Journal review Renal damage detected by DMSA, despite normal renal ultrasound, in children with febrile UTIPublished in Journal of Pediatric Urology (2015) 11, 126.e1e126.e7By N.C. Bush, M. Keays, C. Adams, K. Mizener, K. Pritzker c, W. Smith, J. Traylor, C. Villanueva, W.T. Snodgrass

1999 American Academy of Pediatrics guidelinesrenal-bladder ultrasound (RBUS) and VCUG after the first FUTI in children younger than 2 years of age

2011 American Academy of Pediatrics guidelinesdo not support the use of antimicrobial prophylaxis to prevent febrile recurrent UTI in infants without vesicoureteral reflux (VUR) or with grade I to IV VUR. Therefore, a voiding cystourethrography (VCUG) is not recommended routinely after the first UTIVCUG is indicated if renal and bladder ultrasonography reveals hydronephrosis, scarring, or other findings that would suggest either highgrade VUR or obstructive uropathy and in other atypical or complex clinical circumstances. VCUG should also be performed if there is a recurrence of a febrile UTI

Questionprevious reports have demonstrated poor correlation between RBUS and renal scarring, compared to the gold standard DMSA scintigraphy, with sensitivity ranging from 5 to 47%

Accordingly, RBUS alone may fail to identify patients with underlying renal damage who may benefit from cystography to identify VUR.

purpose of the study was to determine how well RBUS performed in detecting renal damage that was identified by DMSA performed 3 months after FUTI.

MethodsCross-sectional studymulti-provider pediatric urology group evaluated the children for UTI and/or VUR between October 2008 and December 2012 using a standardized protocolAll children aged 018 years, with at least one FUTI, who underwent RBUS and DMSA were evaluated. Those with a solitary kidney, ectopic ureter, ureterocele, PUV, prune belly syndrome, and/or neurogenic bladder were excluded.

DefinitionsRenal-bladder ultrasound was defined as abnormal, with the presence of any of the following: hydronephrosis grades IIV by Society of Fetal Urology criteria (including pelviectasis without caliectasis); hydroureter 7 mm in transverse diameter; renal scar defined by abnormal focal renal contour with parenchymal thinning; and/or size discrepancy 1 cm between kidneys. Children with suspected renal duplication anomalies were classified as normal, unless the renal size discrepancy was 1 cm between the kidneys and/or hydro(uretero)nephrosis was present.

DefinitionsDMSA scans were independently reviewed by two pediatric radiologistsResults were graded using the grading scale adapted from the Randomized Intervention for Children with Vesicoureteral Reflux (RIVUR) trial

DefinitionsBecause this protocol began before the 2011 AAP guidelines on UTI, the definition of UTI was according to prior guidelinesa symptomatic child with >50,000 colony-forming units (CFU)/ml on catheterized specimens or >100,000 CFU/ml in bag or voided specimens.

Data analysisThe primary outcome was abnormal DMSA. Sensitivity, specificity, positive predictive value, negative predictive value, and false negative rates were calculated for normal and abnormal RBUSMultiple logistic regression was used to estimate the odds of abnormal DMSA with pre-determined risk factorsRBUS (normal/abnormal), number of FUTI (1, 2, 3), age (months)GenderGrade of VUR

On average, DMSA was performed 3.5m after baseline RBUS.

In view of RBUS in identifying children with renal damage on DMSA:Sensitivity 34% (95% CI 2642%),specificity 88% (95% CI 8591%)positive predictive value (true positive) of 47% (95% CI 3757%)negative predictive value (true negative) of 81% (95% CI 7784%) (Table 3). false negative rate of 19% (95% CI 1623%), with nearly one in every five children demonstrating focal cortical defects and/or diminished renal function on DMSA despite a normal RBUS after FUTI

Among the 149 children with abnormal DMSA, 47 (32%) had diminished ipsilateral renal function of less than 44% Out of those 47 children, 35(35/99 35%) of those with normal RBUS and 12(12/50 24%) of those with abnormal RBUS (P = 0.22)

VUR was similarly present in children with normal RBUS/abnormal DMSA, compared to those with abnormal RBUS/abnormal DMSA (76% vs 74%, P = 0.90)VCUG was performed on abnormal DMSA, VUR was identified in 76%, including grades IV in 5 (4%), 26 (18%), 35 (24%), 26 (18%), and 16 (11%), respectively, and no VUR identified in 35 (24%).

Among the 149 children with abnormal DMSA, 47 (32%) had diminished ipsilateral renal function of less than 44% Out of those 47 children, 35(35/99 35%) of those with normal RBUS and 12(12/50 24%) of those with abnormal RBUS (P = 0.22)

VUR was similarly present in children with normal RBUS/abnormal DMSA, compared to those with abnormal RBUS/abnormal DMSA (76% vs 74%, P = 0.90)VCUG was performed on abnormal DMSA, VUR was identified in 76%, including grades IV in 5 (4%), 26 (18%), 35 (24%), 26 (18%), and 16 (11%), respectively, and no VUR identified in 35 (24%).

Odds of risk factor for abnormal DMSA

DiscussionOn detecting renal damage, ie abnormal DMSA, RBUS had poor sensitivity (34%) and a low positive predictive value (47%) Also, it had a false negative rate ranging from 14% in children aged 24 months to 23% in children aged 2 years and olderThus, a substantial portion of children had abnormal DMSA, despite normal RBUS, which suggests that renal damage will not be detected if only RBUS is performed.

Of the children younger than 2 years of age and who were referred after one FUTI with a normal RBUS, 10% had an abnormal DMSA , all were additionally found to have VUR ranging from grades IVOf all age with one FUTI with a normal RBUS, 19% had an abnormal DMSA, 80% had VUR grade I-V.VCUG was performed on abnormal DMSA, VUR was identified in 76%, including grades IV in 5 (4%), 26 (18%), 35 (24%), 26 (18%), and 16 (11%)Close correlation between abnormal DMSA and VUR, thus RBUS alone failed to detect substantial portion of high grade VUR

DiscussionBoth reimplantation of ureter and prophylactic antibiotic was shown to reduce recurrent FUTIOther study demonstrate that each FUTI increases the likelihood for renal damage on DMSA (2 FUTIs: OR 1.9, 95% CI 1.083.42; and 3 FUTIs: OR 2.4, 95% CI 1.401.21)

ConclusionNormal RBUS failed to detect any renal function loss and/or cortical renal defects found on DMSA that were obtained 3 months after initial FUTI in 10% of children 2 years old, and in 25% of children of all ages with two or more FUTI. Of these children, 76% were found to have VUR and were therefore considered to have continued risk for recurrent FUTI and additional renal damage. Imaging after initial FUTI should include acute RBUS and delayed DMSA, reserving cystography for those with abnormal DMSA and/or recurrent FUTI.

Commentary to the articleApproximately 3% of girls and 1% of boys develop a symptomatic UTI in childhood, yet 85% of children with a first symptomatic or febrile UTI do not develop a recurrent UTI. Thus, large number of children who would be exposed to radiation during a costly and lengthy test, but would never develop a recurrent UTI. Consider prevalence of renal abnormality on DMSA scan, and if VCUG was done if DMSA abnormal, risk reduction of recurrent UTI in giving antibiotic prophylaxis number need to treat is 275While if VCUG was done in RECURRENT UTI, and give antibiotic prophylaxis accordingly, number need to treat is 20