title: Evaluation of sonographic renal parenchymal area in the management of hydronephrosis.
abstract: OBJECTIVE
  We used quantitative parameters of renal sonography to differentiate children with significant obstruction requiring surgical intervention from those without significant obstruction who were followed conservatively.
  
  
  METHODS
  We retrospectively reviewed the records of children who underwent evaluation for hydronephrosis. Those with a history of vesicoureteral reflux, anatomical abnormalities or neurogenic bladder were excluded from study. Patients were divided according to hydronephrosis grade into groups 1-grades III and IV followed conservatively, 2-grades III and IV requiring surgical intervention, 3-unilateral grade II and 4-bilateral. All images were scanned into a computer. Renal parenchymal and pelvic area was determined using National Institutes of Health image software. Parenchymal-to-pelvic area ratios were calculated from all images. We evaluated the ability of these measurements to determine the likelihood of surgical intervention.
  
  
  RESULTS
  The records of 81 children were available for analysis. Deterioration in parenchymal area growth was a predictor of surgical intervention. Such patients had catch-up growth of the affected kidney after pyeloplasty. A parenchymal-to-pelvic area ratio of greater than 1.6 on the initial ultrasound study after birth predicted cases that would need pyeloplasty in the future (p <0.05). No patient with grade II hydronephrosis required surgical intervention.
  
  
  CONCLUSIONS
  Following serial parenchymal area on serial ultrasound is useful for evaluating children with hydronephrosis. Those with a parenchymal area below the nomogram for growth usually require pyeloplasty. A parenchymal-to-pelvic area ratio of less than 1.6 on the initial ultrasound study after birth in patients with prenatally diagnosed ureteropelvic junction obstruction or on initial ultrasound in those diagnosed postnatally indicated the need for surgical intervention in this limited series.
authors.affiliation: Department of Urology, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: L V
authors.initials: LV
authors.lastname: Rodríguez
authors.forename: J
authors.initials: J
authors.lastname: Lock
authors.forename: W A
authors.initials: WA
authors.lastname: Kennedy
authors.forename: L M
authors.initials: LM
authors.lastname: Shortliffe
mesh_terms: D002675:Child, Preschool; D006801:Humans; D006869:Hydronephrosis / Q000000981:diagnostic imaging*; D007223:Infant; D007231:Infant, Newborn; D007668:Kidney / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D014463:Ultrasonography