title: The impact of proximal stone burden on the management of encrusted and retained ureteral stents.
abstract: OBJECTIVE
  Managing the encrusted and retained ureteral stent is a potentially complex challenge. To improve surgical planning, we hypothesized that proximal stone burden is the most important factor associated with complicated removal, and that computerized tomography more accurately estimates stone burden than plain film x-ray of the kidneys, ureters and bladder.
  
  
  METHODS
  Records were reviewed of patients undergoing surgical removal of an encrusted and retained ureteral stent or nephrostomy at Ben Taub General Hospital from 2007 to 2009. Preoperative imaging consisted of a plain x-ray of the kidneys, ureters and bladder and/or computerized tomography of the abdomen/pelvis. Each encrusted tube was assessed using the FECal (forgotten, encrusted, calcified) grading system and associated stone burden was calculated. Univariate and multivariate analyses were performed to determine factors associated with the need for multiple surgeries.
  
  
  RESULTS
  A total of 55 encrusted and retained ureteral stents and 1 nephrostomy were removed from 52 patients. Mean tube duration was 24.9 months. Most tubes were removed endoscopically (94.2%). Of the patients 21.2% required multiple surgical procedures to remove each tube. Computerized tomography graded stone burden more accurately than plain x-ray of the kidneys, ureters and bladder (94.9% vs 64.4%, p = 0.01). Plain x-ray of the kidneys, ureters and bladder underestimated proximal stone burden in 44.4% of patients who underwent multiple surgeries. When dividing stone burden into 3 categories (0 to 100, 101 to 400 and greater than 401 mm(2)) only proximal stone burden correlated with multiple surgeries and surgical complications (p = 0.01 for both). On multivariate analysis only proximal stone burden was associated with multiple surgeries to remove each tube (OR 12.1, 95% CI 1.5-95.9, p = 0.02 for 101 to 400 mm(2) and OR 18.1, 95% CI 1.7-192.8, p = 0.02 for greater than 401 mm(2)).
  
  
  CONCLUSIONS
  In patients with encrusted and retained ureteral stents accurate determination of the proximal stone burden, preferably by computerized tomography, is important for surgical counseling and planning.
authors.affiliation: Scott Department of Urology, Baylor College of Medicine, Houston, Texas 77030, USA. weedin@bcm.edu
authors.forename: John W
authors.initials: JW
authors.lastname: Weedin
authors.forename: Michael
authors.initials: M
authors.lastname: Coburn
authors.forename: Richard E
authors.initials: RE
authors.lastname: Link
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000601:surgery; D015331:Cohort Studies; D020878:Device Removal; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D053040:Nephrolithiasis / Q000000981:diagnostic imaging / Q000628:therapy*; D009403:Nephrostomy, Percutaneous / Q000009:adverse effects* / Q000379:methods; D011475:Prosthesis Failure; D011860:Radiography, Abdominal; D012189:Retrospective Studies; D015607:Stents / Q000009:adverse effects*; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome; D014514:Ureteral Calculi / Q000000981:diagnostic imaging / Q000628:therapy*; D018666:Ureteroscopy / Q000379:methods; D016482:Urinalysis; D055815:Young Adult