Don't stop performing voiding cystourethrography in young children after the initial febrile urinary tract infection—at least not yet
Article Outline
Lee M, Lin C, Huang F, Tsai T, Huang C, Tsai J. Screening young children with a first febrile urinary tract infection for high-grade vesicoureteral reflux with renal ultrasound scanning and technetium-99m-labeled dimercaptosuccinic acid scanning. J Pediatr 2009;154:797-802.
Question
Among young children with a first urinary tract infection (UTI), how accurate are renal ultrasound scanning and 99m-technetium–dimercaptosuccinic acid (DMSA) scintigraphy in diagnosing high-grade vesicoureteral reflux (VUR)?
Design
Retrospective case series.
Setting
Single medical center in Taipei, Taiwan.
Participants
699 children (aged 2 months to 2 years) who were diagnosed with a first febrile UTI and underwent renal ultrasound scanning, DMSA scanning, and voiding cystourethrography (VCUG).
Outcomes
Sensitivity and specificity of renal ultrasound scanning, DMSA scanning, and a both-test strategy.
Main Results
High-grade VUR (grades III-V) was diagnosed in 119 (17.0%) of the children. Signs of renal hypodysplasia (OR, 16.2; positive likelihood ratio [LR+], 14.6), cyclic dilation of pelvicaliceal system (OR, 11.7; LR+, 10.6), hydroureter (OR, 4.0; LR+, 3.7) with renal ultrasound scanning, and renal hypodysplasia (OR, 8.8; LR+, 8.1), acute pyelonephritis (OR, 2.76; LR+, 1.7) with DMSA scanning were associated with high-grade VUR. The sensitivities for high-grade VUR of ultrasound scanning alone (67.2%) or DMSA scanning alone (65.5%) were not as good as that of a both-test strategy, which had a sensitivity of 83.2%. The likelihood ratios for the both-test strategy were 1.3 for a positive result and 0.45 for a negative result.
Conclusions
Renal ultrasonography and DMSA scanning should both be routinely performed in children with a first febrile UTI. VCUG is only indicated when abnormalities are apparent on either ultrasound scanning, DMSA scanning, or both.
Commentary
The necessity of performing a VCUG after the initial febrile UTI has been a topic of debate for years. Currently, most authorities still recommend performance of a VCUG, primarily because of the high prevalence of vesicoureteral reflux in infants with febrile UTI and because of the presumed risk of reflux nephropathy and associated complications such as hypertension and even end-stage renal disease. However, there are data that suggest that some of the renal damage attributed to VUR may actually be congenital rather than acquired as a result of reflux and that the incidence of VUR-associated complications is much lower than previously believed.1 Add to that the admitted unpleasantness of the VCUG procedure, and the question naturally follows: what is the actual benefit of performing this test? Lee et al answer this question by saying that VCUGs should only be performed in those children with abnormalities on a renal ultrasound or DMSA scan, both performed within the first few days after the diagnosis of febrile UTI. An important limitation of this study, not addressed in the article, is its retrospective design. The lack of a clearly defined protocol followed prospectively in all eligible patients introduces the possibility of selection bias, which hampers one's ability to draw clear conclusions from the data. Although it might be argued that the relatively large numbers of patients studied is sufficient to overcome the effects of selection bias, this cannot be guaranteed. Additionally, all patients in this study were hospitalized patients, in whom it is relatively easy to obtain multiple imaging studies. In North America, the prevailing trend is for outpatient management of young children with febrile UTIs.2 From a practical perspective, it would be extremely difficult to schedule every young child with a febrile UTI for both a renal ultrasound scan and DMSA scan on an outpatient basis during their acute infection. Although this study certainly raises intriguing questions deserving of further prospective study, for now I would urge caution before we stop sending patients to the Radiology Department for VCUGs.
References
PII: S0022-3476(09)00861-0
doi:10.1016/j.jpeds.2009.08.029
© 2009 Mosby, Inc. All rights reserved.
