title: Endoscopic transmural necrosectomy for walled-off pancreatic necrosis: a systematic review and meta-analysis.
abstract: BACKGROUND
  Endoscopic transmural necrosectomy (ETN) is emerging as a viable treatment option for walled-off pancreatic necrosis. This NOTES-type procedure is significantly less invasive than an extensive surgical debridement; however, published data regarding the success of ETN in treating pancreatic necrosis have varied.
  
  
  OBJECTIVE
  To evaluate the published medical literature to determine the success of treating walled-off pancreatic necrosis with ETN.
  
  
  METHODS
  Studies using ETN as a primary mode of therapy to treat organized pancreatic necrosis were selected. Success was defined as resolution of the necrotic cavity proven by radiology. Articles were searched in Medline, PubMed, Ovid journals, CINAH, old Medline, Medline nonindexed citations and the Cochrane controlled trials registry. The summary estimates were expressed as pooled proportions. First, the individual study proportions were transformed into a quantity using Freeman-Tukey variant of the arcsine square root transformed proportion. The pooled proportion was calculated as the back-transform of the weighted mean of the transformed proportions, using inverse arcsine variance weights for the fixed-effects model and DerSimonian-Laird weights for the random-effects model. Publication bias was calculated using the Begg-Mazumdar and Harbord bias estimators.
  
  
  RESULTS
  The initial search identified 920 reference articles, of which 129 relevant articles were selected and reviewed. Data were extracted from eight studies (n=233) that met the inclusion criteria. Organization of pancreatic necrosis was determined by computed tomography scan in all of the studies. The mean time of ETN after onset of acute pancreatitis⁄abdominal pain was seven weeks. The weighted mean size of the necrotic cavity was 12.87 cm (95% CI 10.54 cm to 15.20 cm). The weighted mean number of endoscopic procedures needed to resolve the necrotic cavity was 4.09 (95% CI 2.31 to 5.87). Pooled proportion of successful resolution of pancreatic necrosis using ETN was 81.84% (95% CI 76.73% to 86.44%). The pooled proportion of recurrence in the form of necrotic cavity or pseudocyst after ETN was 10.88% (95% CI 7.27% to 15.11%). Complications were noted in 21.33% (95% CI 16.40% to 26.72%) of patients and included bleeding, sepsis and perforation. The weighted mean number of days in hospital after ETN was 32.85 days (95% CI 10.50 to 55.20 days). For pancreatic necrosis that did not resolve, surgery had to be performed in 12.98% (95% CI 9.05% to 17.51%) of patients. The fixed-effect model was used to report all of the pooled proportions. Estimates calculated using fixed- and random-effects models were similar. Test of heterogeneity yielded P>0.10, indicating that the studies could be combined. The publication bias calculated using Begg-Mazumdar bias indicator yielded a Kendall's tau b value of -0.07 (P=0.72) and the same using Harbord bias indicator gave a value of 0.33 (95% CI -1.35 to 2.01; P=0.60). Both of these indicators show that there was no publication bias.
  
  
  CONCLUSIONS
  The present meta-analysis showed that ETN is safe and effective at treating patients with symptomatic walled-off necrosis. ETN offers the advantage of minimally invasive endoscopic treatment without transabdominal surgery; however, better techniques and equipment are still needed to improve procedural efficiency. Decisions to perform ETN should be made by advanced endoscopists in collaboration with a multidisciplinary team with the facilities and personnel to manage these complex patients.
authors.forename: Srinivas R
authors.initials: SR
authors.lastname: Puli
authors.forename: James F
authors.initials: JF
authors.lastname: Graumlich
authors.forename: Smitha R
authors.initials: SR
authors.lastname: Pamulaparthy
authors.forename: Nikhil
authors.initials: N
authors.lastname: Kalva
mesh_terms: D002760:Cholangiopancreatography, Endoscopic Retrograde / Q000379:methods; D002986:Clinical Trials as Topic; D003646:Debridement / Q000379:methods; D019160:Endosonography; D019317:Evidence-Based Medicine; D006801:Humans; D033183:Interdisciplinary Communication; D057605:Natural Orifice Endoscopic Surgery / Q000379:methods; D009336:Necrosis; D010180:Pancreatectomy / Q000379:methods; D010182:Pancreatic Diseases / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D019283:Pancreatitis, Acute Necrotizing / Q000601:surgery; D015203:Reproducibility of Results; D016896:Treatment Outcome