Sonographic assessment of renal length in the first year of life: the problem of "spurious nephromegaly".

PURPOSE: Interest in the potential diagnostic or prognostic implications of nephromegaly as evidence for compensatory renal hypertrophy has recently been emphasized in a variety of clinical settings. This project was designed to compare the results of linear and nonlinear sonographic models in the interpretation of renal size and growth during the first year of life. MATERIALS AND METHODS: We identified all renal and abdominal ultrasound examinations that were performed between March 1994 and October 1997 in full-term infants under age 1 year during which (1) both renal lengths were measured and (2) both kidneys appeared anatomically normal. Using three different computerized algorithms based on published standards for sonographic renal length in relation to age, we calculated z-scores for the renal lengths and compared the results of the three methods: in method A the standards at birth, 1 week, 4 months, 8 months, and 1 year were all used; in method B the 1-week standard was omitted; in method C the standards at 1 week, 4 months, and 8 months were omitted. RESULTS: We evaluated 1,234 renal measurements in 617 patients (293 boys, 324 girls; mean age 0.24 year). Compared with method A, z-scores were significantly increased when either method B or C was used (P < 0. 0001). The mean increment in z-score was + 0.433 for method B and + 1.135 for method C. The prevalence of "nephromegaly" (z > + 2) was significantly increased when subannual standards were omitted (P < 0. 0001): using method A, 20 (1.6 %) kidneys were large for age compared with 74 (6.0 %) using method B, and 214 (17.3 %) using method C. All kidneys that were large for age based on method A were also large for age using both methods B and C. The rate of false-positive diagnosis of nephromegaly was 73 % (54/74 kidneys) with method B and 91 % (194/214 kidneys) with method C. CONCLUSIONS: Although the use of multiple subannual standards for renal length in infants less than 1 year of age is time consuming and mathematically more complicated, omission of these standards results in a statistically significant increase in the frequency of "spurious" nephromegaly. LEARNING OBJECTIVES: Precise application of published standards is important in the interpretation of sonographic measurements of renal length. Omission of the subannual standards for renal length in children who are less than 1 year of age can result in an incorrect impression of nephromegaly.

Single-system ureteroceles in infants and children: imaging features.

PURPOSE: The purpose of this manuscript is to describe the clinical and imaging findings in children who have single-system ureteroceles. MATERIALS AND METHODS: We reviewed the urology records and imaging studies in 32 consecutive infants and children who were diagnosed in our department with single-system ureteroceles. RESULTS: There were 35 ureteroceles in the 32 patients-- 29 were unilateral (14 right-sided, 15 left-sided) and 3 were bilateral. Twenty-five patients were boys (78 %) and 7 girls. Mean age at presentation was 0.7 years (0-9.2 years). Prenatally detected hydronephrosis or cystic renal dysplasia was the most common presentation (24 patients). Four presented with urinary infection, 2 with abdominal mass, 1 had myelomeningocele, and 1 had hypospadias. Three patients also had multiple non-urologic, congenital anomalies. Thirty-three ureteroceles were intravesical, and 2 were ectopic to the bladder neck. Twenty-four ureteroceles were associated with ipsilateral hydroureteronephrosis and 10 with ipsilateral multicystic dysplastic kidney. One patient had a normal ipsilateral kidney and a contralateral multicystic dysplastic kidney. The ureterocele was identified on at least one imaging study in each patient. Sixteen ureteroceles (47%) everted at VCUG, mimicking paraureteral diverticula. Other variations included ureterocele prolapse and inadvertent ureterocele catheterization (1 each). CONCLUSIONS: Single-system ureterocele is an important, although uncommon cause of hydronephrosis and renal dysplasia in infants and children. Single-system ureterocele is distinguished clinically from the more common duplex-system ureterocele by its frequent occurrence in boys and its association with multicystic dysplastic kidney. Because these ureteroceles are frequently small and have a propensity to evert at VCUG, they can be mistaken for paraureteral diverticula.

The impact of vesicoureteral reflux on contralateral renal length in infants with multicystic dysplastic kidney.

PURPOSE: The purpose of our study was to determine the influence of vesicoureteral reflux (VUR) on contralateral renal length in neonates and young infants with unilateral multicystic dysplastic kidney (MCDK). MATERIAL AND METHODS: We reviewed the imaging findings in 48 term neonates and infants (27 boys; 21 girls) who had unilateral MCDK (mean age at diagnosis 0.09 years; range 0-0.64 years). Each had renal ultrasonography (RUS), renal scintigraphy, and voiding cystourethrography before 1 year of age. The diagnosis of MCDK was based on characteristic imaging findings (i. e., an echogenic, cystic kidney at RUS that did not function at scintigraphy). None had contralateral hydronephrosis or cysts. We calculated an age-corrected z-score for contralateral renal length (at RUS) in each patient based on published standards. We examined the effects of gender, ipsilateral or contralateral VUR, and age at RUS on the contralateral renal length using multifactor ANOVA. RESULTS: Nine patients (19 %) had VUR into the contralateral kidney. The refluxing kidneys were significantly shorter (renal length: median 5.1 cm, mean 5.07 cm; z-score: median - 0.43, mean - 0.58) than the nonrefluxing kidneys (renal length: median 6.2 cm, mean 6. 08 cm; z-score: median 1.03, mean 1.04; P < 0.001). The contralateral kidney was more than 1 SD longer than the mean for age in none of the 9 patients with VUR on that side. By comparison, the contralateral kidney was more than 1 SD longer than the mean for age in 21 (54 %) of 39 patients with no VUR on that side, and more than 2 SD longer than the mean in 5 (13 %). CONCLUSION: VUR into the kidney contralateral to a MCDK is associated with smaller size of that kidney during the first year of life.

Ureteral compression and obstruction by spine rods.

We present a case of extrinsic compression of a ureter by spinal fixation hardware and adjacent fibrosis that resulted in progressive obstructive hydronephrosis, loss of renal function, and, ultimately, nephrectomy.

Vesicoureteral reflux in older children: concordance of US and voiding cystourethrographic findings.

PURPOSE: To determine if a negative renal sonogram is reliably predictive of the absence of vesicoureteral reflux at voiding cystourethrography (VCUG) in children aged 5 years or older. MATERIALS AND METHODS: Imaging studies in 70 children aged 5 years or older who underwent renal ultrasound (US) and VCUG on the same day were reviewed. These children had initially undergone evaluation because of a urinary tract infection. RESULTS: Five of 70 children had abnormal sonograms; two (40%) of the five had reflux at VCUG. One had mild pelvicalyceal dilatation, and one had a small kidney. The other three (without reflux) had a pelvic kidney, a calyceal diverticulum, or a renal stone. Of 65 children with a negative sonogram, 19 (29%) had reflux at VCUG; 46 (71%) did not. Altogether, of the 70 children, 21 had reflux, 19 (90%) of whom had no sonographic abnormality. CONCLUSION: Children with abnormal screening renal sonograms often have vesicoureteral reflux, but a normal sonogram does not reliably exclude the condition even in children aged 5 years or older. Therefore, VCUG must be performed even in older children, regardless of US findings, if clinical decisions are influenced by documentation of the presence of VUR.

Wilms tumor imaging: patient costs and protocol compliance.

PURPOSE: To evaluate the patient costs for imaging and compliance with imaging protocols in pediatric patients in the National Wilms Tumor Study (NWTS) IV. MATERIALS AND METHODS: The medical and imaging records of 60 patients (28 male, 32 female; aged 3 days to 12.6 years) in NWTS IV were reviewed. Initial imaging and follow-up imaging were evaluated separately. Three levels of follow-up compliance were evaluated. RESULTS: The total patient cost for imaging was $442,180: $94,212 for initial and $347,968 for follow-up studies. Many areas of potential cost savings were identified. Protocol compliance was variable. Seventy-five percent of patients underwent studies in full compliance with the initial protocol requirements. For follow-up, compliance was 0%-80% for different studies at different compliance levels. For no study was compliance 100%. CONCLUSION: Imaging costs in pediatric patients with Wilms tumor are substantial. Protocol compliance was not optimal.

Uroradiologic emergencies in infants and children.

Selected topics are discussed that represent common reasons for performing emergency uroradiologic examinations in infants and children, including urinary tract infection, hematuria, urinary retention, intermittent ureteropelvic junction obstruction, spontaneous perforation of the augmented urinary bladder, and urethral trauma. Common complications of voiding cystourethrography in children are also discussed.

Lower urinary tract abnormalities in children with multicystic dysplastic kidney.

PURPOSE: To determine the nature and frequency of associated structural abnormalities of the lower urinary tract in children with multicystic dysplastic kidney. MATERIALS AND METHODS: The authors reviewed imaging findings from studies in 59 children with unilateral multicystic dysplastic kidney. All patients had undergone renal ultrasonography (US), renal scintigraphy, and voiding cystourethrography. The diagnosis was based on characteristic imaging findings (echogenic, cystic kidney at US that did not function at scintigraphy). RESULTS: Nineteen (32%) patients had one or more abnormalities of the lower urinary tract. Vesicoureteral reflux was most common (15 patients). Reflux occurred into the contralateral ureter in 12 patients and the ipsilateral atretic ureter in five (two had bilateral reflux). Four patients had ectopic ureters: Three cases were ipsilateral and inserted into the prostatic urethra (two cases, both with reflux) or into the seminal vesicle (one case); one case was contralateral and inserted into the bladder neck. Four patients had an ipsilateral obstructed single-system ureterocele. Four patients had bladder diverticula. Other abnormalities included hypospadias, opacification of a small utricle (not in the patient with hypospadias), ejaculatory duct reflux, internal urachal sinus, and lipomeningocele with a neurogenic bladder. CONCLUSION: Abnormalities of the lower urinary tract are common in children with unilateral multicystic dysplastic kidney. Voiding cystourethrography should be performed routinely in this population.

Mild renal pelvic dilatation is not predictive of vesicoureteral reflux in children.

OBJECTIVE: To determine if mild renal pelvic dilatation at renal ultrasound (RUS) is a reliable sign of vesicoureteral reflux (VUR) at voiding cystourethrogram (VCUG) in children. MATERIALS AND METHODS: All patients less than 10 years of age who had RUS and VCUG on the same day during a 2-year period were identified in a computerized database. The appearance of the collecting system of each kidney was classified into two groups: group 0 - no dilatation (

Latex allergy in patients with myelomeningocele presenting for imaging studies of the urinary tract.

OBJECTIVE: We prospectively surveyed patients with myelomeningocele who presented in our department over a 3-month period to determine the frequency of latex allergy in this population. MATERIALS AND METHODS: A questionnaire assessed history of allergy to latex and attitudes toward and use or avoidance of latex-containing products in both medical and nonmedical environments. RESULTS: Surveys were completed by 118 patients (56 boys, 62 girls; mean age 10.4 years, range 0.6-30.9 years). Seventy-two (61%) had heard of latex allergy and 25 (21%) reported being allergic to latex. Most allergic patients were performing intermittent self-catheterization (92%) and tended to be slightly older (mean age 12.7 years) than those not reporting allergy (mean age 9.8 years). Although most reactions were limited to rashes and mucosal irritation, two patients experienced anaphylaxis with severe respiratory symptoms or hypotension or both. No reactions had occurred in the Department of Radiology. While 84% of patients with previous allergic reactions reported trying to avoid further exposure to latex in the hospital, at home, or in school, only 14% of non-allergic patients took any special precautions. CONCLUSION: Allergy to latex is common in patients with myelomeningocele who are examined in our department. We have developed a policy designed to prevent exposure of such patients to latex during imaging studies.

Growth of the solitary kidney after nephrectomy in children with unilateral Wilms' tumor.

OBJECTIVE: We reviewed the length of the solitary kidney from all ultrasound examinations in 34 children who had undergone unilateral nephrectomy for Wilms' tumor, in order to determine the frequency of renal hypertrophy in this population. Standard sonographic criteria for nephromegaly were used. MATERIALS AND METHODS: We generated a z-score for each measurement of the renal length, using an interpolated computer model based on published standards for sonographic renal length in relation to age. A retrospective age- and gender-matched control population of children with sonographically normal paired kidneys was generated from a departmental computerized pediatric uroradiology data base, and their ipsilateral renal lengths were compared with those of the study patients. Sonographic renal hypertrophy (SRH) was defined by two or more consecutive measurements of the renal length exceeding two standard deviations longer than the mean for the patient's age, with no later normal measurement. RESULTS: Seventeen (50 %) of the 34 patients developed SRH. The latest measurements of the solitary kidney in the patients were significantly longer (mean z = 2.210) than in their controls (mean z = 0.040), even among the patients who did not develop SRH (patients' mean z = 1.000, controls' mean z = -0. 210, p < 0.001). Because boys had slightly longer kidneys than girls (both patients and controls), SRH was also noted more often in boys. The frequency of SRH was unrelated to age at nephrectomy, side of the solitary kidney, tumor stage, chemotherapy regimen, or treatment with radiation therapy. CONCLUSIONS: Although renal growth in a solitary kidney is accelerated in most children after unilateral nephrectomy for Wilms' tumor, the sonographic length of the solitary kidney will be larger than normal in only half of the patients.

Sonographic measurement of renal length in children: does the position of the patient matter?

PURPOSE: This prospective study was designed to determine the effect of patient positioning on sonographic measurements of renal length in children. Materials and methods. Two dedicated pediatric ultrasonographers (observers A and B) measured the sonographic lengths of 48 kidneys in 25 children (two had unilateral renal agenesis). Each observer obtained the two "longest possible" measurements for each kidney with the patient in three positions: supine, contralateral decubitus, and prone. Patients with myelomeningocele, hydronephrosis, and renal cysts were excluded. RESULTS: Both examiners obtained significantly higher values for renal lengths with the children lying supine (observer A P

Incidence of vesicoureteral reflux in children with unilateral renal agenesis.

We retrospectively reviewed 51 pediatric cases of unilateral renal agenesis to determine the incidence of contralateral vesicoureteral reflux. Initial diagnosis of unilateral renal agenesis was made by evaluation of associated congenital abnormality in 21 patients, evaluation of prenatally detected abnormality in 11, evaluation of urinary tract infection in 7, sibling screening in 3, hypertension in 2 and other methods in 7. A voiding cystourethrogram was obtained in 44 cases. Indications for the study included urinary tract infection in 11 patients, hydronephrosis in 18 and screening in 15. Overall, vesicoureteral reflux occurred in 19 of the 51 patients (37%). The highest incidence of contralateral reflux was in those with a prenatal abnormality with or without hydronephrosis (77%) although 5 of 15 patients (33%) who underwent a screening voiding cystourethrogram had reflux. Mean followup was 50 months. Of the patients with vesicoureteral reflux reimplantation was performed in 9, reflux spontaneously resolved in 3 and reflux persisted in 7. There is a high incidence of vesicoureteral reflux in children with unilateral renal agenesis and a voiding cystourethrogram is recommended even in the absence of hydronephrosis or urinary tract infection. Although 50% of children in our series underwent surgical intervention, a period of nonoperative observation is warranted.

Colonic strictures in children with cystic fibrosis.

PURPOSE: To determine the radiographic, clinical, surgical, and histologic findings in children with cystic fibrosis who develop strictures of the colon. MATERIALS AND METHODS: Ten children (five boys, five girls; age range, 2.5-9.0 years; mean age, 5.5 years), who were treated at the practices of the authors, were retrospectively identified and their medical records reviewed. RESULTS: Radiographic manifestations of the colonic disease included mucosal irregularity and spiculation with nodular thickening of the colonic wall and loss of normal colonic haustration. Luminal narrowing involved long segments of the colon. Longitudinal shortening of the colon was also a prominent feature. The decrease in caliber of the bowel ranged from mild narrowing to complete occlusion of the lumen. Histologic examination revealed severe submucosal fibrosis and fatty infiltration with transmural extension of the fibrosis to involve the serosa in some cases. Unlike in Crohn disease, however, acute inflammatory changes were minimal or absent. CONCLUSION: Colonic stricture in children with cystic fibrosis is due to irreversible and frequently progressive narrowing of the colonic lumen.

Benign cystitis in children mimicking rhabdomyosarcoma.

Seventeen (13 male, 4 female) patients, aged 13 months to 13 years, with benign cystitis had imaging findings that mimicked those of rhabdomyosarcoma. Our experience indicates that in the child with hematuria, dysuria, and frequency plus cystographic or sonographic demonstration of a bladder with reduced capacity and circumferential wall thickening or sonographic findings of isoechoic bladder wall thickening (focal, multifocal or circumferential distribution), intact mucosa, and bullous lesions should strongly suggest inflammation and not malignancy. When an inflammatory lesion is suspected, follow-up imaging should be performed in 2 weeks, which if normal will preclude biopsy.

Hydronephrosis in the neonate and young infant: current concepts.

Asymptomatic neonates with urological abnormalities that were discovered antenatally or during screening sonography in the neonatal period differ in a number of important ways from those presenting later with overt clinical signs and symptoms of urological disease. The accumulated experience with these neonates over the past decade has led to important advances in our understanding of the epidemiology, diagnosis, and management of congenital disorders of the urinary tract.

Bladder diverticula in children.

PURPOSE: The frequency, number, and underlying associations of bladder diverticula were studied in a pediatric population. MATERIALS AND METHODS: Eighty-five children with bladder diverticula (31 girls and 54 boys) were retrospectively identified in a pediatric genitourinary data base of 5,084 children. RESULTS: Primary bladder diverticula were seen in 20 children with vesicoureteral reflux and 14 children without reflux. Fifty-one of the 85 children (60%) had associated neurogenic dysfunction of the bladder (n = 26), outlet obstruction (n = 14), or a syndrome (n = 9) or were postoperative (n = 2). A single child of the 26 with multiple bladder diverticula had no associated condition. CONCLUSION: In this population, bladder diverticula were found in 1.7% of the children. The presence of more than one diverticulum on a side was usually associated with neurogenic dysfunction of the bladder, bladder outlet obstruction, or syndromes such as Williams, Menkes, prune-belly, or Ehlers-Danlos type 9 syndromes.

Splenic enlargement in neonates during ECMO.

PURPOSE: To determine whether hepatosplenomegaly was a reproducible finding in seven neonates who were being treated with extracorporeal membrane oxygenation (ECMO) for respiratory failure. MATERIALS AND METHODS: The authors measured splenic and hepatic dimensions with ultrasound (US) at the time ECMO was initiated and then every 24-48 hours until decannulation. Splenic volume and the index of hepatic size were calculated by using published formulas. RESULTS: Splenic volume increased in all seven patients from 8.3 cm3 +/- 1.7 to 16.4 cm3 +/- 4.4 (P < or = .001). Hepatic size did not change markedly. CONCLUSION: Hemolysis, leukopenia, and platelet activation occur during ECMO. Rapid splenic enlargement may be secondary to sequestration of red cells, platelets, and other hematologic elements that have been damaged in the ECMO circuit. Since the liver does not also increase in size, the splenic enlargement is unlikely to be the result of passive congestion.