Treatment with nephrectomy only for small, stage I/favorable histology Wilms' tumor: a report from the National Wilms' Tumor Study Group.

PURPOSE: Children younger than 24 months with small (< 550 g), favorable histology (FH) Wilms tumors (WTs) were shown in a pilot study to have an excellent prognosis when treated with nephrectomy only. PATIENTS AND METHODS: A study of nephrectomy only for the treatment of selected children with FH WT was undertaken. Stringent stopping rules were designed to insure closure of the study if the true 2-year relapse-free survival rate was 90% or lower. RESULTS: Seventy-five previously untreated children younger than 24 months with stage I/FH WTs for which the surgical specimen weighed less than 550 g were treated with nephrectomy only. Three patients developed metachronous, contralateral WT 1.1, 1.4, and 2.3 years after nephrectomy, and eight patients relapsed 0.3 to 1.05 years after diagnosis (median, 0.4 years; mean, 0.51 years). The sites of relapse were lung (n = 5) and operative bed (n = 3). The 2-year disease-free (relapse and metachronous contralateral WT) survival rate was 86.5%. The 2-year survival rate is 100% with a median follow-up of 2.84 years. The 2-year disease-free survival rate (excluding metachronous contralateral WT) was 89.2%, and the 2-year cumulative risk of metachronous contralateral WT was 3.1%. CONCLUSION: Children younger than 24 months treated with nephrectomy only for a stage I/FH WT that weighed less than 550 g had a risk of relapse, including the development of metachronous contralateral WT, of 13.5% 2 years after diagnosis. All patients who experienced relapse on this trial are alive at this time. This approach will be re-evaluated in a clinical trial using a less conservative stopping rule.

Controversies in the management of Wilms' tumor.

Wilms' tumor is the most common malignant renal tumor of childhood; it represents 5% to 6% of childhood cancers in the United States. The survival rate of children with Wilms' tumor has improved dramatically, partly due to large multicenter studies conducted by the National Wilms' Tumor Study Group and the International Society of Pediatric Oncology. To ensure optimal patient outcome, the surgical management of these patients must be appropriate. Controversial issues in the management of Wilms' tumor include the value of preoperative chemotherapy; whether pre-resection biopsy is indicated and if so, how this is best performed; indications for partial nephrectomy; the treatment of low-risk patients with surgery only; and the reliability of preoperative imaging to assess the contralateral kidney.

Advantages of rectus fascial slings for urinary incontinence in children with neuropathic bladders.

PURPOSE: Many surgical procedures to improve outlet resistance in children with neuropathic bladders are obstructive and increase the detrusor leak point pressure. In contrast, fascial slings are designed to achieve continence by increasing the Valsalva or stress leak point pressure without altering the detrusor leak point pressure. We evaluate the effectiveness of fascial slings in achieving continence in pediatric patients with neuropathic bladder. MATERIALS AND METHODS: From October 1994 until February 1999, 10 females and 8 males with neuropathic bladder secondary to myelodysplasia or traumatic spinal cord injury underwent fascial sling procedures. Mean patient age was 14 years (range 8 to 18) and all were incontinent despite aggressive medical management. Urodynamic evaluation was performed preoperatively and postoperatively. Specific urodynamic measurements included detrusor leak point pressure, stress leak point pressure and detrusor compliance. Compliance was only compared in the 12 nonaugmented cases. RESULTS: With a mean followup of 21.2 months (range 6 to 57), preoperative and postoperative urodynamics revealed little change in mean detrusor leak point pressure (23.2 versus 23.22 cm. H2O) but a substantial increase in mean stress leak point pressure (41.6 versus 64.5 cm. H2O). Mean compliance was unchanged in the nonaugmented group (22.00 versus 26.78 ml/cm. H2O). Four patients (22.22%) remained wet after surgery, of whom 2 were successfully treated with a repeat sling procedure and 1 with collagen injection for an overall continence rate of 94.44%. CONCLUSIONS: Fascial slings can be effectively used in pediatric patients for neuropathic incontinence. Furthermore, stress urinary incontinence is corrected by increasing the Valsalva or stress leak point pressure with preservation of the detrusor leak point pressure. Preservation of detrusor leak point pressure is particularly advantageous because other forms of bladder outlet procedures achieve continence at the expense of increasing detrusor pressures, thus placing the upper tracts at risk for damage.

Intravascular extension of Wilms tumor.

OBJECTIVE: To define the incidence and manifestations of and optimal therapy for children with intravascular extension of Wilms tumor. METHODS: Children on a collaborative study of Wilms tumor who had intravascular extension into the inferior vena cava (IVC) or atrium were identified. Surgical checklists and surgical and pathology reports were reviewed. RESULTS: One hundred sixty-five of 2,731 patients had intravascular extension of Wilms tumor. The level of extension was IVC in 134 and atrium in 31. Sixty-nine had received preoperative therapy (55 with IVC extension and 14 with atrial extension) for a median of 8 weeks. Complications during preoperative chemotherapy were seen in five patients (tumor embolism and tumor progression in one each, and three with adult respiratory distress syndrome, one of which was fatal). The intravascular extension of the tumor regressed in 39 of 49 children with comparable pre- and posttherapy radiographic studies, including 7 of 12 in whom the tumor regressed from an atrial location, thus obviating the need for cardiopulmonary bypass. Surgical complications occurred in 36.7% of the children in the atrial group and 17.2% in the IVC group. The frequency of surgical complications was 26% in the primary resection group versus 13.2% in children with preoperative therapy. When all the complications of therapy were considered, including those that occurred during the interval of preoperative chemotherapy (one of the five also had a surgical complication), the incidence of complications among those receiving preoperative therapy was not statistically different from the incidence among those who underwent primary resection. The difference in 3-year relapse-free survival (76.9% for 165 patients with intravascular extension, 80.3% for 1,622 patients with no extension) was not statistically significant whether or not it was adjusted for stage and histology. CONCLUSIONS: Preoperative treatment of these children may facilitate resection by decreasing the extent of the tumor thrombus, but the overall frequency of complications is similar in both groups.

Surgical complications after primary nephrectomy for Wilms' tumor: report from the National Wilms' Tumor Study Group.

BACKGROUND: Surgical complications are a recognized morbidity of the treatment of patients with Wilms tumor. This study examines the incidence of surgical complications in the most recently completed study from the National Wilms' Tumor Study Group (NWTSG). STUDY DESIGN: The fourth National Wilms' Tumor Study (NWTS-4) enrolled 3,335 patients from August 1986 to August 1994. A random sample of 534 patients was selected from 2,290 eligible patients randomized to treatment regimens or enrolled in the followed category and treated according to NWXTSG protocol. The patient records received at the NWTSG Data and Statistical Center were analyzed for surgical complications (intraoperative and postoperative). RESULTS: Sixty-eight patients (12.7%) experienced 76 complications. Intestinal obstruction was the most common complication (5.1% of patients), followed by extensive hemorrhage (1.9%), wound infection (1.9%), and vascular injury (1.5%). The incidence of surgical complications in NWTS-4 was significantly lower than NWTS-3 (12.7% versus 19.8%, p < 0.001). There has been a marked decrease in the risk of extensive intraoperative bleeding and major intraoperative complications. Factors previously shown to be associated with an increased risk for surgical complications, together with indicators of type of hospital and surgeon specialty, were analyzed by multiple logistic regression analysis. Intravascular extension into the inferior vena cava (IVC), the atrium, or both (p = 0.02; odds ratio [OR] 3.8, 95% confidence interval [CI] 1.2, 11.8), and nephrectomy performed through a flank or paramedian incision (p = 0.02; OR 5.3, 95% CI 1.3, 22) were both associated with increased risk of complications. Tumor diameter greater than or equal to 10cm was also associated with an increased risk of surgical complications (p = 0.05; OR 2.0, 95% CI 1.0, 3.9). The risk of complications was higher if the nephrectomy was performed by a general surgeon (OR 9.0, 95% CI 1.3, 65; p = 0.03) rather than a pediatric surgeon (reference group, OR 1.0) or pediatric urologist (OR 0.7, 95% CI 0.3, 1.8). CONCLUSIONS: The incidence of surgical complications in NWTSG patients undergoing primary nephrectomy has significantly decreased over the past decade. But surgical morbidity should not be overlooked. It is important that surgeons treating young children with solid tumors are aware of their role and the potential risks encountered in removal of the primary tumor. This study found that surgical specialists who primarily treat children can perform these operations with lower surgical morbidity.

Recent progress in the biology and treatment of Wilms' tumor.

The survival rate of patients with Wilms' tumor has rapidly improved in the last few decades. As we enter into the new millennium, overall survival for all Wilms' tumor patients exceeds 80%. Two large cooperative groups prospectively studied children with nephroblastoma: the National Wilms' Tumor Study Group, and the International Society of Paediatric Oncology. This review details the recent progress in understanding the biology of Wilms' tumor. Advances in clinical management of children with nephroblastoma are also outlined.

Wilms' tumor. Overview of National Wilms' Tumor Study Group results.

Since its inception in 1969, the NWTSG has performed successful studies that are now the model for the management of pediatric malignancies. Future studies may use genetic markers to stratify high-risk patients beyond the traditional staging system. Therapy will continue to be evaluated to determine the minimal therapy necessary to achieve the best outcome for children with Wilms' tumor.

Renal failure in the Denys-Drash and Wilms' tumor-aniridia syndromes.

Nearly 6000 patients enrolled in four clinical trials of the National Wilms' Tumor Study Group during 1969-1995 were followed until death or for a median of 11.0 years of survival for the onset of renal failure (RF). Thirteen of 22 patients with Denys-Drash syndrome and 10 of 46 patients with the Wilms' tumor aniridia syndrome developed RF. The cumulative risks of RF at 20 years from Wilms' tumor diagnosis were 62% and 38%, respectively. Only 21 cases of RF were observed among 5358 patients with unilateral disease who did not have characteristic congenital genitourinary anomalies, and their risk was <1%. Although other explanations cannot be completely excluded, the high rate of RF in patients with the aniridia syndrome challenges the view that nephropathy is associated uniquely with missense mutations in the WT1 gene. It suggests the possibility of a further gradation in the spectrum of phenotypes associated with different WT1 mutations. Patients with Wilms' tumor and aniridia or genitourinary abnormalities should be followed closely throughout life for signs of nephropathy or RF.

Congenital anterior urethrocutaneous fistula.

PURPOSE: Congenital anterior urethrocutaneous fistula is a rare anomaly that may present in an isolated fashion or in association with other penile abnormalities, such as chordee or hypospadias. There have been 18 cases of congenital anterior urethrocutaneous fistula reported in the literature. We present 14 additional cases of congenital anterior urethrocutaneous fistula. MATERIALS AND METHODS: We treated 14 patients with congenital anterior urethrocutaneous fistula, of whom 9 were uncircumcised at presentation. Two patients had evidence of chordee and 4 had distal hypospadias. RESULTS: The type of repair was determined by the anatomical variations of this anomaly. All cases were corrected electively by various techniques based on the degree of the defect, including primary closure via a Thiersch-Duplay urethroplasty, pedicle flap urethroplasty, hinged flap urethroplasty and interpositioned island pedicle tube or onlay urethroplasty. CONCLUSIONS: To our knowledge the embryological events that cause anterior urethrocutaneous fistula are unclear but they likely result from a defective urethral plate or an abnormality of the infolding of the urethral groove. Surgical technique must be individualized to fit the defect. While there has been considerable skepticism regarding the existence of congenital urethrocutaneous fistula, the fact that 9 of our 14 patients were uncircumcised confirms the congenital nature of this lesion.

New concepts of histological changes in experimental augmentation cystoplasty: insights into the development of neoplastic transformation at the enterovesical and gastrovesical anastomosis.

PURPOSE: To our knowledge the pathogenesis of malignancy associated with ileal cystoplasty, ureterosigmoidostomy and ileal conduits is currently unknown. To gain further insights into the mechanism of neoplastic transformation we studied histological changes in a canine augmentation cystoplasty model. MATERIALS AND METHODS: Enterocystoplasty and gastrocystoplasty were performed using a 5 to 7 cm. patch of ileum in 8 dogs and gastric antrum in 6. Specimens were harvested 4 months postoperatively. Representative 3 microm sections of the enterovesical and gastrovesical junctions were stained with hematoxylin and eosin. Uroplakin expression was assessed using an indirect peroxidase method subjected to double staining with alcian blue and periodic acid-Schiffreagent. RESULTS: The bladder portion of the augmentation cystoplasty had 3 to 4 stratified cell layers covered with a distinctive umbrella cell layer. Strong uroplakin staining was visible in all cell layers except the basal layer. At the enterovesical and gastrovesical junctions 6 to 10 layers of hyperplastic, urothelial appearing cells covered the glandular epithelium of the ileal and gastric segments. These cells expressed uroplakins. At this junction zone there was a marked decrease of underlying enteric glands, which had atrophied in proportion to the degree of urothelial hyperplasia. Double staining of uroplakin stained sections with alcian blue and periodic acid-Schiff reagent revealed mucosubstances in hyperplastic urothelial cells covering the enteral segments, indicating that the cells co-expressed uroplakins and mucins. CONCLUSIONS: Histological changes in this experimental canine model of augmentation cystoplasty indicated that the overgrowth of hyperplastic transitional epithelium develops at the enterovesical and gastrovesical junctions. These cells express not only uroplakins, but also mucosubstances. Our results suggest that the migrated hyperplastic urothelial cells have undergone changes characteristic of the enteric and gastric epithelium, which may have important implications in the pathogenesis of malignancy in bladder augmentations.

Factors affecting the risk of contralateral Wilms tumor development: a report from the National Wilms Tumor Study Group.

BACKGROUND: Approximately 1% of children with unilateral Wilms tumor develop contralateral disease. The authors assessed the demographic and histologic features associated with metachronous bilateral Wilms tumor (BWT). METHODS: Characteristics of all children registered on the first four National Wilms Tumor Studies (NWTS) were recorded. The primary endpoint for evaluation was the first appearance of Wilms tumor in the remaining kidney. The cumulative risk of contralateral disease as a function of time since initial presentation was calculated as 1 minus the Kaplan-Meier estimate of remaining free of contralateral disease. A matched case control study was conducted to determine whether the presence and type of nephrogenic rests (NRs) were associated with metachronous BWT. RESULTS: Fifty-eight of 4669 registered children developed metachronous BWT; 38 of 2445 females (expected, 30.2) versus 20 of 2224 males (expected, 27.8) (P = 0.04) developed BWT. The cumulative incidence of contralateral disease 6 years after initial diagnosis decreased from greater than 3% in the first NWTS to approximately 1.5% in the three subsequent studies (P = 0.08). Patients with NRs had a significantly increased risk of metachronous BWT. This was particularly true for young children (20 of 206 age < 12 months compared with 0 of 304 age > 12 months). Data from the matched case control study confirmed the increased relative risk associated with young age and the presence of NRs. CONCLUSIONS: Children younger than 12 months diagnosed with Wilms tumor who also have NRs, in particular perilobar NRs, have a markedly increased risk of developing contralateral disease and require frequent and regular surveillance for several years. Surveillance is also recommended for those with NRs who are diagnosed after the age of 12 months.

The role of preoperative chemotherapy for Wilms' tumor: the NWTSG perspective. National Wilms' Tumor Study Group.

Extensive experience has been accumulated with the use of preoperative therapy for children with Wilms' tumor. In selected cases, preoperative chemotherapy can reduce the morbidity of treatment. This is most appropriate for children with bilateral tumors in whom parenchymal sparing procedures are desirable. Patients with inoperable tumors and extensive intravascular tumor extension can also benefit from this approach. The NWTSG recommendations for preoperative chemotherapy in patients with Wilms' tumor are presented.

Surgery-related factors and local recurrence of Wilms tumor in National Wilms Tumor Study 4.

OBJECTIVE: To assess the prognostic factors for local recurrence in Wilms tumor. SUMMARY BACKGROUND DATA: Current therapy for Wilms tumor has evolved through four studies of the National Wilms Tumor Study Group. As adverse prognostic factors were identified, treatment of children with Wilms tumor has been tailored based on these factors. Two-year relapse-free survival of children in the fourth study (NWTS-4) exceeded 91%. Factors once of prognostic import for local recurrence may lose their significance as more effective therapeutic regimens are devised. METHODS: Children evaluated were drawn from the records of NWTS-4. A total of 2482 randomized or followed patients were identified. Local recurrence, defined as recurrence in the original tumor bed, retroperitoneum, or within the abdominal cavity or pelvis, occurred in 100 children. Using a nested case-control study design, 182 matched controls were selected. Factors were analyzed for their association with local failure. Relative risks and 95% confidence intervals were calculated, taking into account the matching. RESULTS: The largest relative risks for local recurrence were observed in patients with stage III disease, those with unfavorable histology (especially diffuse anaplasia), and those reported to have tumor spillage during surgery. Multiple regression analysis adjusting for the combined effects of histology, lymph node involvement, and age revealed that tumor spillage remained significant. The relative risk of local recurrence from spill was largest in children with stage II disease. The absence of lymph node biopsy was also associated with an increased relative risk of recurrence, which was largest in children with stage I disease. The survival of children after local recurrence is poor, with an average survival rate at 2 years after relapse of 43%. Survival was dependent on initial stage: those who received more therapy before relapse had a worse prognosis. CONCLUSIONS: This study has demonstrated that surgical rupture of the tumor must be prevented by the surgeon, because spills produce an increased risk of local relapse. Both local and diffuse spills produce this risk. Stage II children with local spill appear to require more aggressive therapy than that used in NWTS-4. The continued critical importance of lymph node sampling in conjunction with nephrectomy for Wilms tumor is also established. Absence of lymph node biopsy may result in understaging and inadequate treatment of the child and may produce an increased risk of local recurrence.

Wilms tumour: diagnosis and treatment.

Wilms tumour is the most common intra-abdominal solid tumour of childhood. Treatment includes surgical resection and chemotherapy for virtually all affected children and additional radiotherapy for those with advanced disease or adverse prognostic features. This approach leads to cure rates exceeding 80%. During the last decade there have been a number of advances which have increased our understanding of the biology of Wilms tumour. The development of Wilms tumour, for example, involves several genes, including WT1, the Wilms tumour suppressor gene at 11p13, and WT2, the putative Wilms tumour suppressor gene at 11p15. In addition, certain chromosomal regions, most notably 16q and 1p, might predict outcome and hence serve as a prognostic factor, useful for determining the intensity of therapy. This novel information is now being incorporated into current therapeutic protocols. We reviewed the medical literature and present a summary of the advances made, outlining the current treatment of Wilms tumour. Future protocols will continue incorporating biological markers. The goal is to identify patients at low risk for relapse, which will allow a reduction in treatment intensity and subsequent toxicity. Children at an increased risk for relapse can be selected for more intensive treatment.

Anatomical alignment for the correction of buried penis.

PURPOSE: We report a straightforward surgical technique for the correction and anatomical alignment of the skin in patients with various degrees of buried penis. MATERIALS AND METHODS: A combined series of 74 patients 7 months to 10 years old who were treated for buried penis at 2 institutions during a 7-year period. Patients presented with various symptoms, including balanitis, urinary tract infection, painful voiding, ballooning of the foreskin and urinary retention. In 29 patients (38%) trapped penis was due to previous circumcision. In our estimation the major anatomical defect in buried penis is an insufficient attachment of the dartos fascia and penile skin to Buck's fascia. Our technique involves making a circumferential incision of the inner preputial skin layer proximal to the corona, unfurling it from the shaft skin and leaving a coronal collar of approximately 1 cm. The annular band that usually constricts the corpora on retraction of the penile skin is incised, and the remaining proximal penile skin and dartos fascia are dissected off Buck's fascia proximally to the base of the penis. The penile dermis is sutured to the lateral aspect of the tunica albuginea at the penopubic junction and mid shaft of the penis. This technique restores normal anatomical relationships with excellent cosmetic results and negligible complications. RESULTS: At a median 5-year followup cosmesis was excellent in all cases. Two patients with micropenis who required revision responded to endocrine therapy. CONCLUSIONS: Excellent cosmetic results were obtained in all cases using this surgical technique.

Ring block for neonatal circumcision.

OBJECTIVE: To determine whether a difference in the behavioral and physiologic response to circumcision can be demonstrated between neonates undergoing the procedure with ring block and those receiving no anesthesia. METHODS: Forty healthy male newborns were assigned randomly to receive either ring block or no anesthesia. Indices of perceived pain including crying time, behavioral state, oxygen saturation, and heart and respiratory rates were recorded at baseline and at intervals during the circumcision. Infants were reassessed 2 minutes and 2 hours postoperatively. RESULTS: Infants receiving ring block cried less than did controls (P < .001). Anesthetized infants had smaller increases in heart rate (P < .005) and demonstrated less arousal (P < .005) during each operative interval. For all operative intervals combined, anesthetized infants had a smaller decrease in oxygen saturation (P < .001) and a smaller increase in respiratory rate (P = .005) than did controls. Two minutes postoperatively, anesthetized infants had returned to their baseline behavioral state, whereas controls remained significantly more aroused (P < .005). Two hours postoperatively, there were no significant differences in any variables between the groups, nor between each group and its baseline. There were no complications related to anesthesia administration. CONCLUSION: Neonatal circumcision causes behavioral and physiologic changes consistent with the perception of pain. Ring block is an effective method of anesthesia for this procedure.

Current concepts in the biology and management of Wilms tumor.

PURPOSE: There have been a number of advances that have increased our understanding of the biology of Wilms tumor during the last decade. This information is now being incorporated into current pediatric oncology protocols. We present a summary of these advances and outline the current treatment of Wilms tumor. MATERIALS AND METHODS: The medical literature was reviewed with an emphasis on the molecular biology of Wilms tumor. RESULTS: The development of Wilms tumor involves several genes, including WT1, the Wilms tumor suppressor gene at 11p13. In addition, certain chromosomal regions (16q and 1p) might be used as prognostic factors for determining the intensity of therapy. CONCLUSIONS: Future protocols conducted by pediatric oncology groups will incorporate biological studies. The goal is to identify patients at low risk for relapse which will allow a reduction in treatment intensity and subsequent toxicity. Children at an increased risk for relapse can be selected for more intensive treatment.

Comparison between single-dose and divided-dose administration of dactinomycin and doxorubicin for patients with Wilms' tumor: a report from the National Wilms' Tumor Study Group.

PURPOSE: The National Wilms' Tumor Study (NWTS)-4 was designed to evaluate the efficacy, toxicity, and cost of administration of different regimens for the treatment of Wilms' tumor (WT). PATIENTS AND METHODS: Between August 6, 1986 and September 1, 1994, 1,687 previously untreated children less than 16 years of age with stages I to II/favorable histology (FH) or stage I/anaplastic histology WT (low-risk [LR] group) or stages III to IV/FH WT or stages I to IV/clear cell sarcoma of the kidney (high-risk [HR] group) were randomized to treatment that included vincristine and either divided-dose (standard [STD]) courses (5 days) or single-dose (pulse-intensive [PI]) treatment with dactinomycin. HR patients also received either STD courses (3 days) or PI treatment with doxorubicin. RESULTS: The 2-year relapse-free survival (RFS) rates for LR patients were 91.3% for 544 randomized to treatment with PI and 91.4% for 556 randomized to treatment with STD chemotherapy (P = .988). The 2-year RFS rates for HR patients were 87.3% for 299 randomized to treatment with PI and 90.0% for 288 randomized to treatment with STD chemotherapy (P = .865). CONCLUSION: We conclude that patients treated with PI combination chemotherapy for LR or HR WT or clear cell sarcoma of the kidney have equivalent 2-year RFS to those treated with STD regimens. PI drug administration is recommended as the new standard based on demonstrated efficacy, greater administered dose-intensity, less severe hematologic toxicity, and the requirement for fewer physician and hospital encounters.

What imaging studies are necessary to determine outcome after ureteroneocystostomy?

PURPOSE: After ureteroneocystostomy we have performed renal ultrasonography within the first 3 months to exclude hydronephrosis, voiding cystography after 3 months to exclude vesicoureteral reflux and subsequent ultrasonography to monitor the upper tracts. This study attempted to determine those patients at risk for hydronephrosis or recurrent vesicoureteral reflux. MATERIALS AND METHODS: We studied the records of patients who underwent ureteroneocystostomy in the last decade at our institutions to find the incidence and degree of preoperative and postoperative hydronephrosis and vesicoureteral reflux. Results of initial postoperative imaging were compared to radiological imaging throughout followup (mean 2.3 years). Patients with postoperative reflux were evaluated for risk factors that differentiated them from others. RESULTS: Excluding patients with neuropathic bladder or ureterocele, 167 underwent 278 ureteroneocystostomies at a mean followup of 26.5 months. Persistent vesicoureteral reflux was noted in 4 kidneys (1.4%) and contralateral reflux developed in 3 of the 48 cases (6.3%) of unilateral ureteroneocystostomy. There was no statistical difference in success rates among cross-trigonal, ureteral advancement or extravesical techniques. New onset mild hydronephrosis in 13 kidneys (4.7%) at the initial followup study (mean 1.6 months) completely resolved in 12 and remained mild in 1. No patient had progression of existing hydronephrosis and 1 had recurrent vesicoureteral reflux after initial negative cystography. Risk factors for postoperative reflux or hydronephrosis were preoperative dysfunctional voiding, preoperative hydronephrosis or scarring on sonography and postoperative urinary tract infection. None of the 88 patients without these risk factors had postoperative hydronephrosis or reflux. All patients with persistent, contralateral or recurrent reflux were selected using these criteria (p < 0.003). CONCLUSIONS: Complication rates after nontapered ureteroneocystostomy in children without neuropathic bladder are quite low. Mild postoperative hydronephrosis was not clinically significant in our patients. Children with abnormal preoperative ultrasound or dysfunctional voiding are identified as a high risk group for postoperative hydronephrosis or recurrent reflux. All other patients received little benefit from postoperative imaging, suggesting that further evaluation of this group is necessary only in the presence of a postoperative urinary tract infection.