1. Description of intervention/study
PREDICTIVE VALUE OF RENAL ULTRASOUND IN DIAGNOSING VESICOURETERAL REFLUX
IN CHILDREN WITH URINARY TRACT INFECTIONS
Avanikkha Elayappen MD1, Ketan N. Patel MD2, Shivaiah Balachandra MD3
1- PGY II Pediatric Resident, UTMB , Galveston, Texas
2-Assistant Professor, Department of Pediatric Nephrology, UTMB
3-Associate Professor, Department of Pediatric Nephrology, UTMB
Introduction
Results
Urinary tract infection (UTI) is one of the most common bacterial infections with a prevalence of 5% in children below two years and 7.8% in older children up to 18 years of age. It affects 3.5% of children in the United States annually[1]. Two thirds of febrile UTI’s in children are acute pyelonephritis(PN) [2]. VUR (Vesicoureteral Reflux) is a common urinary tract abnormality observed in children with PN. Approximately eight to thirty percent children experience symptomatic/asymptomatic recurrent UTI[3]. Reflux nephropathy was the cause of chronic kidney disease (CKD) in 8.4% of children in the North American Pediatric Renal Trials and Collaborative Studies database [NAPRTCS]. Early detection of VUR is important because of the associated risk of reflux nephropathy, renal parenchymal scarring that can lead to hypertension, CKD and end stage renal disease [ESRD]. High-grade reflux is four to six times more likely to cause renal scarring than low-grade reflux and eight to ten times more than those without reflux. The purpose of this study was to evaluate the predictive value of RUS in detecting VUR in children with UTI.
Of the 793 renal units, 132 units (16.6%) showed reflux on VCUG and the remaining 661 units did not reveal any reflux on VCUG .
Among the 132 renal units with positive findings on VCUG, only 46 (34.8%) were abnormal on RUS.
104 renal units had low grade reflux (grade 1,2,3) on VCUG, of which only 27 were abnormal on RUS (26% sensitivity).
28 renal units had high grade reflux (grade 4,5) on VCUG, of which 19 were abnormal on RUS (68% sensitivity).
TOTAL
N=793
+VCUG
N=132
+1,+2,+3
VCUG
N=104
+4, +5
N=28
+USG
N=171
-USG
N=490
N=27
N=19
N=77
N=9
-VCUG
N=661
Abstract
Guidelines recommend obtaining a renal ultrasonography (RUS) for children after a first UTI/PN to diagnose anatomic abnormalities [4,5].There is still controversy over the value of RUS in identifying reflux nephropathy in children with acute PN with or without VUR.[6,7,8]. The studies performed so far have looked for a correlation between renal ultrasonography and voiding cystograms and have not been able to predict reflux based on renal ultrasonography findings. Our study looked for abnormal ultrasonographic findings including discrepancy in renal size, increased or decreased renal parenchymal echogenicity, renal pelviectasis, hydronephrosis, solitary kidney, pelvic kidney, other renal anomalies and correlated with various grades of reflux. Analysis of the renal units revealed that most of the low grade refluxes were not detected in ultrasound. About one third of high grade reflux which causes upper urinary tract changes were likely to be missed in ultrasound.
Conclusions
High grade reflux is more commonly associated with RUS findings with a sensitivity of only 68%. Low grade reflux is associated with a sensitivity of only 26%. Our study implicates that even a well performed RUS may not detect 32% of high grade reflux and will almost always not detect low grade reflux. We recommend VCUG for all patients with suspected VUR rather than renal ultrasound.
References
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Hoberman A, Wald ER, et al. Urinary tract infection in young febrile children. Pediatr Infect Dis J Jan;16(1):11-7.
Conway PH, Cnaan A, Zaoutis T, Henry BV, Grundmeier RW, Keren R. Recurrent urinary tract infections in children: risk factors and association with prophylactic antimicrobials.JAMA. 2007;298
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Hoberman A, Charron M, Hickey RW, Baskin M, Kearney DH, Wald ER. Imaging studies after a first febrile UTI in young children. New Engl J Med Jan 16;348(3):
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Evans MD, Meyer JS, Harty MP. Assessment of increase in renal pelvic size on post-void sonography as a predictor of vesicoureteral reflux. Pediatr Radiol Apr;29(4):291-4.
DiPietro MA, Blane CE, Zerin JM. Vesicoureteral reflux in older ichildren: concordance of US and voiding cystourethrographic findings. Radiology: Dec; 205(3):821-2.
Description of intervention/study
We conducted a retrospective analysis of renal ultrasonography and VCUG studies performed in children between the age group 0-18 years diagnosed with UTI at our hospital from January 2005 to April 2008.
For analytical purposes each kidney was considered as a separate unit and a total of 793 units were analyzed for the study.
All data were analyzed with Statistical Package for the Social Sciences (SPSS).
Renal ultrasonography with pelvic dilatation above 7mm, discrepancy in renal size more than 1.5 cm or evidence of cortical thinning were considered abnormal.
VUR was graded based on the International Reflux Grading system.
2013 Texas Pediatric Society Electronic Poster Contest