title: Isolated low initial differential renal function in patients with primary non-refluxing megaureter should not be considered an indication for early surgery: A multicentric study.
abstract: BACKGROUND
  Low initial differential renal function (DRF) in patients with primary non-refluxing megaureter (PNRM) is considered an indication for surgery as are an increase of dilatation and symptoms.
  
  
  OBJECTIVE
  We hypothesized that low DRF is not necessarily a result of obstruction, but may be due to impaired development of the upper urinary tract. Thus, in the absence of symptoms, there is a low risk for further loss of renal function. This study aimed to assess whether initially low DRF is a reliable indicator of obstruction.
  
  
  METHODS
  We reviewed data from four university centers between 1995 and 2010. Patients under 12 months of age with unilateral primary non-refluxing megaureter (PNMR) and a DRF between 10% and 40%, and followed minimally 24 months, were included. Patients were placed in two groups based on management: group A, surgical; group B, conservative. The dynamics of DRF in relation to age and type of treatment was studied. In each patient we recorded the earliest (initial) DRF, the last known (final) DRF, the age when MAG-3 scans were performed and the type of treatment.
  
  
  RESULTS
  From 25 patients, 16 were treated surgically (group A) and 9 followed conservatively (group B). The initial mean DRF in group A was 33.1% and in group B 34.5%, at a mean age 3.0 and 3.6 months, respectively. The final mean DRF in group A was 40.1% and in group B 43%, at a mean age 59.9 and 46.3 months, respectively. Using two-way repeated ANOVA (age [initial DRF, final DRF] vs. group [group A, group B]), we found non-significant difference between the groups in the DRF, F (1, 21) = 0.96, p = 0.338, while we observed statistically significant and similar increase from the initial to final DRF in both groups, F (1, 21) = 16.66, p = 0.001 (Figure).
  
  
  CONCLUSIONS
  This is the first study focusing on the evolution of renal function in patients with PNRM and low initial DRF. Results suggest that the diagnosis of obstruction is inaccurate in most infants with unilateral PNRM if it is based on low initial DRF only. Renal deterioration rarely occurs in asymptomatic patients, and even profoundly impaired kidneys have potential for improvement. Limitations of our study include retrospective design and lack of standardization of treatment among the four centers.
  
  
  CONCLUSIONS
  Low DRF in asymptomatic and anatomically stable patients with PNMR should not be considered an indication for early surgery. These findings challenge current practice and should be confirmed by a prospective study.
authors.affiliation: Department of Urology, General Teaching Hospital and Charles University 1-st Faculty of Medicine, Prague, Czech Republic. Electronic address: marcel.drlik@seznam.cz.
authors.forename: Marcel
authors.initials: M
authors.lastname: Drlík
authors.affiliation: Department of Pediatrics, Olomouc University Hospital, Olomouc, Czech Republic.
authors.forename: Hana
authors.initials: H
authors.lastname: Flogelová
authors.affiliation: Department of Pediatric Surgery, University Hospital Brno, Brno, Czech Republic.
authors.forename: Kubát
authors.initials: K
authors.lastname: Martin
authors.affiliation: Department of Urology, Hradec Králové University Hospital, Hradec Králové, Czech Republic.
authors.forename: Tomášek
authors.initials: T
authors.lastname: Jan
authors.affiliation: Department of Pediatric Surgery, University Hospital Brno, Brno, Czech Republic.
authors.forename: Zerhau
authors.initials: Z
authors.lastname: Pavel
authors.affiliation: Department of Urology, Olomouc University Hospital, Olomouc, Czech Republic.
authors.forename: Šmakal
authors.initials: Š
authors.lastname: Oldřich
authors.affiliation: Department of Urology, Hradec Králové University Hospital, Hradec Králové, Czech Republic.
authors.forename: Novák
authors.initials: N
authors.lastname: Ivo
authors.affiliation: Department of Methodology, Faculty of Physical Education and Sport, Charles University, Prague, Czech Republic.
authors.forename: Komarc
authors.initials: K
authors.lastname: Martin
authors.affiliation: Department of Urology, General Teaching Hospital and Charles University 1-st Faculty of Medicine, Prague, Czech Republic.
authors.forename: Kočvara
authors.initials: K
authors.lastname: Radim
mesh_terms: D004108:Dilatation, Pathologic; D006801:Humans; D007223:Infant; D007668:Kidney / Q000503:physiopathology*; D007677:Kidney Function Tests; D012189:Retrospective Studies; D013997:Time Factors; D014515:Ureteral Diseases / Q000503:physiopathology* / Q000601:surgery; D013520:Urologic Surgical Procedures
keywords: Conservative treatment; Low differential renal function; Primary non-refluxing megaureter