title: The presence of horseshoe kidney does not affect the outcome of percutaneous nephrolithotomy.
abstract: OBJECTIVE
  Large or complex calculi within a horseshoe kidney can present a challenge because many cases are associated with other aberrant anatomy. We performed a study to define the outcome of patients with a horseshoe kidney who were treated with percutaneous nephrolithotomy (PNL).
  
  
  METHODS
  From August 1999 to February 2007, 44 PNLs were performed in 35 patients for calculi within a horseshoe kidney. Mean age was 55.4 years. Parameters evaluated to assess the outcomes of PNL included presenting symptoms, stone burden, location of access, stone-free rate, need for secondary intervention, length of stay (LOS), complication rate, stone analysis, and metabolic data.
  
  
  RESULTS
  The average stone burden per kidney was 2.59 cm (range 1-6.2 cm). Single percutaneous access was used in 97.7%. Location of the access tract was upper pole (82.2%), interpolar (13.4%), and lower pole (4.4 %). Flexible nephroscopy was performed in all patients. The stone-free rate after primary PNL was 84.1%. Second-look nephroscopy was performed in five kidneys. Overall stone-free rate was 93.2%. Average LOS was 1.92 days (range 1-4 d). Overall complication rate was 14.3%. Stone analysis revealed predominantly calcium stones, and metabolic abnormalities were demonstrated in all patients with 24-hour urine studies.
  
  
  CONCLUSIONS
  PNL is the treatment of choice for large and/or complex stones. The presence of a horseshoe kidney does not affect the outcome of PNL. Upper pole access is usually preferred, and flexible nephroscopy is essential to maximize stone-free rates. SA and metabolic data support the premise that calculus formation is a metabolic event.
authors.affiliation: Department of Urologic Surgery, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA. nicole.miller@vanderbilt.edu
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Miller
authors.forename: Brian R
authors.initials: BR
authors.lastname: Matlaga
authors.forename: Shelly E
authors.initials: SE
authors.lastname: Handa
authors.forename: Larry C
authors.initials: LC
authors.lastname: Munch
authors.forename: James E
authors.initials: JE
authors.lastname: Lingeman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003710:Demography; D005260:Female; D006801:Humans; D053565:Hypercalciuria / Q000150:complications; D007430:Intraoperative Care; D007669:Kidney Calculi / Q000150:complications* / Q000628:therapy*; D007674:Kidney Diseases / Q000150:complications* / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous; D011182:Postoperative Care; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome