Journal name: Clinical and Experimental Gastroenterology Article Designation: REVIEW Year: 2018 Volume: 11 Clinical and Experimental Gastroenterology Dovepress Running head verso: Nahm et al Running head recto: Management of postoperative pancreatic fistula open access to scientific and medical research DOI: http://dx.doi.org/10.2147/CEG.S120217 Open Access Full Text Article REVIEW Postoperative pancreatic fistula: a review of traditional and emerging concepts Christopher B Nahm1–3 Abstract: Postoperative pancreatic fistula (POPF) remains the major cause of morbidity after Saxon J Connor4 pancreatic resection, affecting up to 41% of cases. With the recent development of a consensus Jaswinder S Samra1,2,5 definition of POPF, there has been a large number of reports examining various risk factors, Anubhav Mittal1,2,5 prediction models, and mitigation strategies for this costly complication. Despite these strate- gies, the rates of POPF have not significantly diminished. Here, we review the literature and 1Upper Gastrointestinal Surgical Unit, Royal North Shore Hospital, Sydney, evidence regarding both traditional and emerging concepts in POPF prediction, prevention, and Australia; 2Northern Clinical School, management. In particular, we review the evidence for the association between postoperative Sydney Medical School, The University pancreatitis and POPF, and present a novel proposed mechanism for the development of POPF. of Sydney, Sydney, Australia; 3Bill Walsh Translational Cancer Research Keywords: postoperative pancreatic fistula, postoperative pancreatitis, distal pancreatectomy, Laboratory, Kolling Institute, The pancreaticoduodenectomy University of Sydney, Sydney, Australia; 4Department of Surgery, Christchurch Hospital, Christchurch, New Zealand; Introduction 5Australian Pancreatic Centre, Sydney, Australia Postoperative pancreatic fistula (POPF) remains the main source of major morbidity and mortality after pancreatic resection, affecting between 13% and 41% of patients.1,2 POPF is associated with morbid sequelae including intra-abdominal sepsis and hemor- rhage, carrying a mortality risk of 1% for all patients with POPF and 25% for patients with grade C POPF.3 The development of a POPF results in a complex and lengthy duration of inpatient care with a significant cost burden. Despite numerous reports and trials describing novel methods to curtail the risk of POPF formation, the reported rates of POPF have not significantly improved over the last three decades.4 This is largely attributable to the fact that the underlying mechanism of POPF is poorly understood, with only recent work beginning to reveal the role of postoperative pancreatitis (POP) in the development of POPF, rather than a mere loss of mechanical integrity of the pancreatoenteric anastomosis. Early literature describing POPF has been heterogeneous due to varied definitions of POPF. The development of consensus definitions by the International Study Group on Pancreatic Fistula (ISGPF)5 has allowed for more uniformity in the reporting of this complication. These definitions have been further refined in 2016 to limit the reporting 6 Correspondence: Anubhav Mittal of POPF to only those that impact the postoperative clinical course of the patient. This Upper Gastrointestinal Surgical Unit, has been crucial in allowing valid comparisons to be made between various interven- Level 8A, Acute Services Building, Royal North Shore Hospital, Reserve Road, tions for the prevention and management of this complication. St Leonards, Sydney, NSW 2065, The aim of this review is to discuss both traditional and emerging concepts in the Australia Tel +61 2 9463 2899 understanding of POPF pathophysiology and management, with a focus on potential Email [email protected] future directions for research in this field. submit your manuscript | www.dovepress.com Clinical and Experimental Gastroenterology 2018:11 105–118 105 Dovepress © 2018 Nahm et al. This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms. php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License (http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work http://dx.doi.org/10.2147/CEG.S120217 you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms (https://www.dovepress.com/terms.php). Nahm et al Dovepress Definition of pancreatic fluid. There is a paucity of studies examining Until 2005, there was no consensus in the definition and the precise mechanisms of POPF evolution, although many grading of POPF resulting in an inability to compare various surgical methods to ameliorate this problem have been interventions and preventive techniques for this complication. described, revealing a widespread misunderstanding of This led to great variability in the reported rate of POPF after POPF as a mere loss of mechanical anastomotic integrity. pancreatic resection. An International Working Group of 37 Such reported methods emphasize mechanical buttressing pancreatic surgeons was formed in 2005 to establish for the or reinforcement of the anastomosis or staple line, includ- first time a standardized all-inclusive definition of POPF to ing the use of fibrin sealants,10 autologous tissue patches,11 address this issue. This led to the first widely accepted defi- bioabsorbable mesh,12 varied suturing techniques, 13 stents,14 nition of POPF: “drain output of any measurable volume of and various methods of pancreatoenteric anastomosis.15 fluid on or after postoperative day 3 with an amylase content Very few of these have been consistently demonstrated in greater than 3 times the serum amylase activity.”5 A grading multiple high-volume randomized controlled trials (RCTs) system was also established which stratified patients from a to be effective in significantly reducing the rate or severity relatively benign clinical course (grade A fistula), moderately of POPF.16 unwell patients requiring medical or minimally invasive Many cohort studies have examined and identified risk intervention (grade B), and critically ill patients, often with factors for the development of POPF. The factors most consis- sepsis, requiring invasive intervention (grade C). tently shown to be predictive of POPF after pancreaticoduo- This consensus definition was revised in 2016 mainly denectomy (PD) include soft gland texture, non-pancreatic to restrict the definition of POPF to only those that were cancer non-chronic pancreatitis pathology, small pancreatic “associated with a clinically relevant development/condi- duct diameter (<3 mm), and high intraoperative blood loss tion related directly to the postoperative pancreatic fistula” (>1000 mL). These features may be used to determine the (ie, grade B and C).6 Thus, a grade A POPF has now been Fistula Risk Score (FRS), which is a validated scoring sys- redefined and assigned the term “biochemical leak”, as it tem used to predict the risk of POPF formation after PD.17 does not cause any change to the clinical condition of the Other reported but less-validated risk factors include that of patient. The criteria for defining grade B and C POPFs were increased body mass index (BMI),18 excess intraoperative also made more specific to clarify the distinction between fluid administration,19 increased pancreatic parenchymal the two categories (Table 1). Importantly, this grading sys- remnant volume,20 poor preoperative nutrition,21 and male tem has been repeatedly validated in terms of its association gender.22 The mechanisms by which such preoperative factors with other non-POPF complications,8 length of hospital and lead to POPF have not been studied in detail. intensive care unit (ICU) stay, and the cost of hospital stay.9 Although advanced age is associated with increased peri- operative mortality, there seems not to be an increased risk Traditional concepts of POPF. In a study comparing patients <75 (n=422) and ≥75 Mechanism and risk factors (n=102) years of age undergoing PD, the latter age category The pathophysiology of POPF has been seldom evaluated and was associated with a higher rate of perioperative mortality long assumed to be due to a gradual loss of mechanical integ- (1.9% vs 5.9%, p=0.037), but not associated with increased rity of the pancreatoenteric anastomosis leading to “leakage” risk of POPF (10% vs 7.8%, p=0.579).23 Table 1 2017 ISGPF definitions and grades of postoperative pancreatic fistula6 Event Biochemical leak Grade B POPF Grade C POPF Drain amylase concentration >3× upper limit of normal serum value Yes Yes Yes Persisting peripancreatic drainage >3 weeks No Yes Yes Clinically relevant change in the management of POPF No Yes Yes Percutaneous or endoscopic drainage of POPF-associated collections No Yes Yes Angiographic procedures for POPF-associated bleeding No Yes Yes Reoperation for POPF No No Yes Signs of infection related to POPF No Yes (without organ Yes (with organ failure) failure) POPF-related organ failure No No Yes POPF-related death No No Yes Abbreviations: ISGPF, International Study Group on Pancreatic Fistula; POPF, postoperative pancreatic fistula. 106 submit your manuscript | www.dovepress.com Clinical and Experimental Gastroenterology 2018:11 Dovepress Dovepress Management of postoperative pancreatic