title: Can bedside ultrasound assist in determining whether serum creatinine is elevated in cases of acute urinary retention?
abstract: BACKGROUND
  There are no guidelines to determine which patients with acute urinary retention (AUR) require blood testing (i.e., serum creatinine) to assess for renal failure.
  
  
  OBJECTIVE
  To determine if hydronephrosis on bedside ultrasound correlates with an abnormal serum creatinine (Cr) level in cases of AUR.
  
  
  METHODS
  This was a prospective, observational study of subjects clinically diagnosed with AUR at two associated urban academic centers from October 2004 through August 2006. Emergency physicians completed a data form and performed a bedside ultrasound to determine the presence or absence of hydronephrosis. The data collected included suspected cause of AUR, amount of urinary output after Foley insertion, and blood test results. Follow-up was obtained by telephone and electronic medical record for 1 month. Standard statistics were employed.
  
  
  RESULTS
  Among 96 enrolled subjects with AUR, 43 had a serum Cr level obtained on the initial visit, and 10 (23%; 95% confidence interval [CI] 11-36) of these had an elevated Cr (10% [95% CI 4-16] of the study cohort). The test characteristics of hydronephrosis on bedside ultrasound to detect elevation in Cr were a sensitivity, specificity, positive predictive value, and negative predictive value of 70%, 67%, 39%, and 88%, respectively.
  
  
  CONCLUSIONS
  In cases of AUR, the prevalence of elevated creatinine is high, and hydronephrosis based on bedside ultrasonography does not correlate with elevation in creatinine.
authors.affiliation: Department of Emergency Medicine, St. Luke's-Roosevelt Hospital, New York, New York 10025, USA.
authors.forename: Kaushal
authors.initials: K
authors.lastname: Shah
authors.forename: Jennifer
authors.initials: J
authors.lastname: Teng
authors.forename: Hiral
authors.initials: H
authors.lastname: Shah
authors.forename: Alice
authors.initials: A
authors.lastname: Choe
authors.forename: Amir
authors.initials: A
authors.lastname: Darvish
authors.forename: David
authors.initials: D
authors.lastname: Newman
authors.forename: Dan
authors.initials: D
authors.lastname: Wiener