title: Internal herniation after laparoscopic antecolic Roux-en-Y gastric bypass: a nationwide Danish study based on the Danish National Patient Register.
abstract: BACKGROUND
  Laparoscopic Roux-en-Y gastric bypass (LRYGB) is the most common surgical treatment for morbid obesity in Denmark. Internal herniation (IH) or intermittent internal herniation (IIH) is a major late complication after LRYGB due to persistent mesenteric defects. However, the incidence of IH/IIH is still not known in Denmark.
  
  
  OBJECTIVE
  The primary aim of the study was to assess the incidence of IH/IIH after LRYGB performed in the period between 2006 and 2011 with a follow-up until 2013, where mesenteric defects were not routinely closed during the primary operation.
  
  
  METHODS
  Department of Bariatric Surgery, Koege University Hospital, Denmark
  
  
  METHODS
  We performed a retrospective nationwide analysis of prospectively collected data from all patients with LRYGB performed in Denmark from 2006 to 2011 based on the Danish National Patient Registry (NPR). From January 2006 to December 2011, 12,221 patients underwent an LRYGB procedure in Denmark. Relevant data from all 12,221 patients were retrieved from the NPR during the follow-up period from January 2006 to May 2013; we registered possible subsequent abdominal operations in these patients.
  
  
  RESULTS
  Operations were performed on 398 patients because of suspected IH/IIH; 383 of these patients had IH/IIH (3.1%; 95% CI 2.8-3.5). The estimate for the 5-year cumulative incidence of clinically significant cases with IH/IIH was 4%. The median time interval until the onset of IH/IIH after LRYGB was 15 months (range 0-67 months) in a follow-up period with a median of 38 months (range 16-87 months).
  
  
  CONCLUSIONS
  In the period from 2006 to 2011, mesenteric defects were not routinely closed during LRYGB in Denmark. The cumulative 5-year incidence of IH/IIH after LRYGB was 4% in a median follow-up period of 38 months (range 16-87) in Denmark when data was retrieved from the NPR.
authors.affiliation: Department of Surgery, Koege Hospital, Koege, Denmark; Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. Electronic address: sark@regionsjaelland.dk.
authors.forename: Sara Danshøj
authors.initials: SD
authors.lastname: Kristensen
authors.affiliation: Department of Surgery, Koege Hospital, Koege, Denmark; Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Surgery, Aarhus University Hospital, Aarhus, Denmark; Department of Surgery, Aalborg University Hospital, Aalborg, Denmark.
authors.forename: Per
authors.initials: P
authors.lastname: Jess
authors.affiliation: Department of Surgery, Koege Hospital, Koege, Denmark; Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Andrea Karen
authors.initials: AK
authors.lastname: Floyd
authors.affiliation: Department of Surgery, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Asger
authors.initials: A
authors.lastname: Eller
authors.affiliation: Department of Surgery, Aalborg University Hospital, Aalborg, Denmark.
authors.forename: Anne
authors.initials: A
authors.lastname: Engberg
authors.affiliation: Department of Surgery, Koege Hospital, Koege, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Naver
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D015390:Gastric Bypass / Q000009:adverse effects*; D006547:Hernia / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D015994:Incidence; D010535:Laparoscopy / Q000009:adverse effects*; D008297:Male; D008643:Mesentery; D008875:Middle Aged; D009767:Obesity, Morbid / Q000601:surgery*; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology; D012042:Registries; D012189:Retrospective Studies; D013997:Time Factors; D055815:Young Adult
keywords: Complication; Internal herniation; LRYGB; Mesenteric defects