title: Determining the incidence of horseshoe kidney from radiographic data at a single institution.
abstract: OBJECTIVE
  An estimated 150,000 children are born with birth defects each year. One of the most frequent genitourinary abnormalities is horseshoe kidney (HSK). The incidence of HSK in the population is estimated to be 1/400 to 1,600 births based on autopsy data from the 1940s and 1950s. We prospectively evaluated the incidence of HSK based on radiographic studies to determine the contemporary incidence of HSK.
  
  
  METHODS
  In a 6-month period patients undergoing abdominal computerized tomography, renal ultrasonography and excretory urography were screened for HSK. After identification medical charts were reviewed for demographics, history, study indication and findings. A literature review of 12 studies of 825 patients with HSK was compared with the current series with regard to common associated findings.
  
  
  RESULTS
  From 15,320 radiographs 23 patients were identified with HSK for an overall incidence of 1/666. Computerized tomography, excretory urography and ultrasound identified 16, 5 and 2 patients, respectively, while 16 were male, 7 were female, 20 were adults and 3 were children. The most common concomitant urological disorder was nephrolithiasis in 9 patients (39%), prompting operative intervention in 4. The radiographic incidence of HSK closely matched data from autopsy series and yet it differed from that in current radiographic series using ultrasound in the perinatal period.
  
  
  CONCLUSIONS
  Our radiographic evaluation of the HSK incidence closely matches past autopsy series. This finding suggests that the incidence of HSK remains stable despite an increasing number of birth defects. Moreover, it appears that radiographic studies can accurately estimate the incidence of congenital anatomical disorders. Our data suggest that HSK is a relatively benign condition with a low requirement for operative intervention in these incidentally identified patients.
authors.affiliation: Comprehensive Kidney Stone Center, Division of Urology, Department of Surgery, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Alon Z
authors.initials: AZ
authors.lastname: Weizer
authors.forename: Ari D
authors.initials: AD
authors.lastname: Silverstein
authors.forename: Brian K
authors.initials: BK
authors.lastname: Auge
authors.forename: Fernando C
authors.initials: FC
authors.lastname: Delvecchio
authors.forename: Ganesh
authors.initials: G
authors.lastname: Raj
authors.forename: David M
authors.initials: DM
authors.lastname: Albala
authors.forename: Richard
authors.initials: R
authors.lastname: Leder
authors.forename: Glenn M
authors.initials: GM
authors.lastname: Preminger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001344:Autopsy / Q000706:statistics & numerical data; D002140:California / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007668:Kidney / Q000002:abnormalities* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography; D014564:Urogenital Abnormalities / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology; D014567:Urography