title: Interobserver variation in the sonographic estimation of renal volume in children.
abstract: OBJECTIVE
  To quantify the interobserver variability in the sonographic estimation of renal volume in children.
  
  
  METHODS
  Three observer pairs measured the lengths and diameters of 176 kidneys in 90 children. Renal volumes were estimated from the formula for a prolate ellipsoid. The mean and standard deviation of the absolute and percentage differences between observers were calculated. The 95 % limits of agreement for each pair of observers were derived. Log-transformed data were used to derive overall limits of agreement.
  
  
  RESULTS
  Absolute interobserver variation increased with renal volume. Percentage variation was independent of renal size. There is a 95 % probability that a measurement of renal volume by one observer will be between 0.69 and 1.44 times a measurement made by a different observer.
  
  
  CONCLUSIONS
  The interobserver variation in the sonographic estimation of renal volume represents approximately 2-3 years' normal growth in children aged over 2 years.
authors.affiliation: Department of Radiology, British Columbia's Children's Hospital, 4480 Oak Street, Vancouver BC V6H 3V4, Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: Sargent
authors.forename: G
authors.initials: G
authors.lastname: Long
authors.forename: M
authors.initials: M
authors.lastname: Karmali
authors.forename: S M
authors.initials: SM
authors.lastname: Cheng
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007668:Kidney / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D008297:Male; D015588:Observer Variation; D011446:Prospective Studies; D014463:Ultrasonography