An overview of walled-off pancreatic necrosis for clinicians

ABSTRACT

Introduction: Walled of pancreatic necrosis (WOPN) is a new term coined for encapsulated fluid collection developing after acute necrotising pancreatitis (ANP). It is a heterogeneous collection containing varying amount of liquid as well as solid necrotic material. The literature on its natural history as well as appropriate management is gradually expanding thereby improving treatment outcomes of this enigmatic disease.

Areas covered: This review discusses currently available literature on etiology, frequency, natural history, and imaging features WOPN. Also, updated treatment options including endoscopic, radiological and surgical drainage are discussed.

Expert opinion: WOPN is alocal complication of ANP occurring in the delayed phase of ANP and may be asymptomatic (50%) or present with pain, fever, jaundice, or gastric outlet obstruction. Natural courses of asymptomatic WOPN have been infrequently studied, and it appears that the majority remain asymptomatic and resolve spontaneously. Magnetic resonance imaging and endoscopic ultrasound are the best imaging modalities to evaluate solid necrotic debris. Symptomatic WOPN usually needs immediate drainage, this can be done endoscopically, radiologically, or surgically. Current evidence suggests that endoscopic transluminal drainage is the preferred drainage technique as it is effective and associated with lower mortality, risk of organ failure, adverse effects, and length of hospital stay.

KEYWORDS:

• Acute pancreatitis
• disconnected pancreatic duct syndrome
• stent
• fistula
• endosonography
• magnetic resonance imaging
• necrosis

Article highlights

• WOPN is an encapsulated collection of liquid and solid necrotic material that develops in delayed phase (usually after 4 weeks) of acute necrotizing pancreatitis. CECT is the most commonly used image modality to diagnose WOPN. However, EUS and MRI can better evaluate the content of WOPN by accurately identifying the solid necrotic content. The role of DW-MRI in detecting infection in pancreatic fluid collections is promising and need further evaluation.

• Majority of patients with asymptomatic WOPN have an uneventful course with spontaneous recovery. However, one-third of patients with asymptomatic WOPN will develop complications. The factors that can predict symptoms or complications in asymptomatic WOPN are currently now known.

• Since the advent of minimally invasive surgical and endoscopic techniques, the role of open surgery has diminished. The choice of surgical technique depends upon the location of WOPN with WOPN located in lesser sac usually treated with transgastric necrosectomy where necrosis located in the para-colic gutters best approached by VARD.

• Inability to reliably remove the solid necrotic debris is one of the major limitations of percutaneous drainage. Although easier to place, percutaneous drainage is associated with increased risk of external fistula formation, re-interventions, discomfort, risk of accidental slippage, and prolonged hospital stay.

• Recent studies including randomized controlled studies have shown that endoscopic drainage is associated with lower mortality and adverse effects in comparison to minimally invasive surgical techniques, and therefore, WOPN located adjacent to gastro-duodenal lumen should be treated endoscopically, whenever the expertise is available.

• There is probably no significant difference in outcome between LAMS and multiple plastic stents. However, LAMS is technically easier to insert in a shorter procedure time as compared to plastic stents and also avoids large diameter balloon dilatation and therefore may be preferred over plastic stents.

• Recent reports about increased risk of bleeding with LAMS have raised concerns about leaving LAMS for longer duration. Shorter duration (<3 weeks) of LAMS placement seems to be associated with similar high success rates without serious adverse effects.

• DEN is an effective procedure for removing solid necrotic debris, but its exact role in clinical practice needs to be defined.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

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Funding

This paper was not funded.