This Month in Pediatric Urology

Article Outline

• Estimation of Renal Function in Children With Spinal Dysraphism
• A Proposed Algorithm for Management of Neonatal Torsion
• Urinary Metabolic Evaluation in Children With Stones
• Long-Term Functional Results of Ureterocystoplasty
• Daytime Diuresis and Urinary Frequency in Children With Incontinence
• Copyright

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Estimation of Renal Function in Children With Spinal Dysraphism 

Renal function is generally estimated by assessing the serum creatinine. However, it is recognized that serum creatinine is influenced by body muscle mass and may not reflect impairments of glomerular filtration rate (GFR) in individuals with congenital impairments. Serum cystatin C, a low molecular weight protein, may be independent of body size and overcome the limitations of serum creatinine, providing a better estimate of GFR. Abrahamsson et al (page 2407) from Goteborg, Sweden explore the use of serum cystatin C in children and adolescents with spina bifida, known to have limitations of body mass index and muscle mass which can impair the reliability of serum creatinine. They prospectively compared serum cystatin C to ⁵¹Cr edetic acid clearance (CEC), which is considered the gold standard for assessing GFR, in 65 children. Cystatin C was within a normal reference range for all children although 10 had reduced function based on CEC. When cystatin C was used to calculate GFR, values were below 2 standard deviations in 10 cases, of which only 4 correlated with a CEC below 2 standard deviations and 6 had a normal CEC. Cystatin C may be more accurate than serum creatinine but the authors conclude slight and moderately reduced GFR may go undetected with cystatin C monitoring.

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A Proposed Algorithm for Management of Neonatal Torsion 

Kaye et al (page 2377) from New Hyde Park, New York report their experience with neonatal torsion and propose an algorithm for management. During a 14-year period 15 neonates were diagnosed with neonatal torsion within the first month of life, including 12 with in utero testicular torsion (1 bilateral) and 3 with acute testicular torsion. All cases of in utero testicular torsion resulted in infarction and 1 case of acute neonatal testicular torsion was salvaged. In 50% of the cases in utero testicular torsion was associated with a significant prenatal complication including preeclampsia, gestational diabetes and twinning. This rate is higher than other rates reported. Nine of 10 infants were delivered vaginally. There was no significant difference in side of involvement with 9 cases on the right side and 7 on the left side.

The children in the in utero testicular torsion group underwent intervention on average within 8 days of birth. No asynchronous contralateral testicular torsion was reported, although contralateral torsion was found intraoperatively in 1 neonate initially thought to have unilateral torsion. The benefit of color Doppler ultrasonography was limited because of difficulty in finding any flow within a normal neonatal testicle. The authors conclude that a neonate with in utero testicular torsion can be treated with orchiectomy and contralateral orchiopexy after age 1 month to minimize operative and postoperative complications. Emergency operative intervention is warranted for any neonate presenting with what is believed to be acute torsion although the salvage rate is low.

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Urinary Metabolic Evaluation in Children With Stones 

The incidence of urinary stone disease in children is subjectively increasing. Predicting who will have a recurrent stone could have an important role when counseling families regarding potential dietary changes, therapy and followup. DeFoor et al (page 2369) from Cincinnati, Ohio continue their investigation of pediatric stone disease and retrospectively assessed 24-hour urinary metabolites in an effort to identify risk factors that will predict recurrent stone formation. The study included children with renal or ureteral calcium stones who had at least 1, 24-hour urinary assessment after initial diagnosis. Management of each stone was individualized. No specific therapy was given after treatment other than encouraging increased urine output and restricting added salt.

A total of 148 urine samples were collected from 88 children with a single stone and 84 samples from 55 children with recurrent stones. Mean age, gender and followup were similar in both groups. Urinary calcium levels were significantly higher in children with recurrent stones. The supersaturation of calcium oxalate was also higher in recurrent stone formers but this difference was not statistically significant. Even with those differences, however, the majority of patients in both groups maintained the accepted normal reference of calcium excretion which is less than 4 mg/kg a day. The authors conclude that suggestive evidence supports the use of 24-hour urine chemistry studies to identify children at higher risk for recurrent stones. A child with an increased urine calcium level identified on a 24-hour urine collection may benefit from more aggressive dietary and pharmacological management.

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Long-Term Functional Results of Ureterocystoplasty 

Augmentation cystoplasty remains an important component of bladder rehabilitation in children with severe neurogenic and obstructive pathology. Although effective, morbidity varies with use of bowel. An alternative approach is ureterocystoplasty for children with significant hydroureteronephrosis in an effort to eliminate the metabolic consequences and long-term risk of malignancy. Johal et al (page 2373) from London, United Kingdom review a single surgeon's experience with ureterocystoplasty in 17 patients. Average patient age at the time of treatment was 6 years and mean followup was 4.5 years. The ipsilateral kidney was preserved in 9 cases and nephrectomy was performed in 7. Followup assessment 6 months after augmentation included urodynamics, renal sonography and serum studies. Mean preoperative bladder capacity improved 130% and there was a 70% reduction in end filling pressure. No further surgery was required in 13 children and 2 required anticholinergic medication. Ileocystoplasty was performed in 4 children with progressive upper tract changes due to a high pressure, poorly compliant bladder. The authors demonstrate in a select group of children that ureterocystoplasty results in improved bladder capacity and compliance for several years.

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Daytime Diuresis and Urinary Frequency in Children With Incontinence 

Urinary incontinence is one of the most common problems seen in an outpatient pediatric practice. Using diaries, Mahler et al (page 2384) from Aarhus, Denmark explore the relationship among voiding frequency, bladder capacity, diuresis and fluid intake in children with daytime incontinence and compare them to healthy controls with no history of voiding dysfunction. A total of 219 children with incontinence and 87 healthy controls 14 to 15 years old completed the diary. The populations were subdivided into voiding patterns of decreased frequency (less than 3 voids a day), normal (3 to 7 voids a day) and increased frequency (greater than 7 voids a day). A significant difference was noted in diuresis and frequency in children with incontinence but age adjusted capacity was similar in the normal frequency and increased frequency subgroups. There was a positive correlation of voiding frequency and diuresis in the control group with no correlation between age adjusted capacity in any of the subgroups. Diuresis was directly influenced by fluid intake in both cohorts. The authors conclude that fluid intake and diuresis influence voiding frequency in all children more so than bladder capacity, and suggest that these factors be considered when assessing voiding diaries.