title: Intrarenal reflux in primary vesicoureteral reflux.
abstract: OBJECTIVE
  To elucidate the significance of intrarenal reflux.
  
  
  METHODS
  We retrospectively analyzed 276 patients (age <5 years) with grade III to V vesicoureteral reflux. They were divided into two groups: 55 patients with intrarenal reflux and 221 patients without intrarenal reflux (control group). All patients received low-dose antibiotic prophylaxis.
  
  
  RESULTS
  The most common initial presentation in both groups was febrile urinary tract infection. On dimercaptosuccinic acid scan, the rate of decreased differential renal function (<40%) was significantly higher in the intrarenal reflux group than in the control group (51% vs 33%, P < 0.05). Breakthrough urinary tract infections were observed in 26 patients (47%) in the intrarenal reflux group and 61 patients (28%) in the control group (P < 0.01). There was no statistically significant difference regarding spontaneous resolution of reflux, which occurred in nine patients (16%) in the intrarenal reflux group and 32 patients (14%) in the control group. Surgical treatment was selected more often in the intrarenal reflux group (P < 0.05) because of the high incidence of breakthrough urinary tract infection.
  
  
  CONCLUSIONS
  The rate of spontaneous resolution of high-grade vesicoureteral reflux is similar between patients with and without intrarenal reflux. However, those with intrarenal reflux present are more likely to present a decreased differential renal function and breakthrough urinary tract infections. Consequently, surgical treatment is considered more frequently in cases with intrarenal reflux. Although high-grade vesicoureteral reflux with intrarenal reflux can be treated conservatively, physicians should take into account the higher risk of breakthrough urinary tract infections.
authors.affiliation: Department of Urology, Aichi Children's Health and Medical Center, Obu, Aichi, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Fukui
authors.forename: Masato
authors.initials: M
authors.lastname: Watanabe
authors.forename: Kaoru
authors.initials: K
authors.lastname: Yoshino
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007564:Japan / Q000453:epidemiology; D007668:Kidney / Q000473:pathology*; D008297:Male; D012189:Retrospective Studies; D014552:Urinary Tract Infections / Q000209:etiology*; D014718:Vesico-Ureteral Reflux / Q000150:complications* / Q000453:epidemiology / Q000473:pathology