title: EUS characteristics of Nissen fundoplication: normal appearance and mechanisms of failure.
abstract: BACKGROUND
  In patients who develop symptoms after Nissen fundoplication, the precise mechanism of failure can be difficult to determine. Current testing modalities do not demonstrate sufficient anatomic detail to definitively determine the mechanism. This observational study establishes that EUS can determine fundoplication integrity and hiatal anatomic relationships after Nissen fundoplication.
  
  
  METHODS
  EUS was performed on the native esophagogastric junction and after Nissen fundoplication in two swine. The EUS characteristics of a properly performed fundoplication were determined. Subsequently, complications of Nissen fundoplication were created, and EUS was performed on each. The EUS criteria of each mechanism of failure were defined.
  
  
  RESULTS
  EUS provided sufficient axial resolution to distinguish the esophagus, the fundoplication, and the surrounding hiatal structures within a single image. US of the native esophagogastric junction discerned the length of intra-abdominal esophagus, esophagogastric junction, crura, and anterior hiatus, and, thus, the point of entry into the abdominal cavity. EUS of Nissen fundoplication revealed a 5-layered pattern in a 360 degree configuration. These layers represent the following: (1) the esophageal wall, (2) the space between the esophagus and the fundoplication, (3) the inner gastric wall of the fundoplication, (4) the gastric lumen, and (5) the outer gastric wall of the fundoplication. A slipped repair was identified by the presence of an echogenic gastric serosa within the fundoplication. A tight fundoplication results in attenuation of the gastric walls, thickening of the esophageal wall, and loss of the 5-layer pattern secondary to obliteration of the potential spaces of the gastric lumen. Dehiscence of the fundoplication was evidenced by a less than 360 degree 5-layer pattern.
  
  
  CONCLUSIONS
  EUS of hiatal anatomic relationships is feasible and provides detailed information regarding the integrity and the position of a Nissen fundoplication. EUS may enable a precise determination of the anatomic causes of failure after antireflux surgery.
authors.affiliation: Section of Gastroenterology and Hepatology, University of Wisconsin-Hospitals and Clinics, Madison, Wisconsin, USA.
authors.forename: Deepak V
authors.initials: DV
authors.lastname: Gopal
authors.forename: Eugene Y
authors.initials: EY
authors.lastname: Chang
authors.forename: Charles Y
authors.initials: CY
authors.lastname: Kim
authors.forename: Corinne
authors.initials: C
authors.lastname: Sandone
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Pfau
authors.forename: Terrence J
authors.initials: TJ
authors.lastname: Frick
authors.forename: John G
authors.initials: JG
authors.lastname: Hunter
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Kahrilas
authors.forename: Blair A
authors.initials: BA
authors.lastname: Jobe
mesh_terms: D000818:Animals; D019160:Endosonography; D004943:Esophagogastric Junction / Q000473:pathology*; D018662:Fundoplication; D011183:Postoperative Complications; D013552:Swine; D017211:Treatment Failure