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Saudi Journal of Kidney Diseases and Transplantation
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Table of Contents   
ORIGINAL ARTICLE  
Year : 2011  |  Volume : 22  |  Issue : 6  |  Page : 1160-1163
Kidney imaging in management of delayed febrile urinary tract infection


1 Urology and Nephrology Research Center, Kermanshah University of Medical Sciences, Iran
2 Department of Pediatric Nephrology, Tabriz Medical University, Pediatric Health and Research Center, Tabriz, Iran
3 Department of Radiology, Tabriz Medical University, Pediatric Health and Research Center, Tabriz, Iran

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Date of Web Publication8-Nov-2011
 

   Abstract 

We report a cross-sectional study performed to evaluate the imaging findings of 40 children, aged one month to five years (16.65 ± 14.97 months), who presented with protracted fever of more than 48 hours due to urinary tract infection (UTI). About 85% of the patients had positive Tc99-Dimercaptosuccinic acid (DMSA) scan and 58% had vesicoureteral reflux (VUR). Kidney sonography aided in the diagnosis and treatment in 10% of the patients. Age, sex, presence or laterality of VUR did not contribute to defective DMSA scan (pyelonephritis) (P > 0.05). Delayed diagnosis and treatment of febrile UTI is associated with a high incidence of positive findings of DMSA scan irrespective of age, sex or presence/absence of VUR. In mild VUR, the DMSA scan may be normal while in patients with moderate and severe VUR the DMSA scan is almost always abnormal. Thus, our study shows that a normal DMSA scan can help in ruling out moderate to severe forms of VUR and that cystography remains an excellent and standard tool for the diagnosis of VUR.

How to cite this article:
Sayedzadeh SA, Malaki M, Shoaran M, Nemati M. Kidney imaging in management of delayed febrile urinary tract infection. Saudi J Kidney Dis Transpl 2011;22:1160-3

How to cite this URL:
Sayedzadeh SA, Malaki M, Shoaran M, Nemati M. Kidney imaging in management of delayed febrile urinary tract infection. Saudi J Kidney Dis Transpl [serial online] 2011 [cited 2019 Nov 13];22:1160-3. Available from: http://www.sjkdt.org/text.asp?2011/22/6/1160/87224

   Introduction Top


Imaging study is one of the most important modalities used in the management of urinary tract infection (UTI) in young children. The goal of imaging studies is to provide anatomic evaluation and reveal abnormalities such as vesicoureteral reflux (VUR), obstructive uropathy, urethrocele, acute inflammation and renal scarring; all these disorders may impose significant risk for recurrent infections and long-term complications in children. Voiding cystourethrography (VCUG) and ultrasonographic studies are recommended by the American Pediatric Academy as the first step in the management of febrile UTI. [1] Because of inadequate information about the efficacy of these modalities in treatment and prognosis of UTI, [2] we aimed to evaluate the importance and significance of each of these imaging studies in children who were diagnosed as having UTI and managed with a delay of at least 48 hours. This study was carried out at the Kermanshah Imam Reza Hospital; 40 patients with primary diagnosis of upper UTI with a positive urine culture were evaluated.


   Methods and Materials Top


In this study, 40 patients aged between 45 days and 5 years were included. All the children were febrile for at least 48 hours. Fever was defined as a rectal temperature of more than 38.3°C. All of them had positive findings on urinalysis, with more than 10 white blood cells (WBCs) in one mL of uncentrifuged urine and bacteriuria defined as presence of any gram negative bacillus per high power field on oil immersion setting. The next step in evaluating the patients was to document a positive urine culture, which was defined as 50,000 colony count per one mL of urine. [3],[4],[5] The urine samples were collected by catheterization in children younger than three years and by collection of sterile mid-stream urine in more obedient older patients. For the latter group, positive culture was defined as 100,000 colony count per one mL of urine. After treatment, a second urine culture was obtained and when negative, the patients underwent VCUG and reflux, when present, was graded according to the international classification as follows: Grade I: reflux into a non-dilated ureter; Grade II: reflux into the ureter, pelvis and calyces with no dilation; Grades III, IV and V: reflux into the ureter, pelvis and calyces with mild, moderate or severe dilation or tortuosity of the ureter. [6] In another nomenclature, reflux Grades I and II were labeled as mild, Grade III as moderate and Grades IV and V as severe reflux. [7] Radionuclide scanning with Technetium99-labeled dimmercaptosuccinic acid (DMSA) was performed in the acute phase (within 14 days ) of the disease, and acute pyelonephritis was defined as either localized or diffuse photopenia with intact renal borders or diffuse decrease in uptake in an enlarged kidney.

The collected data were organized and expressed as number and percent by age and sex as well as presence of VUR and a positive DMSA scan. For qualitative parameters, chi-square test and for quantitative variables, t-independent test were used. For statistical calculations, α ≤0.05 was considered as significant.


   Results Top


Forty children in the age group of one to 60 months were studied (mean age 16.6 ± 14.97 months). Of these cases, 27 were female (67.5%) and 13 male (32.5%), all patients were admitted after at least 48 hours of fever caused by UTI. Twenty-three children (57.5%) had associated VUR, which included 14 patients (61%) with mild, seven patients (30%) with moderate and two cases (9%) with severe reflux [Table 1] and [Table 2]. The VUR was unilateral in 13 children (56% and bilateral in 10 others (44%) [Table 3].
Table 1: Correlation of presence or absence of vesicoureteral reflux and presence of positive or negative renal isotope scanning in patients with pyelonephritis.

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Table 2: Correlation of severity of vesicoureteral reflux and presence of positive or negative renal isotope scan in patients with pyelonephritis.

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Table 3: Side of presence of vesicoureteral reflux (unilateral or bilateral) in patients with positive and negative renal scan.

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Thirty-four patients (85%) had reduced uptake of tracer on Tc99-DMSA scan in the acute phase of UTI. The DMSA scan was positive in 15 out of 17 patients without reflux and 19 out of 23 with reflux. Overall, positive scan was seen in 77% (10 out of 13) of the patients with unilateral and 80% (8 out of 10) of the patients with bilateral VUR. There was no correlation between bilateral or unilateral VUR and presence of posi tive isotope renal scan. The mean age of patients with a positive scan was 18.3 ± 15.86 months.

There was no correlation between age and presence of pyelonephritis defined as positive scan (18.3 ± 15.86 months in positive group vs 8.71 ± 5 months in negative group, P was insignificant). The correlation between gender and positive scan was also statistically insignificant.


   Discussion Top


The aim of imaging in patients with UTI is to detect and manage urological abnormalities early that, improves the patient's prognosis. [8]

In our study, 33 of the 40 children (82.5%) diagnosed and treated for UTI after 48 hours of onset of fever had positive scan (pyelonephritis), while 23 out of 40 patients (57%) had VUR.

Sonography as a non-invasive technique is performed routinely in patients with UTI. This diagnostic tool helps to detect renal size and diagnose some abnormalities such as duplication ureterocele and horse shoe kidney; [9] however, it is not sensitive for the detection of pyelonephritis scar, hydronephrosis or hydroureter. [10],[11],[12],[13]

In our study, 82% of the patients were diagnosed as having pyelonephritis (by nuclear scan), and 55% had VUR. In 90% of the patients, sonography failed to show any abnormalities while in the other 10%, it contributed to our management by detecting the presence of stone and stasis in the renal pelvis.

Association of VUR in patients with pyelonephritis is higher in an episode of acute pyelonephritis and older children have a higher prevalence of associated reflux than younger children. [4]

In our study, we found the same, as the mean age of patients with pyelonephritis and VUR was higher than in those with pyelonephritis without reflux, but this difference was insignificant (P > 0.05) [Table 4].
Table 4: Mean age in patients with/without vesicoureteral reflux or pyelonephritis (P insignificant).

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Positive renal scan is seen in 51 to 90% of patients with UTI, but in patients with associated VUR, this ratio reaches 79 to 86%. [3],[4],[5] In some reports, VUR was seen in 10 of 11 patients with a positive scan while in other studies, it has been reported in 45% to as high as 90% of the patients. [14],[15],[16]

We found that the presence of VUR solely does not seem to increase the incidence of pyelonephritis (82% of +VUR vs. 88% of -VUR), although all patients with negative isotope scan had mild VUR, while all those with moderate and severe reflux had pyelonephritis (positive renal scan). This shows that in the presence of VUR, positive DMSA scan will be associated with more severe reflux.

These findings suggest that negative isotope scan can help in ruling out severe VUR. [17],[18]

Since our study was conducted in children aged below five years with delayed management of febrile UTI, the incidence of pyelonephritis (positive renal scan) reaches up to 85%. Under such circumstances, pyelonephritis will occur irrespective of age, sex and presence of unilateral or bilateral VUR.

Although positive renal scan cannot predict the existence of VUR, especially in mild form, its absence can help in ruling out severe reflux. The presence of normal and abnormal DMSA scan during an episode of pyelonephritis is so near between patients with VUR and without VUR, we cannot predict the result of cystogram but we can predict that in mild VUR, the DMSA scan will be normal while in those with moderate and severe VUR, the DMSA scan will be defective in almost all patients. This aspect needs to be studied in a larger patient population for statistical confirmation.

Sonography for the diagnosis of UTI should be considered for selected complicated cases. Cystouretrography is a valuable, standard imaging tool for planning appropriate management and prediction of prognosis in febrile UTI.


   Acknowledgment Top


We would like to thank the patients and their parents that came with us always.

 
   References Top

1.Downs SM. Technical report: urinary tract infections in febrile infants and young children. Pediatrics 1999;103:54.  Back to cited text no. 1
    
2.Dick PT, Feldman W. Routine diagnostic imaging for childhood urinary tract infections: a systematic overview. J Pediatr 1996;128:15-22  Back to cited text no. 2
    
3.Hoberman A, Wald ER, Hickey RW, et al. Oral versus initial intravenous therapy for urinary tract infections in young febrile children. Pediatrics 1999;104:79-86.  Back to cited text no. 3
    
4.Hoberman A, Wald ER, Reynolds EA, Penchan-sky L, Charron M. Pyuria and bacteriuria in urine specimens obtained by catheter from young children with fever. J Pediatr 1994;124: 513-9  Back to cited text no. 4
    
5.Hoberman A, Wald ER, Penchansky L, Reynolds EA, Young S. Enhanced urinalysis as a screening test for urinary tract infection. Pediatrics 1993;91: 1196-9.  Back to cited text no. 5
    
6.Medical versus surgical treatment of primary vesicoureteral reflux: report of the International Reflux Study Committee. Pediatrics 1981;67: 392-400.  Back to cited text no. 6
    
7.Willi U, Treves S. Radionuclide voiding cystography. Urol Radiol 1983;5:161-73.  Back to cited text no. 7
    
8.Hoberman A, Charron M, Hickey RW, Baskin M, Kearney DH, Wald ER. Imaging studies after a first febrile urinary tract infection in young children. N Engl J Med 2003;348:195-202.  Back to cited text no. 8
    
9.Practice parameter: The diagnosis, treatment, and evaluation of the initial urinary tract infection in febrile infants and young children. American Academy of Pediatrics, Committee on Quality Improvement, Subcommittee on Urinary Tract Infection. Pediatrics 1999;103:843-52.  Back to cited text no. 9
    
10.Foresman WH, Hulbert WC Jr, Rabinowitz R. Does urinary tract ultrasonography at hospitalization for acute pyelonephritis predict vesicoureteral reflux? J Urol 2001;165:2232-4.  Back to cited text no. 10
    
11.Sreenarasimhaiah V, Alon US. Uroradiologic evaluation of children with urinary tract infection: are both ultrasonography and renal cortical scintigraphy necessary? J Pediatr 1995;127:373-7.  Back to cited text no. 11
    
12.Jakobsson B, Nolstedt L, Svensson L, Soderlundh S, Berg U. 99m Technetium-dimercaptosuccinic acid scan in the diagnosis of acute pyelonephritis in children: Relation to clinical and radiological findings. Pediatr Nephrol 1992; 6:328-34.  Back to cited text no. 12
    
13.Jakobsson B, Soderlundh S, Berg U. Diagnostic significance of 99m Tc-dimercaptosuccinic acid (DMSA) scintigraphy in urinary tract infection. Arch Dis Child 1992;67:1338-42.  Back to cited text no. 13
    
14.Rushton HG, Majid M. Dimercaptosuccinic acid renal scintigraphy for the evaluation of pyelonephritis and scarring: a review of experimental and clinical studies. J Urol 1992;148:1726-32.  Back to cited text no. 14
    
15.Zaki M, Al-Mutari G, Al-Saleh Q, Ramadan DG. Febrile urinary tract infection in children: Role of 99MTc-dimercaptosuccinic acid (DM-SA) scan and other imaging techniques. Ann Saudi Med 1996;16:410-3.  Back to cited text no. 15
    
16.Melis K, Vandevivere J, Hoskens C, Vervaet A, Sand A, Van Acker KJ. Involvement of the renal parenchyma in acute urinary tract infection: the contribution of 99mTc dimercaptosuccinic acid scan. Eur J Pediatr 1992;151:536-9.  Back to cited text no. 16
    
17.Tseng MH, Lin WJ, Lo WT, Wang SR, Chu ML, Wang CC. Does a normal DMSA obviate the performance of voiding cystourethrography in evaluation of young children after their first urinary tract infection? J Pediatr 2007;150:96-99.  Back to cited text no. 17
    
18.Preda I, Jodal U, Sixt R, Stokland E, Hansson S. Normal dimercaptosuccinic acid scintigraphy makes voiding cystourethrography unnecessary after urinary tract infection. J Pediatr 2007;151: 581-4.  Back to cited text no. 18
    

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Correspondence Address:
Majid Malaki
Assistant Professor of Pediatric Nephrology, Tabriz Medical University, Pediatric Health Research Center, Post Code 5136735886, Tabriz
Iran
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PMID: 22089774

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  [Table 1], [Table 2], [Table 3], [Table 4]



 

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