Urinary tract infection in infants and children evaluated by ultrasound

Fifty-nine pediatric patients with urinary tract infection (UTI) underwent renal ultrasonography, excretory urography, and voiding cystourethrography. The imaging procedures were analyzed retrospectively to determine their relative effectiveness in detecting abnormalities that might predispose the patient to UTI. Voiding cystourethrography provided valuable information, particularly the presence or absence of vesicoureteral reflux, that could not be obtained from the other procedures. Excretory urography was less specific than ultrasonography in the majority of patients, with the exception of those who had renal scarring. The authors recommended ultrasonography as the initial imaging procedure in the evaluation of children with UTI. When the sonogram is normal, excretory urography is not considered necessary, but voiding cystourethrography is thought to be essential. If sonography is abnormal, excretory urography and/or other follow-up studies are indicated.     

Imaging of children with urinary tract infection: a tailored approach

We reviewed the initial imaging studies of 283 children with urinary tract infection in order to decide on the most effective approach. A voiding cystogram was performed in all, complemented by either urography (147 patients), ultrasonography (65), or both (71 patients). In the latter group there was good correlation between sonographic and urographic findings, except for a more accurate delineation of renal scars and anomalies on urography, all in children with vesicoureteral reflux and/or abnormal sonograms. From these data we derived two imaging sequences tailored to the clinical circumstances: cystography as the initial study in ambulatory patients after infection has subsided, and sonography followed by cystography in children hospitalised with severe infection. The upper tracts are studied by ultrasonography and/or urography in patients with significant vesicoureteral reflex or an abnormal sonogram. Both these sequences reduce radiation by omitting the urogram in roughly half of the patients.     

Ureteral dilatation in children with febrile urinary tract infection or bacteriuria

Little information is available on the relationship between urinary infection in children and infants, with or without vesicoureteral reflux, and dilatation of the urinary tract. The purpose of this study was to determine the effects of infection and reflux on the diameter of the ureter at excretory urography in children with acute, febrile urinary tract infections and in infants with bacteriuria found at screening. Standardized measurements of ureteral diameter were obtained for 79 children (2 months to 6 years old) with urinary tract infections and for 45 infants with bacteriuria. Patients with urinary tract obstruction or malformations were excluded. Seventy-one children with febrile urinary tract infection had ureteral visualization that allowed measurements. Ureteral diameter in this group was significantly wider than in a reference group, and 42 children (59%) had ureteral diameters that were more than 2 standard deviations above the normal mean. Ureteral diameter at excretory urography increased with increasing grades of reflux, but dilatation occurred also in the absence of reflux. Twenty-two of the 45 infants in the group with bacteriuria had sufficient ureteral visualization for measurements. The ureters in this group were wider than in the reference group, and eight infants had ureteral diameters that were more than 2 standard deviations above the normal mean. We conclude that ureteral dilatation is a common effect of acute urinary tract infection and bacteriuria in children.     

Imaging and the first urinary infection in children. Respective role of each test during the initial evaluation apropos of 122 cases

122 pediatric patients with a first urinary tract infection underwent renal ultrasonography (US) and voiding cystourethrography (VCUG) to evaluate the usefulness of this association. The US was always the first examination undertaken, its sensitivity seems to be very good in detecting renal abnormalities. The major finding on the VCUG was the vesico-ureteral reflux: 25% of cases. When the sonogram and the VCUG are normal, 60% of cases, excretory urography is not considered necessary.     

Voiding cystourethrography: the initial radiologic study in children with urinary tract infection

The order in which children with urinary tract infection should undergo voiding cystourethrography (VCUG), excretory urography (EU), and/or renal ultrasonography (US) is not standardized. To determine a logical sequence of study, we performed VCUG and then either US or EU on 389 consecutive children with urinary tract infections. Thirty-seven percent (133/358) of the children were found to have reflux; of these, 22.5% (30/133) had an abnormal excretory urogram. No correlation was found between either the age of the child and the degree of reflux or the age of the child and the percentage of children with abnormal excretory urograms. Since normal EU or US results do not exclude significant reflux, VCUG is recommended as the preferred initial screening examination in children with urinary tract infection.     

Vesicoureteral reflux in adults.

Vesicoureteral reflux was detected in 200 adults seen in a 4 year period. In group 1 (no history of urinary tract infection and negative urine cultures), all patients had abnormalities on excretory urograms that were suggestive of reflux. In patients with a history of recurrent urinary tract infection (groups 2 and 3), the excretory urograms showed an abnormality in 79 per cent of those with negative cultures and in 83 per cent of those with positive cultures. Thus, reflux should be suspected in patients with a history of recurrent urinary tract infection even if infection cannot be documented with urine culture. Urographic evidence of renal parenchymal scarring, ureteral dilatation, or mucosal striations should also suggest the possibility of vesicoureteral reflux even when the patient may have no urinary tract symptoms. Voiding cystourethrography should be performed in all adults with these findings to exclude the possibility of vesicoureteral reflux.     

Renal growth retardation in children: sign suggestive of vesicoureteral reflux?

Of 141 children undergoing surgery for vesicoureteral reflux detected by voiding cystourethrography, preoperative excretory urography demonstrated signs suggestive of vesicoureteral reflux in 154 (67.5%) of 228 refluxing ureter. In 48 refluxing ureters (21%) renal growth retardation was the only sign; the latter was appreciated by applying the index described by Hodson, that is, the ratio of bipolar parenchymal thickness to total renal length. It was concluded that it is important to systematically calculate this simple index from every child's excretory urogram.     

The coexistence of ureteropelvic junction obstruction and reflux

Since ureteropelvic junction obstruction is the most common upper urinary tract problem in children, and vesicoureteral reflux the most common lower tract problem, it is not surprising that these entities sometimes coexist in the same child. Over a 10 year period this uncommon phenomenon has been noted 21 times (in about 2,800 children with reflux and 200 children with ureteropelvic junction obstruction). Significant ureteropelvic junction obstruction in association with mild reflux can mimic severe reflux, but the operation needed is not reimplantation but pyeloplasty. Conversely, when significant ureteropelvic junction obstruction coexists with significant reflux, both operations may be necessary, but the order in which they are done (pyeloplasty first) seems to be crucial. Voiding cystography with appropriate postvoid drainage films, excretory urography, often with a catheter draining the bladder to prevent reflux, and provocative diuretic excretory urography and/or renography can determine that ureteropelvic junction obstruction does coexist and quantitate the severity of each problem.     

Prediction of vesico-ureteral reflux in children from intravenous urography films.

Intravenous urography and voiding urethrocystography were performed on 255 children with urinary tract infection. Eighty-six (34%) of these children had some kind of abnormality of the urinary tract. Vesico-ureteral reflux was observed to 96 ureters (19%) in 69 children (27%). The prediction of vesico-ureteral reflux by two radiologists from urography films only gave 46 (48%) and 51 (53%) false negative results respectively. In cases of clinically important reflux (III--V degrees), however, the rate of false negative predictions was 0/18 and 1/18 (6%) respectively. The rate for false positive predictions were 45/413 (11%) for both radiologists. In view of the number of pathological findings in this series i.v. urography is recommended as a routine in children undergoing urological work-up after their first urinary tract infection. As the clinically important vesico-ureteral reflux seems to be predictable from urography films alone, voiding urethrocystography seems not to be justified in children with negative i.v. urography, and can be postponed and carried out later if the urinary tract infection recurs.     

Urinary tract infections in children: renal ultrasound evaluation

Ultrasound may replace urography in screening pediatric patients with uncomplicated urinary tract infections but without vesicoureteral reflux. A child undergoing a first radiographic evaluation for urinary tract infection is initially examined by voiding cystourethrography. If reflux is present, urography is performed. If no reflux is present, the kidneys are evaluated by real-time ultrasound; urography may also be performed if the ultrasound examination is abnormal, equivocal, or inadequate. A total of 192 patients was evaluated with this protocol; 146 (76%) had no reflux and therefore were examined with ultrasound. One patient was found to have hydronephrosis and underwent surgical correction. This group of patients was compared with a similar group of 223 patients without reflux who were evaluated by urography prior to the institution of the ultrasound protocol; there was no significant difference between the two groups in upper urinary tract findings that influenced patient management.     

Sonography vs. excretory urography in acute flank pain

A prospective study compared the diagnostic accuracy of sonography and excretory urography in determining the cause of acute flank pain in 61 patients. Forty-one patients had urinary tract stone disease. Of these, five had nonobstructing renal stones and 36 had obstructing stones. A correct diagnosis was made by urography in 85% and by sonography in 66%. Small stones at the ureterovesical junction were more accurately diagnosed by sonography (79%) than by urography (68%). In all the patients where sonography failed to detect the offending stone, the stone was calcified and evident on the plain radiographs. There were no false-positive diagnoses in the patients clinically judged to have passed a renal stone (nine patients) or whose pain was arising outside of the urinary tract (five patients). Neither sonography (17%) nor urography (50%) was accurate in diagnosing acute pyelonephritis in the six patients with this diagnosis. Although sonography is not as accurate overall as urography in acute flank pain, it is a viable alternative in those with recurrent renal colic due to stone disease and in the pregnant patient.     

Funktionelle Störungen des unteren Harntrakts im Kindesalter

Functional disorders of the lower urinary tract as well as vesicoureteral reflux involved in the disease complex of urinary tract infection/permanent renal parenchymal damage can be considered predisposing or risk factors. Two main forms can be distinguished, i.e., unstable bladder and dysfunctional voiding, while transitional forms between the two exist. Functional disorders of the lower urinary tract obstruct spontaneous resolution of vesicoureteral reflux. They are found in about 50% of cases in all children with urinary tract infection and are associated with an increased risk of developing renal parenchymal scars. They are observed during the newborn period up to school age. In the first few months of life, particularly boys with bilateral high-grade reflux and congenital renal parenchymal damage are affected. At later ages girls are also affected, but in this age group bladder instability predominates. Incontinence as the leading clinical symptom appears in approximately 70% of all cases and is closely correlated with chronic constipation. Imaging procedures in addition to urodynamic methods are of decisive importance for diagnosis and treatment, but noninvasive approaches such as sonography should be given preference.     

Caliceal clubbing and adjacent parenchymal scarring (always reflux nephropathy?) as a cause of end-stage renal failure

Various clinical and laboratory aspects in 15 kidney transplanted patients with urographic evidence of caliceal clubbing and adjacent parenchymal scarring in their native kidneys are reported. These lesions were found in 16 per cent of our series of kidney transplantations; below 35 years of age it was the second most frequent disease. In 9 of these patients severe vesicoureteral reflux had been demonstrated. In the remaining 6 patients reflux nephropathy was only a tentative diagnosis based on a striking similarity in the radiographs and in several clinical findings. Nine patients had symptoms (mainly related to urinary tract infection) from 1 to 17 years before diagnosis/urography, in 5 as early as the first year of life. Recurrent urinary tract infection and renal impairment were the most frequent disorders leading to the diagnosis. Replacement therapy was initiated at an average age of 32.7 years. Following renal transplantation urinary tract infection was documented in 37 per cent of patients whether the patient had been bilaterally nephrectomized or not.     

Urinary tract infection in children. A reappraisal of its radiologic investigation

In a prospective study, 100 children with either an acute or a previous history of urinary tract infection were investigated by intravenous urography, micturition cystourethrography, and ultrasonography. The results from the three diagnostic modalities were compared: The urinary tracts in 59 patients were normal, and revealed some abnormality in 41. Ultrasonography proved to be superior to intravenous urography in outlining renal contours and in detecting subtle cortical changes secondary to urinary tract infection (such as slight increases in cortical thickness and edema or cortical scarring). The mucosa of the renal pelvis and bladder was more easily assessed by ultrasound than by intravenous urography. Both modalities were "equally" accurate in detecting important congenital malformations of the urinary tract. Ultrasound failed to detect 24 of 28 ureters demonstrating reflux on voiding cystourethrography. We propose that carefully performed abdominal ultrasonography can replace intravenous urography in the initial investigation of urinary tract infection in children. It should be done in association with a radiographic or radionuclide voiding cystogram. Intravenous urography would then become a complementary examination for abnormal or problematic patients.     

Radiographic evaluation of children with urinary tract infections

Any child with urinary tract infection needs a radiologic work-up to determine his or her potential risk for sustaining renal damage. VCUG, either fluoroscopic or isotopic, should always be performed. If the infection responds to treatment and the VCUG is normal, ultrasonography should be performed. However, when the VCUG demonstrates reflux, radionuclide scan or, less preferably, excretory urography is indicated to assess renal parenchymal damage and function. When a urinary tract infection does not respond to treatment, ultrasonography or CT scan should be obtained to check for renal or perirenal abscess. If the findings are normal, medical treatment to control the infection is indicated. Further evaluation of the urinary tract may be temporarily delayed. In an infant with urinary tract infection and sepsis, renal ultrasonography is indicated. If the sonogram is normal, VCUG can be delayed until the infant responds to medical treatment. If ultrasonography is abnormal, VCUG and radionuclide scan such as 99mtechnetium DTPA with furosemide to evaluate gross morphology and function should be obtained. Complicated medical problems, such as urinary tract infection in combination with a history of intravenous drug abuse or with findings of fever and a mass, deserve immediate evaluation with ultrasonography or CT scan. A patient with fever of unknown origin and normal urine culture should have a radionuclide scan using gallium67 citrate or indium111-tagged leukocytes, both of which can demonstrate an extrarenal or unsuspected intrarenal site of infection. A variety of imaging modalities are available today for investigating urinary tract infections in the pediatric patient. Used intelligently, singly or in combination, these examinations provide information for the clinical evaluation as well as short-and long-term management of infections, their causes and complication, and their effect on renal function.     

Distribution of renal scars and intrarenal reflux in children with a past history of urinary tract infection

The distribution of renal scars in children with vesicoureteral reflux (VUR) and a past history of urinary tract infection was studied to see whether a correlation existed between renal scarring and intrarenal reflux. In 37 children with one or more scars in one or both kidneys, scarring was significantly more frequent in the polar areas than in the lateral area. In 7 children with intrarenal reflux (IRR), the distribution of IRR was almost identical with that of renal scarring. When children with marked VUR (grade IV-V) were analyzed separately, a uniform distribution of scars was found. It was concluded that fused papillae, which normally are most frequent in the polar area, are a prerequisite for the development of IRR/renal scars.     

Potential impact of pediatric MR urography on the imaging algorithm in patients with a functional single kidney

OBJECTIVE: The purpose of this study was to evaluate the potential of MR urography in the assessment of children with a suspected "functional single kidney." SUBJECTS AND METHODS: Sixty patients (age range, 2.7 weeks to 15.7 years) who had been referred for assessment of a suspected functional single kidney underwent MR urography in addition to detailed sonography of the urinary tract and the currently indicated standard imaging. The results of the conventional imaging ((99m)Tc-dimer captosuccinic acid scintigraphy, voiding cystourethrography, and genitography) were compared with the results of sonography and MR urography; surgical findings served as the gold standard if available. RESULTS: Twenty-six patients had a single kidney. The other diagnoses were six contralateral multicystic dysplastic kidneys, two normal ectopic kidneys, one crossfused double system, and 25 ectopic or dysplastic renal buds. Scintigraphy detected all normal kidneys, two ectopic kidneys, and two dysplastic renal buds. Detailed sonography missed two ectopic kidneys and two orthotopic dysplastic renal buds, but one additional renal bud that could not be confirmed on other imaging techniques (accuracy, 91.7%; sensitivity, 88.2%; specificity, 96.2%) was suspected. MR urography results were correct in all patients and verified in all 13 with surgical correlation. CONCLUSION: MR urography allows a reliable assessment of renal and ureteral anatomy and of dysplastic or ectopic renal buds, even in non- or poorly functioning systems. MR urography therefore has the potential to replace the currently used excretory urography and scintigraphy. In patients with a suspected functional single kidney a detailed sonographic study and MR urography should be considered the diagnostic algorithm of choice.     

Influence of vesicoureteral reflux and urinary tract infection on renal growth in children with upper urinary tract duplication

The growth of the renal parenchyma was examined in children with duplicated outflow systems, vesicoureteral reflux (VUR), urinary tract infection (UTI) and no sign of obstruction. Ten patients with reflux occurring only in the caudal system (group A) and 4 patients with reflux both to the caudal and the apical system (group B) were studied shortly after their first UTI (study 1) and then 1.5 to 9 years later (study 2). The frequency of UTI was relatively high during the follow-up period. At urography, renal length and renal area were normal in group A in studies 1 and 2. Parenchymal thickness of the apical pole (APT/L) did not differ from normal values in any of the studies. Parenchymal thickness of the caudal pole (CPT/L) was significantly smaller than normal in both studies. There was also a significant decrease in CPT/L between study 1 and 2. UTI during the first year of life was associated with a greater reduction in CPT/L. The determination of renal length and renal area in children with a duplicated ureter, VUR and UTI, does not identify subjects at risk of developing renal growth retardation while serial determinations of parenchymal thickness appear to be an appropriate method.     

Urography and voiding cystourethrography: findings in girls with urinary tract infection

The voiding cystourethrogram and excretory urogram have been considered essential parts of the evaluation of girls with urinary tract infections. To evaluate the usefulness of these procedures, 523 examinations in girls with urinary tract infections were reviewed retrospectively. The major finding on voiding cystourethrograms was vesicoureteral reflux, occurring in 36% of the children. Of the total group, 8% had excretory urographic evidence of parenchymal scarring. Higher grades of reflux were associated with an increase in parenchymal scarring. All urethras were normal, and only one paraureteral diverticulum was identified. Bladder emptying was incomplete in 46% of the patients. Ovarian radiation doses were measured with "low-dose" and standard systems. On the basis of this study, traditional approaches to the standard workup are questioned.     

Contrast-enhanced sonography of vesicoureterorenal reflux in children: preliminary results.

OBJECTIVE: The aim of our study was to evaluate contrast-enhanced sonography as an alternative to radiographic voiding cystourethrography in the detection of vesicoureteral reflux. SUBJECTS AND METHODS: A total of 46 children, ranging in age from 3 weeks to 14 years (median: 4 years, 6 months) with 92 ureterorenal units were investigated for reflux using radiographic voiding cystourethrography and contrast-enhanced sonography in one session. After sonography of the urinary tract, the bladder was filled with saline solution via a catheter. Later, a contrast-enhancing agent was instilled and sonography was repeated. Documentation was done using S-VHS video and a laser camera. Reflux was diagnosed when microbubbles were observed in the ureter or in the renal pelvis. In addition, conventional voiding cystourethrography was performed. Patients without micturition during either sonography or radiographic examination were excluded (eight ureterorenal units). RESULTS: The findings obtained by contrast-enhanced sonography and voiding cystourethrography were concordant in 78 ureterorenal units (92.9%). No reflux was detected in 67 units (79.8%) by either method. With voiding cystourethrography as the standard of reference, the sensitivity of contrast-enhanced sonography was 91.7%; the specificity, 93.1%; and the accuracy, 92.9%. The positive predictive value was 68.8%, and the negative predictive value was 98.5%. CONCLUSION: Contrast-enhanced sonography is highly sensitive for the detection of vesicoureteral reflux. Therefore, it may reduce the number of radiographic investigations.