This study has considered the clinical utility of VCUG in cases where otherwise healthy children have presented with a kidney abscess. We examined whether kidney abscesses should indicate VCUG and whether this would influence management and outcomes for children when VUR is found, particularly considering the present indications for VCUG relating to recurrent febrile UTI [4].
Our study indicates that children without any underlying health conditions who present with a kidney abscess are likely to have VUR on VCUG at a similar rate as those with a first febrile uncomplicated upper UTI [8]. In our study, 29% of children had VUR VCUG following a first presentation with kidney abscess, compared to 25–40% following a first pyelonephritis.[8] This finding aligns with reports from other published series [2]. Additionally, we observed an equal proportion of kidney abscesses in male and female children. Regarding secondary outcomes related to kidney abscess, our results suggest no statistically significant change in the proportion of kidney scarring in those with high-grade VUR.
Regarding the surgical management of children with VUR identified following VCUG for a kidney abscess, high-grade VUR, as demonstrated in the Mayo Clinic case series published in 2016 by Linder and Granberg, did not indicate surgery [2]. In this cohort, three out of the four procedures performed were prompted by the recurrence of pyelonephritis, while the remaining case of high-grade VUR was managed conservatively. The recurrence of pyelonephritis indicated the need for three of the four procedures undertaken, with the other case of high-grade VUR being managed conservatively. This indicates that although the rate of VUR identified in this population is similar to that of first febrile UTI cases, the decision for surgery is made on an individualized basis and it is primarily recommended in cases of recurrent febrile UTI with kidney scarring, aligning with European guidelines.[4] Therefore, VCUG for children with kidney abscesses did not directly impact the management or outcomes for these patients.
Conversely, the VCUG results played an important role in tailoring antibiotic prophylaxis in accordance with current practices [4]. Specifically, children without VUR or those who were already potty-trained with low-grade reflux did not receive treatment. On the other hand, infants with low-grade VUR or children with high-grade VUR, irrespective of age, received treatment until achieving toilet training or surgery.
In our study, the most common organism identified was E. coli, which is in keeping with the literature [2, 19, 20]. All initial abscesses in the present series were treated conservatively, with none requiring percutaneous drainage. This is consistent with the literature that suggests conservative management with broad-spectrum intravenous antibiotics is a suitable first-line option [2, 19, 21, 22]. In contrast to the literature, which suggests abscesses over 30 mm should be considered for percutaneous drainage, the abscesses in our cohort larger than this were all treated successfully [20, 21].
This study’s limitations include its retrospective single-centre design and relatively small sample size. Two children in the study were also not initially reviewed at our centre, meaning there are some limitations to the data available for these children. The indications for DMSA were left to the consideration of the physicians. However, contrary to other studies, we excluded children with known urological or other comorbidities. This means our findings are limited to a cohort of children without any background medical history [23].
Due to our small sample size and the inability to accurately rule out an association between VCUG-identified VUR and a first kidney abscess in a paediatric patient, larger multicentre studies are needed to validate these findings. Further studies on paediatric kidney abscesses would also contribute to establishing stronger evidence for future VCUG guidelines, as international guidelines currently lack a substantial evidence base [4]. Identifying how high-grade VUR may impact subsequent management in a larger cohort is still warranted.
Overall, the data gathered herein suggest that the prevalence of VUR mirrors that found in studies utilizing VCUG following febrile UTI without kidney abscess. In this current series, surgical interventions were predominantly prompted by recurrent pyelonephritis accompanied by kidney scarring, irrespective of VCUG findings.
Conversely, VCUG results guided the prescription of antibioprophylaxis according to current practices. Our findings imply that the clinical utility of VCUG is similar in children, whether they present with an abscess or an uncomplicated pyelonephritis. Consequently, we propose uniform VCUG indications, regardless of abscess presence, with recurrent febrile UTI serving as the primary criterion for assessment, or when imaging suggests high-grade VUR or kidney scarring. Despite the absence of overt chronic kidney disease in this series over a 3-year follow-up period, implementing nephroprotection measures is recommended in the long term.