Harmonic versus conventional ultrasound imaging of the urinary tract in children

Background:Harmonic imaging (HI) is a relatively new US method. Its usefulness in children has yet to be determined. Objective: To evaluate the value of HI in urinary tract imaging of infants and children. Materials and methods: The bladder and kidneys of 29 unselected patients, aged 2 months to 12.8 years (mean, 6.8 years), were examined from ventral and dorsal approaches using conventional (= fundamental) imaging (FI) (6.5 and 3.4 MHz) and HI (3.3 MHz). In addition to global image quality, visualization of bladder wall, retrovesical space, renal contrast to liver/spleen, the pelvicalyceal systems, and the difference between cortex and medulla were assessed. Parameters were rated by two independent examiners and statistical analysis was performed. Results: There were significant differences between the three imaging settings for all parameters studied (P<0.003). With the dorsal approach, HI was superior to FI for all parameters analysed (P<0.05). Using the ventral approach, a significant improvement of imaging with HI was found for the bladder and the renal pelvis (P<0.02). Conclusions: HI is a useful additional tool for imaging the urinary tract in children of all ages. The method particularly improves visualization of the bladder and the kidney from a dorsal approach.     

Non-contrast thin-section helical CT of urinary tract calculi in children

BACKGROUND: Non-contrast thin-section helical CT has gained acceptance for the diagnosis of urinary tract calculi in adults, but experience with the technique in children is limited. PURPOSE: To evaluate the utility of non-contrast thin section helical CT for the diagnosis of urinary tract calculi in children. MATERIALS AND METHODS: Radiology databases at three pediatric institutions were searched to identify all pediatric patients evaluated by "renal stone" protocol CT scans (no oral or intravenous contrast, scans covering the entire urinary tract obtained in helical mode with narrow collimation (< 5 mm)). CT scans were reviewed for the primary finding of urinary tract calculi, for secondary signs of acute urinary tract obstruction and for evidence of alternative diagnoses. Medical records were reviewed to determine clinical presentation and to confirm the eventual diagnosis. RESULTS: One hundred thirty-seven scans of 113 children (mean age: 11.2 years) were studied. Thirty-eight of 94 examinations (40%) performed on 82 children for acute pain and/or hematuria showed ureteral calculi. Alternative diagnoses were suggested by CT on 16 scans (17%). Twenty-eight scans were performed on 10 asymptomatic children with known calculus disease confirming renal stone burden on 21 scans (75%) and persistent ureteral calculi on 6 scans (21%). Upper tract calculi were demonstrated on 10 of 15 scans (67%) performed to evaluate for calculi in patients with known non-calculus genitourinary tract abnormalities. CONCLUSIONS: Non-contrast thin section helical CT is a useful method to diagnose urinary tract calculi in children. Radiation dose in this retrospective study may exceed the lowest possible radiation dose for diagnostic accuracy. Further research is needed to optimize CT imaging parameters, while maintaining diagnostic accuracy and minimizing radiation dose.     

The sonographically thickened wall of the upper urinary tract system: correlation with other imaging methods

Background. Sonographically detected, upper urinary tract wall thickening (UUTWT) was reported to occur in urinary tract infection, urinary tract stone disease, rejection after renal transplantation and vesico-ureteral reflux (VUR). A possible association with obstruction can be hypothesized. Objective. The assessment of a potential relationship of UUTWT with VUR or obstruction in patients without one of the above-mentioned conditions. Materials and methods. We analyzed 38 patients (74 upper urinary tracts) with at least unilateral UUTWT and concomitant imaging studies such as voiding cystourethrography (VCU), intravenous urography (IVU) and diuretic renography (DR). Results. At sonography 49 urinary tracts showed UUTWT. In 33, ipsilateral VUR could be demonstrated at VCU, 11 revealed obstruction at IVU and/or DR, and 4 showed non-obstructive pelvicalyceal dilatation at IVU and DR. In one patient, all imaging studies were normal. The positive predictive value of UUTWT for the presence of VUR was 67.4 % and for obstruction it was 22.5 %. Altogether, UUTWT indicated pathology in 98 % of urinary tracts. Conclusion. After exclusion of urinary tract infection, urinary stone disease and prior renal transplantation, the most common associated findings in UUTWT are VUR and obstruction. Therefore, VCU seems to be justified in all cases of UUTWT. Nonrefluxing systems should be further evaluated with DR and/or IVU for exclusion of obstruction. Received: 10 June 1996 Accepted: 18 January 1997     

Supine versus prone positioning for ultrasound evaluation of postnatal urinary tract dilation in children

Background

Ultrasound (US) is used in the initial evaluation and surveillance of urinary tract dilation in children. Urinary tract dilation is diagnosed in 1–2% of all pregnancies during routine prenatal sonography with technological advances in US imaging. Urinary tract dilation classification systems, including the 2014 multidisciplinary consensus, assess anterior–posterior renal pelvic diameter and calyceal dilation. There is no consensus regarding optimal patient positioning — supine versus prone — during US assessment of urinary tract dilation.

Objective

We performed this study to determine whether there is a significant difference in the measurement of the anterior–posterior renal pelvic diameter, presence of calyceal dilation, or resulting urinary tract dilation consensus score obtained between supine and prone positions.

Materials and methods

Two raters retrospectively reviewed renal bladder US exams of children with urinary tract dilation of one or both kidneys. We included technically adequate US examinations of orthotopic kidneys that were imaged in both supine and prone positions; we excluded children with renal anomalies or prior surgery. Anterior–posterior renal pelvic diameter measurements as well as central and peripheral calyceal dilation were documented in both supine and prone positions. A postnatal urinary tract dilation consensus score was assigned to each kidney based only on these features.

Results

Urinary tract dilation in either the supine or prone position was performed in 146 kidneys (69 right, 77 left) in 89 children. Median age was 0.26 years (interquartile ratio [IQR] 0.08–0.61 years). Female-to-male ratio was 1:3 (21/89). The interclass correlations of the anterior–posterior renal pelvic diameter were 0.88 and 0.87 in the supine and prone positions, respectively, without significant differences (P=0.1). When comparing all kidneys together, the mean anterior–posterior renal pelvic diameter was 7.1 mm (95% confidence interval [CI] 6.4–7.8) in supine and 7.9 (95% CI 7.1–8.7) in prone, with a mean difference between the measurements of 0.83 mm (95% CI 0.3–1.4; P=0.16). Central calyceal and peripheral calyceal dilation were more commonly found in the prone position versus the supine position in both kidneys. Central calyceal dilation was observed in 15 cases in the prone but not in the supine position. In one kidney, it was seen only in the supine but not in the prone position. Overall the urinary tract dilation score differed between positions in 10.3% (15/146) of cases, most of them (14/15) with a higher score in prone compared to the supine position.

Conclusion

Scanning in prone position tends to more frequently show calyceal dilation and a greater size of the anterior–posterior renal pelvic diameter, resulting in higher urinary tract dilation classification scores, with almost perfect interobserver agreement.

     

Melamine-contaminated milk products induced urinary tract calculi in children

Background  Melamine is an industrial chemical used primarily as plastics stabilizer and fire retardant. On September 11, 2008, melamine-contaminated milk products were reported to be responsible for urinary tract calculi in infants and children in China. This study aimed to investigate the prevalence, lesions, risk factors, clinical features, and management of children fed with the melamine-contaminated milk products. Methods  A total of 15 577 infants and children fed with the milk products were screened at our hospital. Ultrasonography was performed in all the infants and children. For those found with urinary tract calculion ultrasonography, urnalysis was done. Among them, 846 with detailed data screened from September 17 to 25 were enrolled for further analysis in this study. They were divided into calculus group (326 children) and non-calculus group (520 children) according to the results of ultrasonography. They included 429 boys and 417 girls, aged from 1 month to 5 years (median, 18 months). Their clinical and laboratory data, ultrasonograms, and treatment results were analyzed. Results  Of the 15 577 children screened, 562 (3.61%) had urinary tract calculi. The rate was closely related to the melamine concentration in patients fed with formula. In 846 children with detailed data enrolled in this analysis, weight and head circumference Z scores in the calculus group were lower than those in the non-calculus group (P=0.048, P=0.046). Long duration of formula feeding, high melamine contained formula, and minimal water intake were the risk factors for calculi (P<0.05, respectively). Of 326 children with calculi, 281 had small calculiless than 0.5 cm in diameter, 227 had multiple calculi, and 34 had urinary tract distention. Moreover, diffuse renal lesions, renal failure and ascites were noted in 4, 3 and 2 patients, respectively. After 1-month treatment with sodium bicarbonate and Chinese traditional medicine, calculi disappeared in 49 of 54 outpatients. In 41 inpatients, 5 had calculi removed operatively and 36 had calculi minimized. Conclusions  Melamine-contaminated milk products induced urinary tract calculi, which have a good response to conservative therapy. Long-term follow-up of infants and children fed with melamine-contaminated milk products is required, and food safety should be supervised increasingly for the health of children.     

RARE-MR-urography in the diagnosis of upper urinary tract abnormalities in children

RARE-MR-urography (RapidAcquisition withRelaxationEnhancement) is a fast MR imaging technique (6.4 s/acquisition) that selectively depicts fluid by heavy T2-weighting. From 9/1989 to 11/1990, RARE-MR urograms were prospectively evaluated in the diagnosis of upper urinary tract abnormalities in 55 children. The method is performed in several planes and combined with a coronal, T1-weighted spin-echo sequence. Forty out of 42 kidneys with dilated renal pelvis, and 21 out of 24 dilated ureters were identified, only the mildly dilated ones were missed. Even in non-functioning kidneys the urinary tract was clearly depicted by RARE-MR-urography. However, no differentiation could be made with this technique between vesicoureteral reflux and non-refluxing dilatation of ureter and/or renal pelvis. All 19 pelviureteric obstructions and all eight renal duplications with a dilated segment were identified. RARE-MR-urography is a new tool for diagnosing urinary tract abnormalities in children without having to employ ionizing radiation, contrast media, or general anesthesia. A dilated urinary tract can be shown in one image displaying the entire urinary system, similar to excretory urography. The technique is presently not able to provide the information of voiding cystourethrography or renal scintigraphy, nor is it as easy to perform as ultrasound. However, in certain cases it may replace excretory urography.     

Imaging in urinary tract infection.

The relationship of vesicoureteric reflex (VUR) and renal scarring was studied in 94 children (188 kidneys) with proved urinary tract infection in a district general hospital. There were 61 girls and 33 boys, with nine girls and 17 boys aged less than 1 year, 31 girls and nine boys aged between 1 and 5 years, the remaining 28 children were over 5 years of age. All children had a micturating cystourethrogram and a 99mTc (technetium) dimercaptosuccinic acid (DMSA) scan. Forty two of the 188 kidneys were scarred and 70 of the kidneys had VUR. Only 37.1% of the kidneys with reflux were scarred but 61.9% of the scarred kidneys had VUR. In children of less than 1 year, 48% of kidneys with VUR were scarred whereas 70.6% of scarred kidneys had reflux. In children between 1 and 5 years of age only 36.4% of kidneys with VUR were scarred but 63.2% of scarred kidneys had VUR. There is good correlation between the detection of a scarred kidney on DMSA and the presence of vesicoureteric reflux. However the detection of reflux particularly in children over 1 year of age shows poor correlation with renal scarring. This suggests that the primary imaging in children over 1 year of age presenting with a urinary tract infection should be of the kidney: a cystogram should be performed only if the DMSA scan is abnormal.     

Imaging of pyelonephritis

Objective. Accurate diagnosis of pyelonephritis using clinical and laboratory parameters is often difficult, especially in children. The main aims of this prospective study were to compare the value of different imaging techniques [renal sonography, cortical scintigraphy with technetium-99m dimercaptosuccinic acid (^99mTc DMSA) and computed tomography (CT)] in detecting renal involvement in acute urinary tract infections and to determine the sensitivity of DMSA scans for permanent renal scars 6 months later. Materials and methods. Between February 1992 and January 1993, 55 children admitted to our pediatric unit with febrile symptomatic urinary tract infections were eligible for analysis. Ultrasonography (US), DMSA scanning and micturating cystourethrography were performed in every case. Only 18 children underwent CT. A second DMSA scan was performed in 48 children a mean of 7.5 months after the first. Results. US abnormalities were found in 25 children (45 %). The first DMSA scan showed a parenchymal aspect suggestive of pyelonephritis in 51 patients (93 %). Among the 18 patients studied by CT, 14 had abnormalities. Normal US findings did not rule out renal parenchymal involvement. Scintigraphy appeared to be more sensitive than CT for renal involvement. The frequency and degree of initial renal parenchymal damage seemed to correlate with vesicoureteral reflux, but the most severe initial parenchymal defects were not associated with marked clinical or laboratory manifestations. Repeat DMSA scans, performed on 45 kidneys with abnormalities at the first examination, showed resolution in 19, improvement in 16, persistence in 8 and deterioration in 2. The prevalence of vesicoureteral reflux was not higher in patients with renal scarring on the second DMSA scan than in patients whose scans showed an improvement. Conclusion. DMSA scans should be considered as a reference in the detection and follow-up of renal scarring associated with acute urinary tract infection as this technique is more sensitive than US and CT, the latter being unsuitable because it entails radiation exposure and sedation of patients. Received: 9 February 1996 Accepted: 14 February 1996     

Renal function 16 to 26 years after the first urinary tract infection in childhood

OBJECTIVE: To evaluate renal function in a population-based cohort with urographic renal scarring after childhood urinary tract infection (UTI). DESIGN: Follow-up investigation 16 to 26 years after the first recognized UTI. SETTING: Outpatient university clinic for children with UTI serving the local area. PATIENTS: From the original cohort of 1221 consecutive children with first UTI diagnosed during 1970 to 1979, 57 (41 females and 16 males; mean age, 24.5 years) of 68 with nonobstructive renal scarring participated as well as 51 (38 females and 13 males; mean age, 24.9 years) matched subjects without scarring. MAIN OUTCOME MEASURE: Glomerular filtration rate (GFR) measured by chromium 51-EDTA clearance, expressed as milliliters per minute per 1.73 square meters. RESULTS: Median GFR was 99 in both those with and without renal scarring. In patients with unilateral scarring, the total GFR remained unchanged over the years whereas the individual GFR of the scarred kidneys declined significantly from 46 to 39. In 7 patients with bilateral scarring, the GFR declined from 94 to 84 (P = .14); compared with those with unilateral scarring, the GFR was significantly lower at follow-up (P = .007). Median urinary albumin-creatinine ratio was 1.2 and 0.6 mg/mmol in those with scarring and those without, respectively (P = .30). CONCLUSIONS: The GFR 2 decades after the first recognized UTI in childhood was well preserved. However, a significant reduction of individual renal GFR in the unilaterally scarred kidneys indicates that further follow-up is required. Although there were few patients with bilateral scarring, a more serious prognosis can be expected among them.     

Serum vitamin A and β-carotene concentrations and renal scarring in urinary tract infections

OBJECTIVE—To evaluate the role of vitamin A on renal scarring in recurrent urinary tract infections (UTIs).
DESIGN—Twenty three children with UTIs and renal scarring (mean (SD) age 7.3 (3.9) years) and 91 children without renal scarring (6.4 (3.4) years) were studied. All the children had serum vitamin A and β-carotene measurements and nutritional evaluation. Renal scarring was assessed by technetium-99m dimercaptosuccinic acid (^99mTc DMSA) scanning. Nutritional status of all the patients was within normal limits and not different between the groups.
RESULTS—Mean (SD) serum vitamin A and β-carotene concentrations were not significantly different between the patients with and without renal scarring (vitamin A 53.2 (22.6)/46.8 (17.0) µg/dl and β-carotene 232.3 (201.3)/272.4 (86.0) µg/dl respectively). However, when the patients with renal scarring and with greater than 10% difference among the DMSA uptakes of their kidneys (11 cases) were evaluated, a significant negative correlation was determined between the serum vitamin A concentrations and the magnitude of the difference in uptakes of each kidney. The same relation was not true for serum β-carotene concentrations.
CONCLUSION—This study demonstrated a relation between serum vitamin A concentrations and magnitude of hypoactivity in ^99mTc DMSA scanning in kidneys with advanced scarring.

     

Combined static-dynamic MR urography for the simultaneous evaluation of morphology and function in urinary tract obstruction

Objective. A new approach, combined static-dynamic MR urography is evaluated to determine its potential utility for the functional-morphological diagnosis of paediatric urinary tract obstruction. In this initial investigation we sought to evaluate the procedure by imaging the urinary tract of piglets. Materials and methods. Twenty-nine healthy piglets were studied with MR urography (MRU), ^{99 m}Tc-MAG3 diuretic renal scintigraphy (DRS), ultrasound (US) and excretory urography (EU). The functional and morphological findings were compared. For MRU we combined a respiration-triggered 3D-IR-TSE sequence and a dynamic 2D-FFE sequence after Gd-DTPA injection. Results. MRU depicted the complete urinary tract with superior image quality compared to EU. Calculation of time-intensity curves from the dynamic sequence permitted determination of single kidney function from parenchymal ROIs and urinary excretion using the whole kidney ROI. MRU and DRS showed significant agreement in the assessment of both single kidney function and urinary excretion. Disturbances of urinary drainage were generally caused by an overfilled bladder. Conclusions. Combined static-dynamic MRU is well suited for the depiction of the complete urinary tract and for the determination of individual kidney function and urinary excretion in the piglet. Received: 21 February 2000 Accepted: 14 March 2000     

Ultrasound screening for renal and urinary tract anomalies in healthy infants

BACKGROUND: Nearly 30% of childhood cases of chronic renal failure in Japan are attributed to congenital anomalies of the kidney and urinary tract (CAKUT), and the number is increasing. Urine screening at school facilitates early diagnosis and treatment of glomerulonephritis, but early screening for anomalies is currently not in practice. The authors evaluated the value of early abdominal ultrasonography screening in 1-month-old infants. METHODS: The following characteristics of kidneys were assessed: presence versus absence, size, symmetry of size, position, separation of the central echo complex (CEC), abnormal echogenicity, and other abnormal findings. The bladder and ureter were checked for abnormalities in bladder shape and wall, as well as retrovesical ureteral dilation. Criteria for abnormalities included kidney length of or=60 mm; a difference in length of left and right kidneys of 10 mm or more; and CEC separation of Society for Fetal Urology (SFU) grade 2 or higher. RESULTS: Beginning in April 1994 and continuing until September 2001, screening of 5700 1-month-old infants yielded 198 positive cases (3.5%) of CAKUT. Most frequent was abnormal CEC separation (approximately 60% of all abnormalities), followed by abnormal renal size or size asymmetry (30%). Further investigation yielded a specific diagnosis in 32 cases (0.6%) of all subjects. Most prevalent was obstructive uropathy (15 cases); 8 children underwent surgery. Small kidneys and vesicoureteral reflux were next in frequency. CONCLUSIONS: Ultrasonograpy was effective for early detection of renal and urinary tract anomalies. Ultrasound screening in early infancy may permit early treatment, that can prevent renal dysfunction.     

儿童泌尿系统梗阻畸形合并上尿路结石的术中内镜治疗

目的 探讨儿童泌尿系统梗阻畸形外科手术中联合内镜治疗儿童泌尿系统梗阻畸形合并上尿路结石的安全性和有效性.方法 回顾分析我院小儿外科2010年1月1日至2013年8月31日收治的17例儿童泌尿系统梗阻畸形合并上尿路结石的患儿临床资料.男13例,女4例,年龄3～12岁,平均年龄5.9岁,左侧14例,右侧3例.肾积水、UPJO合并肾脏结石11例,输尿管膀胱连接处狭窄合并肾盂内结石3例,输尿管膀胱连接处狭窄合并输尿管末端结石者2例,输尿管膀胱连接处狭窄合并肾输尿管多处结石1例,结石直径4～12 mm.结果 11例肾积水、UPJO(肾盂输尿管连接处狭窄)患儿均顺利行离断式肾盂输尿管成形术,术中均行经肾盂输尿管镜或膀胱镜检查肾盂内各盏,10例患儿成功取出结石,1例术中未见找到结石,术后辅助行体外震波碎石治疗(ESWL).6例输尿管膀胱连接处狭窄(UVJO)患儿均顺利行膀胱外输尿管膀胱再植术,术中4例顺利行输尿管硬镜检查术,2例顺利行输尿管软镜检查术,结石顺利取出4例,2例术中检查未能发现结石.结论 对于儿童泌尿系统梗阻畸形合并上尿路结石,在梗阻畸形外科手术治疗的同时联合内镜治疗上尿路结石是理想、安全、有效的.     

Predictive factors associated with significant urinary tract abnormalities in infants with pyelonephritis.

BACKGROUND: Major urinary tract abnormalities are detected in 20 to 40% of infants with acute pyelonephritis (APN). Early detection of structural defects is essential for protecting the kidneys from reinfection and subsequent scarring. The purpose of this study was to investigate whether any factors present during the acute phase of infection could predict the presence of existing significant urinary tract abnormalities in infants. METHODS: A prospective study of 180 infants, aged 1 to 24 months, with APN was conducted. Blood and urine samples were collected. Renal ultrasound (US) was performed within 0 to 6 days from admission. Final diagnosis of the urinary tract anatomy was elucidated using the results of two or more radiologic imaging studies. RESULTS: Risk factors for the presence of significant urinary tract abnormalities in infants were pathogens other than Escherichia coli in urine [relative risk (RR) 3.4, 95% confidence interval (CI) 2.2 to 5.3; P = 0.001], positive blood culture (RR 2.3, 95% CI 1.3 to 4.0; P = 0.039), young age (1 to 6 months) (RR 2.2, 95% CI 1.3 to 3.9; P = 0.004), lack of papG adhesin genes of E. coli in urine (RR 2.1, 95% CI 1.2 to 3.9; P = 0.016) and abnormal renal US (RR 2.0, 95% CI 1.2 to 3.4; P = 0.008). CONCLUSIONS: Infants 1 to 6 months of age with APN caused by bacteria other than E. coli or by papG-negative E. coli strain, positive blood culture and abnormal renal US carry an increased risk for significant urinary tract abnormalities and need enforced follow-up.     

The role of DMSA scans in evaluation of the correlation between urinary tract infection, vesicoureteric reflux, and renal scarring

The correlation between urinary tract infection (UTI), vesicoureteric reflux (VUR) and renal scarring was studied in 89 patients (177 renal units; 1 solitary kidney) during the period 1997–2000. There were 63 males and 26 females; ages ranged from neonates to 14 years. UTI was diagnosed on the basis of a positive urine culture, VUR was diagnosed and graded by micturating cystourethrogram (MCU), and renal scarring was assessed by technetium 99 m Tc-dimercaptosuccinic acid (DMSA) scan. Ultrasonography (US) was done to evaluate renal tract dilatation and other structural abnormalities. A follow up DMSA scan was performed approximately 6 months after the initial scan. VUR was present in 106 of the 171 renal units in which it was studied and absent in 65 units. The majority of the VUR was grade V. Renal scars were seen in 90 of 177 renal units at presentation and in 72 of the 163 renal units studied at follow-up. Some information was lacking in 31 patients; hence, the correlation between UTI, VUR, and renal scarring was done in 58 patients. The majority of the suspected scars at presentation were not seen at follow-up, but most of the established scars persisted. Only 2 renal units showed scars for the first time on follow-up. On US, approximately 50% of normal kidneys showed either suspicious or established scars on DMSA scan, and patients with bilateral abnormality on US showed renal scars. Renal scars were seen in 15 of 23 children without VUR, 17 of 18 with unilateral VUR, and 16 of 17 with bilateral VUR. Thus, there is a cause-and-effect relationship between UTI and renal scarring that is made worse by VUR. DMSA scans have been shown to be the most reliable method of assessing renal scarring, and an abnormal US scan showing upper-tract dilatation or a structural abnormality may have a predictive value in the detection of renal scarring. Accepted: 18 April 2001     

Uroradiology in the fetus and newborn: diagnosis and follow-up of congenital obstruction of the urinary tract

Abnormalities of the fetal urinary tract, most commonly hydronephrosis of differing causes, can be detected by ultrasound (US). Prenatal measurements of the kidney can help to predict the postnatal outcome of hydronephrosis. About 20 % of abnormalities evident in utero are not present after birth. After delivery, various imaging procedures, particularly US and voiding cystourethrography may be necessary to evaluate prenatally diagnosed abnormalities. Pyelectasis may be due to obstruction and this may be assessed by sonography during diuresis, urography or diuretic renography. Renography can also evaluate global and split function of the kidneys. ¹²³I-hippurate and ^{99 m}Tc-MAG3 are superior to ^{99 m}Tc-DTPA, but there is no ’gold standard' technique available to assess obstruction. The majority of cases of hydronephrosis, even those which appear to be due to obstruction, can be treated conservatively without deterioration of renal function. Primary megaureter is the second most common cause of obstructive hydronephrosis in the newborn. The diagnostic procedures are similar if the dilated ureter persists unchanged and the infant is asymptomatic. Newborns with antenatally detected renal abnormalities frequently have associated vesicoureteric reflux. Received: 6 February 1996 Accepted: 26 November 1997     

Ultrasonography in urinary tract infection in infancy

In a prospective study 77 infants (35 boys) with a mean age of 5.23 months were studied to determine the value of sonography for detection of renal parenchymal involvement in urinary tract infection (UTI). Sonography was performed during UTI and about one month later. UTI was classified as upper and lower UTI according to the clinical and laboratory findings; radiological investigations (voiding cystoureterography = MCU) were performed in all infants. 40 infants were classified to have upper UTI. There was a high sensitivity (80%) and specificity (97%) for detection of renal involvement by sonography. Incidence for vesicoureteral reflux (VUR) was significantly higher in infants with repeated pathological findings on sonography. In contrast, no VUR was detected on MCU in all 12 infants with normal findings in both sonographic examinations. Yet, sonography without catheterization could not detect VUR in all infants with radiologically confirmed reflux. Our results show, that sonography is of definite value in infants with UTI, but cannot replace radiological work up.     

Pathogenesis of urinary tract infection: an update

PURPOSE OF REVIEW: Urinary tract infection is the second most common bacterial infection in children. It may cause renal scarring leading to secondary hypertension and chronic kidney disease. Recent information has greatly improved our understanding of the pathogenesis of urinary tract infection and renal scarring. RECENT FINDINGS: Urothelium, an anatomical barrier for innate immune responses, expresses toll-like receptors with the capacity to recognize pathogen-associated molecular patterns. Engagement of toll-like receptors can lead to uroepithelial cell activation and production of inflammatory mediators. These include complement proteins, other bactericidal peptides, cytokines, chemokines, defensins and adhesion molecules. The resulting inflammatory infiltrate serves to aid bacterial clearance but can also lead to renal damage. Furthermore, interactions between urinary proteins, such as Tamm-Horsfall protein, and TLR-4 add to the complexity of this defense system. Interindividual variability in cellular response may in part be responsible for variable clinical outcomes. Polymorphisms in a number of candidate genes in this host defense mechanism may be involved in determining those patients who are susceptible to recurrent infections and renal scarring following urinary tract infection. SUMMARY: Further understanding of the basic molecular mechanisms of urinary tract infection and translating these bench data to the bedside holds the promise of improving diagnosis and therapeutic strategies of treating urinary tract infection and preventing recurrence and renal scarring.     

Primary and acquired renal scarring in boys and girls with urinary tract infection

OBJECTIVES: To determine when pyelonephritic renal scarring was detected in children with urinary tract infection (UTI) and characterize those with primary and acquired scarring, respectively. STUDY DESIGN: A population-based cohort of 1221 children (989 girls and 232 boys) with first recognized symptomatic UTI, aged 0 to 15 years, were diagnosed and followed up prospectively at a single children's hospital; 652 had febrile UTI. Seven hundred fifty-three were evaluated by urography. Renal scarring was classified as primary or acquired, the latter without signs of scarring at the first investigation. To evaluate the frequency of recurrent UTI in those with acquired scarring, a comparison with group-matched children without scarring was performed. RESULTS: A total of 74 children without obstruction had renal scarring (acquired in 40). Primary scarring was found in 18 of 21 (86%) of the boys and 16 of 53 (30%) of the girls (P <.001). The majority of boys with scarring had dilated reflux (67%) in contrast to girls (23%). Recurrent UTI was rare in boys, whereas girls with acquired scarring had significantly more febrile recurrences than girls without scarring. CONCLUSIONS: Most boys had primary, probably congenital, reflux-associated renal damage, whereas most girls had acquired scarring related to recurrences of febrile UTI.