Can you summarize acute pancreatitis?

Acute Pancreatitis: Evidence-Based Summary

Definition and Diagnosis

Acute pancreatitis requires at least two of three criteria: (1) abdominal pain consistent with the disease, (2) serum amylase and/or lipase greater than three times the upper limit of normal, and (3) characteristic findings on abdominal imaging. 1, 2 Lipase is preferred over amylase when available due to superior diagnostic accuracy. 2

• Diagnosis should be established within 48 hours of admission in all patients 1
• When diagnosis remains uncertain after clinical and biochemical assessment, contrast-enhanced CT provides definitive evidence 2

Severity Classification

The Revised Atlanta Classification stratifies acute pancreatitis into three severity levels based on the presence and duration of organ failure:

Mild Acute Pancreatitis

• No organ failure, no local or systemic complications 1, 2
• Mortality <1–3% 1
• Characterized by interstitial edema of the pancreas 2
• Usually resolves within the first week 2

Moderately Severe Acute Pancreatitis

• Transient organ failure (<48 hours) and/or local complications 1, 2
• May involve exacerbation of comorbid disease 2

Severe Acute Pancreatitis

• Persistent organ failure (>48 hours) affecting cardiovascular, respiratory, and/or renal systems 1, 2
• Mortality ranges from 13% to 35% 1
• Patients with persistent organ failure AND infected necrosis have the highest mortality risk at 35.2% 2, 3
• Infected necrosis without organ failure carries only 1.4% mortality 2, 3

Critical pitfall: Patients must be observed for at least 48 hours to differentiate transient from persistent organ failure—premature classification leads to inappropriate triage. 2

Early Assessment and Risk Stratification

All patients require severity stratification within 48 hours of admission using validated scoring systems. 1, 2

• APACHE II score ≥8 (or ≥9 in some guidelines) indicates severe disease 1, 2
• Glasgow score ≥3 criteria indicates severe disease (requires 48 hours to complete) 2
• C-reactive protein >150 mg/L indicates severity 2
• Body mass index >30 serves as an additional severity marker 2
• Persistent SIRS (systemic inflammatory response syndrome) confers 25.4% mortality versus 8% with transient SIRS 3

Clinical assessment alone misclassifies approximately 50% of patients and should never be used in isolation. 2

Imaging Strategy

Initial Imaging

• Abdominal ultrasound should be performed on admission to identify biliary etiology 1, 2

Severity Assessment Imaging

• Contrast-enhanced CT (or MRI) is recommended for all patients with severe acute pancreatitis, optimally performed 72–96 hours after symptom onset 1, 2
• Performing CT before 72 hours may underestimate the true extent of necrosis 2
• Dynamic CT should be obtained between days 3–10 in all patients with predicted severe disease 1, 2

Initial Management

Fluid Resuscitation

Goal-directed fluid therapy is recommended, though the choice between normal saline and Ringer's lactate remains unresolved. 1

• Hydroxyethyl starch (HES) fluids should be avoided—they increase multiple organ failure (OR 3.86) without mortality benefit 1

Nutritional Support

Early oral feeding within 24 hours is strongly recommended as tolerated, rather than keeping patients nil per os. 1

• When oral feeding is not possible, enteral nutrition is strongly preferred over parenteral nutrition 1
• For patients requiring tube feeding, either nasogastric or nasojejunal routes are acceptable 1

Antibiotic Prophylaxis

Prophylactic antibiotics are NOT recommended in predicted severe or necrotizing pancreatitis. 1

• Meta-analyses after 2002 show no reduction in infected necrosis (OR 0.81) or mortality (OR 0.85) 1
• Antibiotics should be reserved for documented or strongly suspected infection 1

Intensive Care Management

All patients with persistent organ failure should be admitted to an intensive care unit for full organ-system support. 1, 2

• Cardiovascular, respiratory, and renal support as needed 1, 2
• Patients with moderately severe disease and transient organ failure should be considered for high-dependency unit admission 2

Etiology-Specific Management

Biliary Pancreatitis

For acute biliary pancreatitis without cholangitis or common bile duct obstruction, routine urgent ERCP is NOT recommended. 1

• ERCP with sphincterotomy is indicated when cholangitis or biliary obstruction is present 1
• Cholecystectomy should be performed during the initial admission in mild disease 1
• For severe/necrotizing biliary pancreatitis, cholecystectomy should occur ideally within 2 weeks and no later than 4 weeks after onset 1, 2

Alcohol-Related Pancreatitis

Brief alcohol intervention counseling should be provided during admission. 1

Local Complications and Their Management

Timing-Based Classification

• Acute peripancreatic fluid collections: occur early (first week), lack a defined wall 2
• Acute necrotic collections: develop within first 4 weeks, contain mixed fluid and necrotic debris without mature wall 2
• Pseudocyst: requires ≥4 weeks to form, encapsulated collection with fibrous/granulation tissue wall 2
• Walled-off necrosis (WON): matures ≥4 weeks, encapsulated necrotic collection with well-defined enhancing wall 1, 2

Indications for Intervention

Clinical deterioration with signs or strong suspicion of infected necrotizing pancreatitis mandates intervention (percutaneous/endoscopic drainage). 1

After 4 weeks from onset, intervention is indicated for:

• Ongoing organ failure without signs of infected necrosis 1
• Gastric outlet, biliary, or intestinal obstruction from large WON 1
• Disconnected duct syndrome 1
• Symptomatic or growing pseudocyst 1

After 8 weeks from onset:

• Ongoing pain and/or discomfort 1

Intervention Strategy

A step-up approach starting with percutaneous or endoscopic drainage is preferred over immediate surgery. 1

• Surgical intervention is reserved for failure of percutaneous/endoscopic approaches, abdominal compartment syndrome unresponsive to conservative measures, uncontrolled bleeding when endovascular approach fails, bowel ischemia, acute necrotizing cholecystitis, or bowel fistula into peripancreatic collection 1
• Postponing surgical interventions for more than 4 weeks after disease onset reduces mortality 1

Infection of Necrosis

• Infection typically occurs 7–14 days after disease onset 3
• Clinical indicators include sudden high fever, increasing leukocyte and platelet counts, and deranged clotting parameters 3
• Infected necrosis triples mortality risk 2
• A small number of patients with infected necrosis may recover with antibiotics alone, though most require intervention 1

Prognosis and Outcomes

• Overall mortality should be <10%, and <30% in severe cases 1, 2
• Persistent organ failure is the strongest predictor of mortality 3
• Patients with sterile necrosis and organ failure have approximately 19.8% mortality 2
• Acute fluid collections develop in 30–50% of patients with severe pancreatitis 3
• Having three or more fluid collections significantly increases risk of complications and death 3