This Month in Pediatric Urology

Article Outline

• Predictive Factors for Resolution of Congenital High Grade Vesicoureteral Reflux
• Scar Formation in Children With First Febrile Urinary Tract Infection
• Clinicopathological Findings of Transarterial Chemoembolization for Wilms Tumor
• Bonn Risk Index to Assess the Risk of Urinary Calcium Oxalate Crystallization
• Copyright

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Predictive Factors for Resolution of Congenital High Grade Vesicoureteral Reflux 

High grade vesicoureteral reflux (VUR) in infants is a distinct entity compared to high grade VUR detected later in childhood because of its greater rate of spontaneous resolution or improvement and relatively frequent congenital renal function abnormalities. Sjostrom et al (page 1177) from Goteborg, Sweden report an observational study of 80 male and 35 female infants diagnosed at a median age of 2.7 months after a urinary tract infection (UTI) in 72% and after an abnormal prenatal ultrasound in 26%. Reflux was grade III in 16% of cases, grade IV in 45% and grade V in 39%. Patients were evaluated with video cystometry, renal scintigraphy and chromium edetic acid clearance scan. Median followup was 36 months. VUR resolved spontaneously in 30 cases and was downgraded to I to II in 14 at a mean of 27 months. Breakthrough UTIs occurred in 54 infants with increasing frequency in higher grades of VUR. General and focal renal abnormalities developed in 72 and 26 patients, respectively. Bladder dysfunction in 48 infants included large capacity with incomplete emptying in 36, overactive bladder in 12 and uncertain dysfunction in 24. Multivariate analysis revealed that renal functional abnormalities, bladder dysfunction and breakthrough UTIs were strong independent negative predictive factors of spontaneous resolution or downgrading of VUR. A child with no bladder dysfunction, breakthrough UTI and renal abnormality had a 91% probability of VUR resolution before age 3 years compared to only a 7% probability if all 3 negative predictors were present.

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Scar Formation in Children With First Febrile Urinary Tract Infection 

Dimercaptosuccinic acid scintigraphy (DMSA) provides a unique opportunity to follow the progression of renal damage and functional loss from initial insult of acute pyelonephritis to subsequent development of irreversible renal scarring. Oh et al (page 1146) from Seoul, Korea analyzed clinical factors that may predict the formation of acute photon defects (APDs) and ultimate scar formation in 89 girls and 138 boys with first time febrile UTI. Reflux in 199 kidneys (140 patients) was grade I in 22 renal units, grade II in 53, grade III in 60, grade IV in 50 and grade V in 14. All patients were evaluated with ultrasound and DMSA scan within 7 days of the UTI and again after 6 months, and voiding cystourethogram at a median of 4 weeks after the UTI. Multivariate analysis revealed that therapeutic delay time and presence of VUR were predictive factors for formation of APD with odds ratio of 2.32 and 1.35. Multivariate analysis indicated that therapeutic delay time, presence of VUR and increased absolute neutrophil count were predictive factors for ultimate scar formation with odds ratios of 10.12, 2.36 and 1.042, respectively. A positive linear association was seen between increasing VUR grade and APD (p=0.001), whereas no association was found between VUR grade and scar formation (p=0.279) on linear association test. The authors conclude that although the presence of VUR was the most important host risk factor for APD and renal scarring, DMSA scans were the most important imaging modality for diagnosis and prediction of renal scarring.

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Clinicopathological Findings of Transarterial Chemoembolization for Wilms Tumor 

Transcatheter arterial chemoembolization (TACE) with anticancer drugs mixed with embolics has been used for nonoperable hepatocellular carcinoma and other hypervascular malignant tumors. Li et al (page 1138) from Guangzhou, China report the histological features of resected tumors from patients who underwent TACE, including tumor cell apoptosis, necrosis, interstitial fibrosis, lymphocyte infiltration and expression of pro-apoptotic proteins. They compared the findings in these patients with a group who underwent primary surgical resection. All patients received 6 cycles of postoperative systemic chemotherapy. Tumor volume was calculated before and after TACE. Embolization was performed with the patient under ketamine general anesthesia via a transfemoral approach. Chemotherapeutic agents used were doxorubicin and vincristine, the main artery supplying the tumor was embolized with gelatin sponge particles and chemotherapy infusion, and surgery was scheduled a mean of 14 days later. Histological examination of the specimens in the TACE group showed higher degrees of tumor necrosis, interstitial fibrosis and lymphocyte compared with the control group. The mitotic index was lower and the apoptotic index was higher in the TACE group compared to controls. Significantly more tumor cells expressed Bax in the TACE group than in the control group but there was no difference in Bcl-2 expression between the groups. There was no correlation between the percentage of tumors cells expressing p53 and the apoptotic index or degree of tumor differentiation within each group of patients. The authors conclude that TACE may achieve its therapeutic effect on Wilms tumors by inducing tumor cell necrosis and degeneration, boosting tumor interstitial fibrous tissue hyperplasia, promoting lymphocyte invasion and inhibiting tumor cell growth while inducing tumor cell apoptosis. However, TACE was not compared in this study with preoperative chemotherapy alone, raising the question of whether this approach is superior.

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Bonn Risk Index to Assess the Risk of Urinary Calcium Oxalate Crystallization 

The incidence of stone disease is increasing and there is a relatively high incidence of identifiable metabolic disturbances in the pediatric population. The majority of stones are composed of calcium oxalate (CaOx) and insight into the pathophysiology of stone formation in these at risk children can aid in determining optimal preventive management. Porowski et al (page 1157) from Bialystok, Poland used a modified approach to determine the Bonn Risk Index (BRI) to assess the risk of urinary CaOx stone formation. This index, determined by the ratio of urinary calcium ion concentration-to-the amount of titrated ammonium oxalate required to induce crystallization of CaOx in a urine sample, allows for determination of the risk of CaOx stone formation in vivo. By controlling the titration process using a special computer software program, the authors automatically calculated the BRI in 190 children from 1.5, 2.0 and 3.0 ml urine samples, and compared those values to the BRI obtained from standard 200 ml samples. Abnormally elevated BRI values were found in 30 patients based on the standard 200 ml method as well as the 3 ml and 2 ml approach, whereas the 1.5 ml approach identified 27. An additional 6 patients were found to be at risk using the 3 ml and 2 ml approaches but not with the 200 ml method, representing possible false-positive tests. Method comparison according to standard laboratory analysis revealed that the results of the 2 ml and 3 ml approach agreed sufficiently with those obtained from the established 200 ml method. Limitations of this approach include the current lack of commercial availability and the requirement that the test be performed either on a fresh urine sample or a sample stored and transported at 4C. Advantages include the small volume of urine required for testing, simplicity and efficiency of the methodology, and low cost of performing the analysis. The authors conclude that their modified approach to the BRI is a reliable method for risk assessment of calcium oxalate stone formation.