title: Use of renal ultrasound to detect hydronephrosis after ureteroscopy.
abstract: BACKGROUND
  Ureteral obstruction is a potentially serious complication after ureteroscopy. Postoperative imaging with intravenous urogram and CT has been described as a means to detect asymptomatic or "silent" obstruction. We sought to evaluate the use of renal ultrasound to diagnose hydronephrosis after ureteroscopy in a large, contemporary series.
  
  
  METHODS
  Of the 438 ureteroscopies performed by one staff surgeon at our institution from August 2003 to June 2008, 289 underwent a strict follow-up protocol that included renal ultrasound at approximately 1 month from the date of operation in patients without a stent or 1 month from the date of stent removal in patients with a stent.
  
  
  RESULTS
  Of the 289 patients with proper follow-up, 27 (9.3%) had sonographic evidence of hydronephrosis. Fourteen patients were asymptomatic, and 13 patients experienced ipsilateral flank pain. A total of 4.8% of the patients (14/289) had silent hydronephrosis. The negative predictive value and positive predictive value of ipsilateral flank pain for hydronephrosis were 94% and 35%, respectively. There was no difference between the symptomatic and asymptomatic groups with respect to need for further surgery (38% vs. 21%, p = 0.42). The number of asymptomatic patients after ureteroscopy needing renal ultrasound to diagnose one case of hydronephrosis was 18.
  
  
  CONCLUSIONS
  This study demonstrates that hydronephrosis is present in a small percentage of patients after ureteroscopy. Hydronephrosis can be present in both symptomatic and asymptomatic patients and may warrant further surgery. Renal ultrasonography at 1 month after ureteroscopy permits appropriate detection of hydronephrosis and should be considered as an imaging option.
authors.affiliation: Department of Urology, Boston University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Jules P
authors.initials: JP
authors.lastname: Manger
authors.forename: Pierre J
authors.initials: PJ
authors.lastname: Mendoza
authors.forename: Richard K
authors.initials: RK
authors.lastname: Babayan
authors.forename: David S
authors.initials: DS
authors.lastname: Wang
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006869:Hydronephrosis / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000601:surgery; D007668:Kidney / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care; D016896:Treatment Outcome; D014463:Ultrasonography; D018666:Ureteroscopy / Q000009:adverse effects*