GI NOTES

Acute Pancreatitis

1. Causes

Cause	Clues and tests
Gallstones (most common)	Ultrasound; ALT above about 150 U/L early suggests a biliary cause
Alcohol	Usually years of heavy use; ask about smoking too
Hypertriglyceridemia	Triglycerides above 1000 mg/dL (risk rises above 500)
Drugs	Azathioprine, 6-MP, didanosine, valproate, mesalamine, GLP-1 agonists (rare association), others
Post-ERCP	Prevent with rectal indomethacin and pancreatic stents in high-risk cases
Other	Hypercalcemia, autoimmune pancreatitis, trauma, tumors (consider in people over 40), genetic variants
Idiopathic	After a negative work-up, endoscopic ultrasound to look for microlithiasis or a small tumor

2. Severity (revised Atlanta classification)

Grade	Definition
Mild	No organ failure and no local or systemic complications
Moderately severe	Transient organ failure (resolves within 48 hours) and/or local complications or worsening of a chronic illness
Severe	Persistent organ failure lasting more than 48 hours

Early warning signs: SIRS that persists, rising BUN or hematocrit over the first 24 hours, BISAP score of 3 or more, older age, obesity, and pleural effusions. Reassess frequently in the first 48 hours.

3. Early management

• Fluids: lactated Ringer’s; a bolus of about 10 mL/kg if hypovolemic, then about 1.5 mL/kg/hour, adjusted to heart rate, urine output, BUN and hematocrit. The WATERFALL trial showed aggressive fluids caused more overload with no benefit.
• Nutrition: start oral feeding within 24 to 48 hours if tolerated; no need to wait for pain or lipase to normalize. If unable to eat, enteral feeding by nasogastric or nasojejunal tube. Avoid parenteral nutrition unless enteral fails.
• Antibiotics: not for prophylaxis, even in necrotizing pancreatitis. Use them for infected necrosis or another documented infection.
• Pain: multimodal analgesia; opioids are acceptable.
• Hypertriglyceridemia: insulin infusion (with dextrose) lowers triglycerides; plasmapheresis in selected cases. Long-term lipid control prevents recurrence.

4. Gallstone pancreatitis

• ERCP within 24 hours if there is concurrent cholangitis. Without cholangitis or ongoing biliary obstruction, early ERCP does not improve outcomes.
• If a persistent common bile duct stone is suspected, use MRCP or endoscopic ultrasound to decide who needs ERCP.
• Cholecystectomy: during the same admission for mild disease (lowers readmission). In necrotizing pancreatitis, delay until collections resolve or for about 6 weeks.
• Patients unfit for surgery: biliary sphincterotomy reduces recurrent pancreatitis.

5. Local complications

Collection	Timing	Content
Acute peripancreatic fluid collection	Under 4 weeks	Fluid only, no wall
Pseudocyst	4 weeks or more	Fluid with a defined wall
Acute necrotic collection	Under 4 weeks	Fluid and necrotic tissue
Walled-off necrosis	4 weeks or more	Necrosis with a mature wall

• Most collections resolve; asymptomatic collections do not need drainage regardless of size.
• Infected necrosis (gas on CT, or deterioration with no other source): start antibiotics that penetrate necrosis; delay drainage ideally until walled-off (4 weeks or more). Use a step-up approach, with endoscopic transmural drainage preferred.
• Other complications: splenic or portal vein thrombosis, pseudoaneurysm (sudden bleeding: CT angiography and embolization), abdominal compartment syndrome.

6. High-yield pearls

• The degree of lipase elevation does not predict severity; do not trend it daily.
• An early CT (first 72 hours) can underestimate necrosis; save it for unclear diagnosis or a patient not improving.
• Alcohol and smoking cessation counseling should be part of every discharge.
• A first episode in someone over 40 without a clear cause warrants imaging for a pancreatic tumor.

References

• Tenner S, Vege SS, Sheth SG, et al. American College of Gastroenterology Guidelines: Management of Acute Pancreatitis. Am J Gastroenterol. 2024;119(3):419-437.
• Banks PA, Bollen TL, Dervenis C, et al. Classification of acute pancreatitis 2012: revision of the Atlanta classification and definitions by international consensus. Gut. 2013;62(1):102-111.
• de-Madaria E, Buxbaum JL, Maisonneuve P, et al. Aggressive or Moderate Fluid Resuscitation in Acute Pancreatitis (WATERFALL). N Engl J Med. 2022;387(11):989-1000.
• Baron TH, DiMaio CJ, Wang AY, Morgan KA. American Gastroenterological Association Clinical Practice Update: Management of Pancreatic Necrosis. Gastroenterology. 2020;158(1):67-75.

For educational purposes only. This note does not replace clinical judgment or local protocols. Check doses against current labeling and institutional guidance.