title: Gastric band slippage: a case-controlled study comparing new and old radiographic signs of this important surgical complication.
abstract: OBJECTIVE
  The purpose of this study was to compare the diagnostic performance of four radiographic signs of gastric band slippage: abnormal phi angle, the "O sign," inferior displacement of the superolateral gastric band margin, and presence of an air-fluid level above the gastric band.
  
  
  METHODS
  A search of the electronic medical record identified 21 patients with a surgically proven slipped gastric band and 63 randomly-selected asymptomatic gastric band patients who had undergone barium swallow studies. These studies were evaluated for the four signs of band slippage by two independent radiologists who were blinded to clinical data. Sensitivity, specificity, and positive and negative predictive values were calculated for each radiographic sign of band slippage. Interobserver agreement between radiologists was assessed using the Fleiss kappa statistic.
  
  
  RESULTS
  In evaluating for gastric band slippage, an abnormal phi angle greater than 58° was 91-95% sensitive and 52-62% specific (κ = 0.78), the O sign was 33-48% sensitive but 97% specific (κ = 0.84), inferior displacement of the superolateral band margin by more than 2.4 cm from the diaphragm was 95% sensitive and 97-98% specific (κ = 0.97), and the presence of an air-fluid level was 95% sensitive and 100% specific (κ = 1.00).
  
  
  CONCLUSIONS
  We report two previously undescribed radiographic signs of gastric band slippage that are both sensitive and specific for this important surgical complication and recommend that these signs should be incorporated into the imaging evaluation of gastric band patients.
authors.affiliation: 1 Department of Diagnostic Imaging, Alpert Medical School of Brown University, Rhode Island Hospital, 593 Eddy St, Providence, RI 02903.
authors.forename: David W
authors.initials: DW
authors.lastname: Swenson
authors.forename: Jason A
authors.initials: JA
authors.lastname: Pietryga
authors.forename: David J
authors.initials: DJ
authors.lastname: Grand
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Chang
authors.forename: Brian L
authors.initials: BL
authors.lastname: Murphy
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Egglin
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004867:Equipment Design; D005260:Female; D015391:Gastroplasty / Q000295:instrumentation*; D006801:Humans; D010535:Laparoscopy; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000601:surgery*; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D019736:Prostheses and Implants; D011475:Prosthesis Failure; D011859:Radiography; D012189:Retrospective Studies
keywords: bariatric surgery; barium swallow; gastric band complications; gastric band slippage; laparoscopic adjustable gastric band