serious complications , such as renal scarring , hypertension , and chronic renal failure can result following a delay in diagnosis and treatment .
the prevalence of renal scarring following febrile uti has been reported as 10% to 65% .
risk factors , including sex , not being circumcised , constipation , and vesicoureteral reflux ( vur ) , increase the incidence of uti .
vur is the backflow of urine from the bladder to the ureter and , in some cases , to the pelvis and calyces .
previous studies suggest that the prevalence of vur in children ranges from 25% to 40% .
although voiding cystourethrography ( vcug ) is currently used as a reliable imaging method for diagnosing vur , it is painful and expensive and exposes the patient to radiation .
considering the side effects of vcug , the lack of vur in more than 50% of children with uti , and the spontaneous recovery from low - grade vur , researchers have sought cost - effective noninvasive markers for predicting vur .
soylu et al .   reported that fever higher than 38 and c - reactive protein ( crp ) of more than 50 mg / dl were suitable predictive markers for the presence of vur and high - grade vur , respectively . in this regard ,
the present study was conducted to determine the predictive value of clinical , laboratory , and imaging findings in the diagnosis of vur in children with their first febrile uti .
this prospective cross - sectional study examined 153 children aged 1 month to 12 years with their first diagnosed febrile uti in qazvin 's children 's hospital , qazvin , iran , in 2012 through 2013 .
this hospital is the only referral hospital for children in qazvin province that is affiliated with the qazvin university of medical sciences .
the sample size was calculated on the basis of p=58% ( sensitivity for feve r>38.5 to discriminate patients to correct groups ) , d=0.08 , =0.05 , 1-=0.95 , =0.2 , and 1- ( statistical power of study)=0.8   and by using the following equation :   consecutive sampling continued until the desired sample size was reached .
the inclusion criteria for children with febrile uti were as follows : ( 1 ) first febrile uti ; ( 2 ) having symptoms of febrile uti , such as fever , chills , vomiting , diarrhea , and irritability in infants , and fever , vomiting , abdominal and flank pain , dysuria , and frequency in children ; ( 3 ) abnormal urinalysis ( the presence of leukocyturia , a positive urinary nitrite test , etc . ) ; ( 4 ) positive urine culture ( urine culture more than 110 colonies of a single pathogen in a midstream urine sample or clean catch method or 110 colonies of a single pathogen via urinary catheterization , or presence of any number of colonies of organism in urine culture taken by suprapubic method ) ; ( 5 ) performance of renal ultrasound , dimercaptosuccinic acid ( dmsa ) renal scanning , and vcug .
children meeting the following criteria were excluded from the study : ( 1 ) using antibiotics ; ( 2 ) failing to undergo vcug ; ( 3 ) having accompanying and underlying disease , such as septicemia and immune disorders ; and ( 4 ) having structural abnormalities of the urinary system ( such as ureteropelvic junction obstruction , neurogenic bladder , etc . ) except vur .
first , the symptoms of the disease were recorded , and , before the start of antibiotic therapy , serum samples were delivered to the laboratory to test white blood cell count , neutrophil count , platelet count , erythrocyte sedimentation rate ( esr ) , and crp quantitative level .
all laboratory examinations were performed by use of standard methods in the laboratory department of qazvin children hospital .
the renal ultrasound was performed within the first 48 hours of admission , the renal vcug was performed at the end of treatment when the patients were discharged from the hospital , and the dmsa renal scan was done in the first week of admission .
the ultrasound and vcug were carried out by a radiologist , and the dmsa renal scan was performed and interpreted by a nuclear medicine specialist .
any report of hydronephrosis or hydroureteronephrosis without evidence of mechanical obstructions , such as ureteropelvic junction obstruction , ureterovesical junction obstruction , and posterior urethral valves , in the renal ultrasound , and any report of reduced uptake on the dmsa renal scan for pyelonephritic changes in the kidneys were considered as suspicious for vur . according to the results of the vcug , the patients were divided into two groups : a group with vur and a group without vur .
the severity of vur was graded according to the international study of reflux in children .
grades 1 and 2 were regarded as low - grade vur , and grades 3 , 4 , and 5 were regarded as high - grade vur . the sensitivity , specificity , positive ( ppv ) and negative predictive value ( npv ) , positive ( lrp ) and negative likelihood ratio ( lrn ) , and accuracy of the clinical , laboratory , and imaging variables for diagnosis of vur were determined .
chi - square test , exact test , t - test , and nonparametric tests ( mann - whitney test ) were applied to analyze the obtained data .
the children were included in the study after their parents agreed and signed the informed consent form .
of the 153 studied patients , the male - to - female ratio was 18:135 .
the most frequent symptoms in decreasing frequency were fever ( 100% ) , chills ( 62.7% ) , and dysuria ( 42.5% ) . the most frequently grown microorganism in the urine culture was escherichia coli ( 80.3% ) . of the 153 studied patients , vur was observed in 60 ( 39.2% ) .
comparisons of the different variables between children with and without vur and also between the low - grade and high - grade vur groups are shown in tables 1 , 2 , 3 , 4 . by use of receiver operating characteristic curve analysis , it was shown that for predicting vur in children with febrile uti , crp20 mg / dl had a sensitivity of 61% ( 95% confidence limit [ cl ] , 49 - 74 ) , specificity of 57% ( 95% cl , 46 - 67 ) , lrp of 1.43 , and accuracy of 58% .
in addition , fever38.2 had a sensitivity of 60% ( 95% cl , 47 - 72 ) , specificity of 53% ( 95% cl , 42 - 62 ) , lrp of 1.26 , and accuracy of 55.5% ( table 5 ) .
the sensitivity , specificity , lrp , and accuracy of the dmsa renal scan for predicting vur were 63% ( 95% cl , 51 - 75 ) , 96% ( 95% cl , 91 - 99 ) , 14.7 , and 79.5% , respectively . also , those of the renal ultrasound were 30% ( 95% cl , 18 - 41 ) , 96% ( 95% cl , 85 - 97 ) , 3.4 , and 60.5% , respectively .
the multivariate logistic regression analysis revealed significant positive correlations between fever>38.2 and dmsa renal scan and vur , and also between esr , positive urinary nitrite test , hyaline cast , and ultrasound and high - grade vur ( table 6 ) .
this study showed that the best predictive markers for the presence of vur in children with their first febrile uti are fever>38.2 and dmsa renal scan .
in addition , for high - grade vur , esr , positive urinary nitrite test , hyaline cast , and ultrasound were the best predictive markers .
given than only 25% to 40% of children with uti have vur and that vcug is invasive and expensive and exposes the gonads to radiation , researchers have looked for noninvasive markers for predicting vur to avoid unnecessary vcug .
's study on 88 children with febrile uti revealed a significant difference between two groups with and without vur in terms of fever38.5 , pyuria25/high power field , and crp23.5 mg / l .
however , logistic regression analyses showed that only fever38.5 was an appropriate predictor of the presence of vur .
moreover , the above researchers revealed that crp50 mg / dl was a suitable predictor for the presence of high - grade vur .
performed a study on 140 children less than 5 years old with their first febrile uti and assessed variables including age , sex , and family history of uti , crp , and renal ultrasound .
their clinical approach yielded a sensitivity of 100% and specificity of 17% for predicting all vur grades and a sensitivity of 100% and specificity of 38% for predicting vur gradeiii . a similar study conducted by leroy et al .   on 149 children aged 1 month to 4 years with their first febrile uti
the results of the present study were somewhat similar to those of the studies by soylu et al .   and oostenbrink et al . .
although the quantitative crp level , rbc count in urine , results of renal ultrasound , and dmsa renal scan showed a significant difference between the groups with and without vur in the present study , the multivariate logistic regression analysis revealed a significant positive correlation between fever>38.2 and renal dmsa scan and vur . also , although there was a significant difference between the low - grade vur and high - grade vur groups regarding the neutrophil count , esr , leukocyturia , positive urinary nitrite , and ultrasound results , the multivariate logistic regression showed a significant positive correlation of high - grade vur with esr , positive urinary nitrite test , hyaline cast , and renal ultrasound . in a study by tseng et al
on 142 children less than 2 years old with their first febrile uti , the authors reported that the sensitivity , specificity , positive predictive value , and negative predictive value of dmsa renal scan in predicting vur were 88% , 37% , 36% , and 88% , respectively .
the above authors concluded that children with a normal dmsa renal scan rarely had vur and never had high - grade vur . a study conducted by camacho et al .   on 152 children with their first febrile uti showed that vur was more frequent in children with an abnormal dmsa renal scan than in children with a normal dmsa renal scan ( 48% vs. 12% ) .
the above researchers concluded that the risk of renal damage was very low in children with their first febrile uti and a normal dmsa renal scan .
another study pointed out the predictive value of dmsa renal scan and renal ultrasound in the diagnosis of high - grade vur .
that study reported the detection rate of ultrasound for low- and high - grade vur to be 86% and 41.7% , respectively , and that of the dmsa renal scan for low- and high - grade vur to be 88.4% and 37.5% , respectively . on the contrary , sorkhi et al .  
reported that the dmsa renal scan alone or along with renal ultrasound could not predict vur .
therefore , they argued that vcug must be done to diagnose vur . in the present study ,
the highest lrp was respectively related to the dmsa renal scan , renal ultrasound , crp20 mg / dl , and fever higher than 38.2. the dmsa scan had high sensitivity and specificity for the diagnosis of vur . in this respect ,
, it can be concluded that in the case of a normal dmsa scan , the risk of vur is very low , and performing vcug is unnecessary . although some studies mentioned procalcitonin as a predictor of vur , the relevant test is more costly than other routine tests , such as crp and esr , and is not available everywhere .
we hope that the results of the present study will help to avoid unnecessary vcug in children affected by their first febrile uti .
given that the present study was conducted in one educational hospital , further multicenter studies are recommended .
this study revealed that the best predictive markers for the presence of vur in children with their first febrile uti are the fever>38.2 and dmsa renal scan .
esr , positive urinary nitrite test , hyaline cast , and renal ultrasound are best predictive markers for the presence of high - grade vur .
 purposethis study was conducted to determine the predictive value of clinical , laboratory , and imaging variables for the diagnosis of vesicoureteral reflux in children with their first febrile urinary tract infection.materials and methodsone hundred fifty - three children with their first febrile urinary tract infection were divided into two groups according to the results of voiding cystourethrography : 60 children with vesicoureteral reflux and 93 children without . the sensitivity , specificity , positive and negative predictive value , likelihood ratio ( positive and negative ) , and accuracy of the clinical , laboratory , and imaging variables for the diagnosis of vesicoureteral reflux were determined.resultsof the 153 children with febrile urinary tract infection , 60 patients ( 39.2% ) had vesicoureteral reflux . there were significant differences between the two groups regarding fever>38 , suprapubic pain , c - reactive protein quantitative level , number of red blood cells in the urine , and results of renal ultrasound and dimercaptosuccinic acid renal scanning ( p<0.05 ) . 
 there were significant positive correlations between fever>38.2 and dimercaptosuccinic acid renal scanning and vesicoureteral reflux . 
 also , there were significant positive correlations between the erythrocyte sedimentation rate , positive urinary nitrite test , hyaline cast , and renal ultrasound and high - grade vesicoureteral reflux.conclusionsthis study revealed fever>38.2 and dimercaptosuccinic acid renal scanning as the best predictive markers for vesicoureteral reflux in children with their first febrile urinary tract infection . 
 in addition , erythrocyte sedimentation rate , positive urinary nitrite test , hyaline cast , and renal ultrasound are the best predictive markers for high - grade vesicoureteral reflux . 