable material. The results of this multicenter survey confirm that endoscopic subureteral polytetrafluoroethylene injection is a simple, safe and effective outpatient procedure for treating all grades of vesicoureteral reflux.

Upper-tract changes after treatment of posterior urethral valves.

This paper discusses the long-term sequelae in the upper urinary tract with respect to hydroureteronephrosis (HUN), vesicoureteral reflux (VUR), renal parenchymal disease, and their correlation with renal function in 84 boys with posterior urethral valves followed for 1 to 21 years. Thirty-one boys (39.3%) were adolescents or older at the time of review. The incidence of high-grade VUR (grade III or more) was 47.6% at presentation, and resolution following decompression of the lower urinary tract occurred in 38.7% of refluxing units. VUR was associated with a high incidence of chronic renal failure (CRF) (30%) on long-term follow up; however, 16% of non-refluxing patients also progressed to CRF. The incidences of renal parenchymal disease and persistent upper-tract dilatation in the non-refluxing group were 25% and 50% of renal units respectively. Gross HUN persisted in 12.3% of patients despite decompression and reconstructive surgery, with vesicoureteral junction (VUJ) obstruction being documented in 1 patient only. Moderate and mild upper-tract dilatation persisted in 31.6% and 43.9% of patients, respectively. Persistent gross HUN was associated with a very high incidence of CRF (92.3%), while 88.4% of those with persistent mild/moderate dilatation maintained normal renal function over a follow-up period ranging from 1 to 21 years. This study emphasizes the need for systematic evaluation to exclude VUJ obstruction and abnormal urodynamics as a cause of persistent HUN so that effective therapy can be instituted early to relieve back-pressure and to provide a low-pressure reservoir with effective emptying. In the absence of either of these causes, persistent ureterectasis after treatment is presumably due to secondary peristaltic failure as a consequence of ureteral fibrosis, ureteral tortuosity, or developmental dysplasia.

Neonatal urinary ascites due to unilateral vesicoureteric junction obstruction

Neonatal urinary ascites due to unilateral vesicoureteric junction obstruction

Balloon dilatation of the pelviureteric junction in children: early experience and pitfalls.

Early experience with minimally invasive procedures performed on children with pelviureteric junction obstruction is described. Balloon dilatation of the pelviureteric junction was performed in children aged between 5 months and 10 years. Ten procedures were performed in nine children, six for pelviureteric junction obstruction and four for stricture following surgical pyeloplasty. In none of the cases was a stent inserted following the procedure. In two cases the procedure was performed by antegrade approach following nephrostomy and in eight cases by retrograde approach following cystoscopy. In four cases the procedure was successful with relief of symptoms and/or improvement in radiological appearance, in three cases the radiological appearance was unchanged and in three cases the procedure resulted in complete obstruction of the pelviureteric junction requiring surgical intervention. Two of the retrograde procedures resulted in vesicoureteric junction obstruction, one requiring reimplantation and the other nephrectomy. We recommend the antegrade approach to avoid trauma to the vesicoureteric junction, and our results suggest that stenting is necessary to prevent early obstruction.

Endoscopic treatment of vesico-ureteric reflux in neurogenic bladder—8 Years' experience

During an 8-year period, 51 children with neurogenic bladder had endoscopic injection of Teflon (STING) for the management of 69 refluxing ureters. There were 21 boys and 30 girls (age range, 10 month to 16 years). Vesico-ureteral reflux (VUR) had been present for a mean of 4.1 years, and severity distribution was as follows: grade I, 1 ureter; grade II, 5 ureters, grade III, 9 ureters; grade IV, 39 ureters; and grade V, 15 ureters. The follow-up period ranged from 3 months to 8 years (mean, 4 years). Reflux ceased in 57 ureters (82%); in four ureters the VUR recurred (9 months to 6 years later). Bilateral vesico-ureteric junction (VUJ) obstruction occurred in one patient, which required surgical correction 3 years after STING. These data suggest that for difficult cases of VUR in neurogenic bladders, STING is a safe and effective option and should be the initial treatment of choice. However, because of the possibility of late recurrence of VUR or obstruction at the VUJ, long-term follow-up is required.

Subureteric Teflon Injection (STING)

Subureteric Teflon injection (STING) has been successfully used by several investigators for treating vesicoureteric reflux (VUR) in children. This multicentre European survey reviews the results of STING in 6,216 ureters. Twenty-two paediatric surgeons/urologists from 18 centres in Europe answered an enquiry regarding their experience with STING in the treatment of VUR. 6,216 refluxing ureters were injected with Polytef paste in 4,166 children during 1984-1990. There were 975 boys and 3,191 girls. Their ages ranged from 2 months to 14 years (mean 5.1 years). The reflux was grade I in 4.4% of ureters, grade II in 36.1%, grade III in 40.2%, and grades IV and V in 19.3% of ureters. All patients were followed up for periods ranging from 3 months to 81/2 years and 90% were followed up for more than 2 years. 76.3% of all ureters stopped refluxing after a single injection of Teflon paste, cure rate increased to 84.9% after a second injection. A further 10.2% of refluxing ureters showed significant improvement in the grade of reflux after a single injection and needed no further treatment. 1.3% of ureters were cured after a third or fourth injection. Failure to correct or improve VUR was seen in 224 ureters (3.6%), necessitating reimplantation. Twenty ureters (0.32%) developed vesicoureteric junction obstruction following STING and these were reimplanted without difficulty. Results of this multicentre survey confirm that STING is an effective day care procedure for treatment of all grades of VUR. 95% of all ureters were cured or showed significant improvement after two injections of Teflon paste.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Outcome and Management of Prenatally Diagnosed Primary Megaureters

The objective of this study was to evaluate the clinical outcome of infants diagnosed perinatally with primary obstructive megaureter, and to determine which anatomical and physiological indexes best predict such outcome. A total of 67 megaureters thought to be due to primary vesicoureteral junction obstruction was detected in 53 newborns as a result of prenatally diagnosed hydronephrosis or hydroureteronephrosis. These patients were followed nonoperatively using periodic ultrasound and 99mtechnetium-diethylenetriaminepentaacetic acid (Tc-DTPA) renal scans. After a mean followup period of 3.1 years 23 dilated ureters (34%) spontaneously resolved while 33 (49%) persisted. Repair was performed on 11 megaureters (17%) because of breakthrough urinary infections in 3 and deteriorating renal function in 8. Postoperatively, all renal units showed improved drainage on 99mTc-DTPA renal scan, while half of those with decreased renal function regained the lost function. None had further deterioration in renal function.Of the clinical indexes studied ultrasonographic ureteral diameter (less than 6mm. good, greater than 10mm. poor prognosis) and drainage on 99mTc-DTPA renal scan correlated best with outcome. We conclude that the majority of primary megaureters detected in the perinatal period can be followed conservatively using periodic ultrasound and 99mTc-DTPA renal scans. Relatively few cases required surgical intervention and those at risk were identifiable by a diameter greater than 10mm. and poor drainage on 99mTc-DTPA renal scan.