title: Pediatric renal abscesses: A contemporary series.
abstract: BACKGROUND
  Pediatric renal abscesses are an uncommon diagnosis, with a paucity of data comparing treatment modalities. Patient presentation ranges from persistent dull flank/abdominal pain with or without fevers, to those who are overtly ill, presenting with hemodynamic instability and bacteremia. Management for pediatric renal abscesses is typically based on results extrapolated from small series in adult cohorts, with conservative measures recommended when the lesion is <3 cm.
  
  
  OBJECTIVE
  This study evaluated the presentation, management and outcomes of a contemporary cohort of pediatric patients with renal abscesses.
  
  
  METHODS
  A total of 16 consecutive pediatric patients with radiologically diagnosed intra-renal or peri-nephric abscesses from 1990 to 2012 were identified. Patients were identified by querying institutional records via ICD-9 and CPT codes referencing renal abscess. Charts were retrospectively reviewed to evaluate multiple clinical variables, including: presenting symptoms, size of abscess, management strategy and clinical outcomes. Clinical resolution was confirmed via repeat ultrasound or computed tomography.
  
  
  RESULTS
  The median age at presentation was 13 years (range 1 month-18 years) and 13/16 patients (81%) were female. Abscess formation was secondary to: urinary tract infection in 13 (81%); hematogenous seeding from a skin infection in one (6%); and an unknown etiology in two (12%) patients. The most common organism identified on urine culture was Escherichia coli (10, 77%). Hematogenous seeding was confirmed in only one case, with Staphylococcus aureus growing on culture from both a cutaneous lesion and percutaneous drainage of the renal lesion. Overall, abscesses were a median of 2.2 cm (IQR 2, 3.7), with 13 (81%) successfully managed with conservative therapy, including intravenous antibiotics, with resolution on repeat imaging at a median of 21 days (range 6-55). For patients presenting with abscesses ≤3 cm, conservative measures were employed in 10/11 cases, with 100% success rate. Three patients had larger abscesses (3.8, 4, and 10 cm), which resolved after treatment with percutaneous drainage. A voiding cystourethrogram was performed in 10 patients, with two (20%) detecting an abnormality (low-grade vesicoureteral reflux, which required no further intervention).
  
  
  CONCLUSIONS
  Pediatric renal abscesses were most commonly small and secondary to an E. coli UTI. Most small (≤3 cm) renal abscesses resolved with conservative management. Percutaneous drainage should be considered for lesions >3 cm and in patients who remain persistently febrile, despite culture-specific antibiotics, are immunocompromised or critically ill.
authors.affiliation: Department of Urology, Mayo Clinic, Rochester, MN 55905, USA. Electronic address: Linder.Brian@mayo.edu.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Linder
authors.affiliation: Department of Urology, Mayo Clinic, Rochester, MN 55905, USA. Electronic address: Granberg.Candace@mayo.edu.
authors.forename: Candace F
authors.initials: CF
authors.lastname: Granberg
mesh_terms: D000038:Abscess / Q000175:diagnosis* / Q000628:therapy; D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D004322:Drainage / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007674:Kidney Diseases / Q000175:diagnosis* / Q000628:therapy; D008297:Male; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D000900:Anti-Bacterial Agents
keywords: Management; Pediatric; Renal abscess