title: EUS for suspected choledocholithiasis: do benefits outweigh costs? A prospective, controlled study.
abstract: BACKGROUND
  This prospective study of the use of EUS to prevent unnecessary endoscopic retrograde cholangiography in patients with suspected choledocholithiasis has two aims: to evaluate the effectiveness, based on patient outcome, and the potential clinical and economic benefits of EUS.
  
  
  METHODS
  A prospective series of 485 patients (202 men, 283 women; mean age 66.2 years, range 20-94 years) suspected to have choledocholithiasis based on clinical, biochemical, and cross-sectional imaging (US or CT) data underwent EUS. Positive EUS findings were confirmed by endoscopic retrograde cholangiography with sphincterotomy and/or by surgery; negative findings were confirmed by clinical follow-up. An EUS result was considered a true negative if the patient was confirmed symptom-free with normal tests on follow-up of at least 6 months. The costs of EUS (procedure, days of hospitalization, any morbidity) were compared with the estimated costs of the endoscopic retrograde cholangiography avoided in patients with true-negative EUS findings.
  
  
  RESULTS
  EUS findings were verified in 463 patients: EUS diagnosed choledocholithiasis in 239 (51.6%) and the absence of stones in 220 patients. In 4 patients (0.8%), EUS was incomplete. By sphincterotomy (209 patients), surgical bile duct exploration (39), percutaneous cholangiography (1 case in which EUS demonstrated a bile duct tumor), and follow-up (214), EUS diagnoses were confirmed as follows: 237 true-positive, 216 true-negative, 2 false-positive, 4 false-negative, 4 incomplete (sensitivity 98%, specificity 99%, positive predictive value 99%, negative predictive value 98%, accuracy 97%). In 214 (46%) patients, more invasive investigations of the bile duct were avoided. The mean cost for patients managed by the EUS-based strategy was ' 374.50 (-284.72), which was significantly less than the theoretical mean cost of ' 443.80 (p < 0.001) for patients undergoing endoscopic retrograde cholangiography.
  
  
  CONCLUSIONS
  The results of this study confirm that EUS is highly reliable for the diagnosis of choledocholithiasis. Its use offers considerable clinical and economic advantages by preventing inappropriate and more invasive evaluation of the bile duct.
authors.affiliation: Gastroenterology Department, Ospedale Maggiore, Crema, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Buscarini
authors.forename: Paolo
authors.initials: P
authors.lastname: Tansini
authors.forename: Daniele
authors.initials: D
authors.lastname: Vallisa
authors.forename: Alessandro
authors.initials: A
authors.lastname: Zambelli
authors.forename: Luigi
authors.initials: L
authors.lastname: Buscarini
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002760:Cholangiopancreatography, Endoscopic Retrograde; D003365:Costs and Cost Analysis; D019160:Endosonography; D005260:Female; D042882:Gallstones / Q000000981:diagnostic imaging*; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016896:Treatment Outcome