Classification of acute pancreatitis 2012 Revision of the Atlanta classification and definitions

Summary of the 1992 Atlanta Classification British Journal of Surgery 2008; 95: 6–21

New findings Criteria for the diagnosis of acute pancreatitis Two types of acute pancreatitis –Interstitial edematous pancreatitis –Necrotising pancreatitis Severity –Mild, Moderately severe, severe Definition of pancreatic and peripancreatic collectioins New information of etiology, pathophysiology, radiologic description Differentiates acute peripancreatic fluid, pancreatic pseudocyst, acute necrotic collection and walled-off necrosis

Revised definitions and classification of acute pancreatitis Diagnosis of acute pancreatitis (two of three) 1.Abdominal pain : acute onset of a persistent, severe, epigastric pain often radiating to the back 2.Serum lipase or amylase : ≥3 x upper limit of normal 3.Characteristic findings of imaging study : contrast-enhanced computed tomography (CECT), magnetic resonance imaging (MRI) or ultrasonography Onset of acute pancreatitis Time of onset of abdominal pain

Types of acute pancreatitis : Interstitial edematous pancreatitis and Necrotising pancreatitis Definition of types of acute pancreatitis Interstitial edematous pancreatitis Acute inflammation of the pancreatic parenchyma and peripancreatic tissues, No tissue necrosis CECT criteria ▸ Pancreatic parenchyma enhancement by IV contrast ▸ No findings of peripancreatic necrosis Diffuse (or occasionally localised) enlargement Relatively homogeneous enhancement Peripancreatic fat : haziness or mild stranding Peripancreatic collections

Interstitial edematous pancreatitis

Necrotising pancreatitis Inflammation associated with pancreatic parenchymal necrosis and/or peripancreatic necrosis CECT criteria ▸ Lack of pancreatic parenchymal enhancement by IV contrast ▸ Presence of peripancreatic necrosis Parenchymal (<5%), peripancreatic (20%), both (75~80%) Evolve over several days : Peripancreatic necrosis  pancreatic parenchyma % of pancreatitis Increased morbidity and intervention rate Sakorafas et al. J Am Coll Surg 1999;188(6):643–648. Spanier et al. Pancreatology 2010;10:222–8.

Necrotising pancreatitis

Infected pancreatic necrosis Sterile Necrosis  Infected (no correlation with extent of necrosis) Rare during the first week Increase morbidity and mortality Need for antibiotics and active intervention Extraluminal gas in the pancreatic and/or peripancreatic tissue on CT Positive culture on FNA In original Atlanta Classification : “pancreatic abscess - localised collection of purulent material without significant necrotic material Van Santvoort et al.Gastroenterology 2011;141:1254–63.

Infected pancreatic necrosis

Organ failure –Repiratory, cardiovascular and renal system Local complications –Acute peripancreatic fluid collection, pancreatic pseudocyst, acute necrotic collection and walled-off necrosis Systemic complications –Exacerbation of pre-existing co-morbidity Complications of acute pancreatitis

Organ failure Modified Marshall scoring system for organ dysfunction (≥2) Marshall et al. Crit Care Med 1995;23:1638–52.

Intensive Care Med 1996;22:707–10.

Local complication Acute peripancreatic fluid collection, Pancreatic pseudocyst, Acute necrotic collection and Walled-off necrosis Other local complication (acute pancreatitis include gastric outlet dysfunction, splenic and portal vein thrombosis, and colonic necrosis) When suspect?? –Persistence or recurrence of abdominal pain, secondary pancreatic enzyme increase, increasing organ dysfunction, clinical sign of sepsis  imaging study Location, nature of content, thickness of any wall, impaired perfusion

Systemic complication Exacerbation of pre-existing co-morbidity –coronary artery disease –chronic lung disease Persistent organ failure vs other systemic complication

Phases of acute pancreatitis Early phase (1 st week) Host reponse due to local pancreatic injury Pancreatic inflammation  Cytokine cascades  Systemic inflammatory response syndrome (SIRS) Persistent SIRS  Organ failure : severity in early phase ‘Transient organ failure’ : ≤ 48h ‘Persistent organ failure’ : > 48h Mofidi et al. Br J Surg 2006;93:738–44. Singh et al. Clin Gastroenterol Hepatol 2009;7:1247–51.

Late phase (weeks to months) Persistence of systemic sign of inflammation Presence of local complications Moderately severe or Severe acute pancreatitis Local complication : important for management Persistent organ failure : severity

Severity of acute pancreatitis Mild, moderately severe, severe : Transient or persistent organ failure, local or systemic complication 1.Potential require aggressive early treatment 2.Identify transfer to specialist care 3.Advantage to stratifying subgroups (organ failure, local or systemic complication)

Mild acute pancreatitis –No organ failure –No local or systemic complication –Discharged during the early phase –Do not require pancreatic imaging Moderately severe acute pancreatitis –Transient organ failure –Local or systemic complications without persistent organ failure –Resolve without intervention ~ prolonged specialist care Severe acute pancreatitis –Persistent organ failure (single ~ multiple) –Mortality : 36~50% (extremely high with infected necrosis) Petrov et al. Gastroenterology 2010;139:813–20.

Evolution of severity of acute pancreatitis Reassessed according to organ failure Time points : 24h, 48h and 7days In early phase : Local complications not necessary to document –After 5~7 days CT is more reliable –Not directly proportion to severity, –No treatments are require at first week In the late phase : local complications is more important (infected necrosis)  local complications (absent, sterile or infected), persistent organ failure (single or multiple) Petrov et al. Am J Gastroenterol 2010;105:74–6.

Definition of pancreatic and peripancreatic collections Interstitial edematous pancreatitis Acute peripancreatic fluid collection (APFC) Pancreatic pseudocyst (>4weeks) Necrotising pancreatitis Acute necrotic collection (ANC) Walled–off necrosis (WON)

Acute peripancreatic fluid collection (APFCs) Interstitial edematous pancreatitis ≤4 weeks Without the features of a pseudocyst Sterile, resolve without intervention CECT criteria ▸ Homogeneous collection with fluid density ▸ Confined by normal peripancreatic fascial planes ▸ No definable wall encapsulating the collection ▸ Adjacent to pancreas (no intrapancreatic extension)

Acute peripancreatic fluid collection (APFCs)

Pancreatic psueodcyst Encapsulated collection of fluid, well defined inflammatory wall Outside the pancreas with minimal or no necrosis. >4 weeks Aspiration of cyst content : amylase↑ Disruption of the main pancreatic duct or branches CECT criteria ▸ Well circumscribed, usually round or oval ▸ Homogeneous fluid density ▸ No non-liquid component

Pancreatic pseudocyst

Acute necrotic collection (ANC) Necrotising pancreatitis Containing variable amounts of fluid and necrosis Involve the pancreatic parenchyma and/or the peripancreatic tissues ≤4 weeks, may be multiple and loculated Can become infected CECT criteria ▸ Heterogeneous and non-liquid density of varying degrees in different locations ▸ No definable wall encapsulating the collection ▸ Location : intrapancreatic and/or extrapancreatic

Acute necrotic collection (ANC)

Walled-off necrosis (WON) Mature, encapsulated collection of pancreatic and/or peripancreatic necrosis >4 weeks, May be multiple, distant from the pancreas Can become infected Previously : organised pancreatic necrosis, necroma, pancreatic sequestration, pseudocyst associated with necrosis, subacute pancretic necrosis MRI, abdominal US, EUS is better than CT CECT criteria ▸ Heterogeneous with liquid and non-liquid density with varying degrees of loculations ▸ Completely encapsulated Well defined wall ▸ Location : intrapancreatic and/or extrapancreatic

Walled-off necrosis (WON)

Treatment Interstitial edematous pancreatitis (IEP) Self-limited, and supportive care APFC : resolve spontaneously or mature into pseudocysts Pseudocyst : 25% become symptomatic or infected and necessitate drainage Infected pseudocysts – bubbles on CT, FNA for definitive diagnosis Percutaneous drain > surgical drain Endoscopic drain : mature wall, in proximity to the gastrointestinal lumen, not in infected case Habashi et al. World J Gastroenterol 2009;15(1): 38–47. Seewald et al. Dig Endosc 2009;21(1):S61–S65.

Necrotizing pancreatitis Minimally invasive radiologic procedure, laparoscopic, endoscopic or surgical technique CT severity index, Modified CT severity index No treatment algorithm Early surgical debridement (58%)  supportive therapy (27%) Ix. Of surgery : >1month, persistent symptom Severe course of complication : percutaneous drainage Modified CT severity index CT severity index Mortele et al. Am J Roentgenol 2009;192(1):110–116.

Sterile pancreatic necrosis CT every 7-10 days : necrosis, infection, hemorrhage Clinical instability without radiologic evidence of infection  FNA No clinical study : fine-needle sampling vs indwelling catheter Lack of improvement Pancreatic duct disruption, additional peripancreatic necrotic collection  Supportive care and percutaneous drainage (controversial : infection vs complete drainage) Cardiovasc Intervent Radiol 2004;27(6):567–580.

Infected pancreatic necrosis Presence of gas in the CT High morbidity and mortality Surgical debridement and antibiotics Primary open necrosectomy vs Percutaneous catheter drainage, endoscopic catheter drainage, minimally invasive necrosectomy Van Santovoort et al. N Engl J Med 2010;362(16):1491–1502.

Recent modified procedure Introduction of percutaneous catheter  single large-port laparoscope for necrosectomy Bucher et al. Pancreas 2008;36(2):113–119. Percutaneous puncture and catheterization  Choledochoscope- guided debridement Tang et la. World J Gastroenterol 2010;16(4):513–517.

Summury Diagnosis : Symptom, Enzyme, Imaging (2 of 3) Type –Interstitial edematous pancreatitis –Necrotising pancreatitis Complication –Oragan failure –Local & systemic complicatoin Phase : Early (≤ 1weeks), Late (weeks to months) Severity : Mild, Moderately severe, Severe

Fluid collections in acute pancreatitis