Special Surgery 14. Acute and Chronic Pancreatitis: Symptoms, Diagnosis, Treatment, Complications

I. Acute Pancreatitis

Definition and Etiology

• Acute pancreatitis: acute inflammation of the pancreas
• Cause: premature activation of digestive enzymes → pancreatic autodigestion
• Common causes:

• Cholelithiasis / gallstone pancreatitis
• Alcohol, especially binge drinking
• Post-ERCP pancreatitis
• Hypertriglyceridemia, hypercalcemia, idiopathic
• Drugs: azathioprine, thiazides, valproate, steroids
• Trauma
• Viral infections: mumps, Coxsackie, CMV, HIV

Pathogenesis

• Acinar cell injury or duct obstruction → premature trypsinogen activation
• Activated enzymes → autodigestion + fat necrosis + tissue inflammation
• Cytokine release + vascular injury → vasodilation + increased capillary permeability
• Third spacing → hypovolemia, tachycardia, hypotension → shock
• Untreated hypoperfusion → decreased organ perfusion → multiorgan dysfunction + pancreatic necrosis
• Lipase breaks down fat → free fatty acids bind Ca2+ → hypocalcemia

Classification

1. According to Morphology

• Acute interstitial / edematous pancreatitis: inflammation + pancreatic enlargement, no necrosis, milder
• Acute hemorrhagic / necrotizing pancreatitis: pancreatic or peripancreatic necrosis, higher risk of infection and organ failure

2. According to Severity

• Mild: no organ failure, no local/systemic complications
• Moderately severe: transient organ failure <48 h and/or local complications
• Severe: persistent organ failure >48 h, single or multiple organs

Clinical Features

• Constant severe epigastric pain
• Radiates to the back → belt-like pain
• Worse after meals and when supine
• Improves sitting up / leaning forward
• Nausea, vomiting
• Abdominal tenderness, distension, guarding
• Fever, tachycardia, hypotension in severe disease
• Cullen sign: periumbilical bruising
• Grey-Turner sign: flank discoloration

Diagnosis

• Diagnosis requires 2 of 3 criteria:

1. Typical clinical picture
2. Serum lipase or amylase >= 3x upper limit of normal
3. Imaging consistent with acute pancreatitis

• Labs: lipase/amylase, WBC, CRP, BUN/creatinine, hematocrit, glucose, calcium
• Liver enzymes/bilirubin: ALT rise suggests biliary etiology; ALP/GGT/bilirubin suggest CBD obstruction
• US: evaluate gallstones and biliary duct dilation
• Contrast CT: uncertain diagnosis, broad differential, severe disease, suspected complications or no improvement after 48-72 h
• MRCP/EUS: suspected CBD stone when ERCP indication is uncertain
• ERCP: therapeutic; urgent only with cholangitis or persistent biliary obstruction
• Severity assessment: organ failure, SIRS/shock, BUN/hematocrit trend; scores such as BISAP/Ranson can support risk assessment

II. Acute Pancreatitis: Treatment and Complications

Initial Treatment

• Hospital admission, severity assessment, monitor vital signs and urine output
• Early IV fluid replacement in first 24 h: Ringer lactate or normal saline, goal-directed
• Pain control: opioids often required; NSAIDs in selected mild cases if safe
• Antiemetics, oxygen, electrolyte correction
• ICU if persistent organ failure, shock, respiratory failure or severe SIRS

Nutrition and Antibiotics

• Mild pancreatitis: restart oral feeding early when pain/nausea decrease; prolonged NPO is not needed
• Moderately severe/severe pancreatitis: enteral feeding preferred
• Enteral route: nasogastric or nasojejunal tube
• Parenteral nutrition only if enteral feeding is impossible or inadequate
• No prophylactic antibiotics for sterile necrosis or predicted severe pancreatitis
• Antibiotics only if infection is suspected/proven:

• Cholangitis
• Infected pancreatic necrosis
• Extrapancreatic infection: pneumonia, UTI, bacteremia, catheter infection

Treat the Cause

• Gallstone pancreatitis:

• Urgent ERCP only if cholangitis or persistent biliary obstruction
• Mild disease → laparoscopic cholecystectomy during same admission after clinical improvement
• Severe disease → delay cholecystectomy until inflammation/collections stabilize

• Alcohol: abstinence support, withdrawal prevention
• Hypertriglyceridemia: acute triglyceride-lowering treatment in selected severe cases, then long-term lipid control
• Drug-induced: stop causative drug
• Hypercalcemia: treat underlying cause

Interventional / Surgical Treatment

• Stable necrotizing pancreatitis: delay intervention if possible, ideally until collection wall matures around 4 weeks
• Indications:

• Infected necrosis with sepsis or deterioration
• Symptomatic walled-off necrosis or pseudocyst
• Abdominal compartment syndrome
• Ongoing acute bleeding / pseudoaneurysm
• Bowel ischemia/perforation
• Obstruction due to mass effect

• Step-up approach:

• Antibiotics + supportive care if infected necrosis suspected
• Percutaneous catheter drainage or endoscopic transmural drainage
• Minimally invasive necrosectomy if drainage fails
• Open necrosectomy only if less invasive methods fail or emergency indication exists

Complications

1. Local Complications

• Pancreatic/peripancreatic necrosis: sterile or infected
• Pancreatic pseudocyst
• Pancreatic abscess / infected collection
• Hemorrhage / pseudoaneurysm
• Pancreatic ascites, pleural effusion
• Gastric outlet, biliary or bowel obstruction from mass effect

2. Systemic Complications

• SIRS / sepsis
• Shock
• ARDS
• Acute kidney injury
• DIC
• Hypocalcemia
• Hyperglycemia / diabetes mellitus
• Multiorgan failure

III. Chronic Pancreatitis

Definition and Etiology

• Chronic pancreatitis: recurrent/long-standing pancreatic inflammation
• Pancreatic parenchyma is replaced by fibrotic connective tissue
• Progressive exocrine and endocrine pancreatic insufficiency
• Etiology:

• Chronic alcohol use
• Smoking
• Recurrent acute pancreatitis
• Idiopathic
• Autoimmune pancreatitis
• Hereditary/genetic: PRSS1, SPINK1, CFTR
• Pancreatic duct obstruction: stone, stricture, tumor

Pathomechanism

• Acinar cell damage + pancreatic outflow obstruction
• Premature trypsinogen activation → intrapancreatic enzyme activation
• Autodigestion + recurrent inflammation
• Toxins/inflammatory mediators activate pancreatic stellate cells → fibrosis
• Fibrosis + duct distortion + calcification → chronic pain and obstruction
• Loss of acinar cells → exocrine insufficiency
• Loss of islet cells → endocrine insufficiency / diabetes mellitus

Clinical Features

• Chronic epigastric pain
• Radiates to the back → belt-like
• Worse after meals and when supine; improves leaning forward
• Initially episodic, later persistent
• Nausea, vomiting
• Jaundice if distal CBD stricture/compression
• Exocrine insufficiency: malabsorption, steatorrhea, weight loss, fat-soluble vitamin deficiency
• Endocrine insufficiency: diabetes mellitus

Diagnosis

• Diagnosis: clinical features + imaging + functional assessment
• Labs: pancreatic enzymes can be normal in advanced disease; bilirubin/liver enzymes if obstruction; glucose/HbA1c for endocrine function
• Fecal elastase: low in exocrine pancreatic insufficiency
• CT/MRI: calcifications, atrophy, duct dilation, pseudocyst
• MRCP: ductal abnormalities, stones, strictures
• Endoscopic US: sensitive for early disease and helps exclude tumor
• ERCP: mainly therapeutic, not routine diagnostic

Complications

• Pancreatic insufficiency: exocrine malabsorption + endocrine diabetes mellitus
• Pancreatic pseudocyst
• Biliary or duodenal obstruction
• Bleeding / pseudoaneurysm
• Pancreatic ascites
• Splenic vein thrombosis
• Increased risk of pancreatic cancer

IV. Chronic Pancreatitis: Treatment and Surgical Aspects

Conservative and Endoscopic Treatment

• Alcohol cessation and smoking cessation
• Nutritional support: high-calorie diet if weight loss; avoid severe fat restriction if malnutrition worsens
• Fat-soluble vitamin replacement: A, D, E, K if deficient
• Pancreatic enzyme replacement: steatorrhea, weight loss or low fecal elastase with symptoms
• Pain management: NSAIDs/paracetamol if safe → opioids only if needed; treat structural pain cause
• Diabetes treatment: often insulin, monitor hypoglycemia risk
• Endoscopic treatment:

• Pancreatic duct stenting / stone extraction for painful duct obstruction
• Pseudocyst drainage if symptomatic and accessible
• Biliary stenting for benign distal bile duct stricture

Surgical Indications

• Intractable pain despite conservative/endoscopic treatment
• Dilated pancreatic duct with obstructing stones/strictures
• Symptomatic pseudocyst
• Biliary or duodenal obstruction
• Bleeding complication not controlled by radiology/endoscopy
• Suspicion of pancreatic cancer

Surgical Procedures

• Drainage procedure:

• Puestow / Partington-Rochelle: longitudinal pancreaticojejunostomy
• Indication: pain with dilated main pancreatic duct, without dominant head mass

• Resection procedures:

• Whipple procedure / pancreaticoduodenectomy: pancreatic head disease, suspected malignancy, biliary/duodenal obstruction
• Distal pancreatectomy: isolated body/tail disease or suspected distal tumor

• Hybrid / duodenum-preserving procedures:

• Frey: pancreatic head coring + longitudinal pancreaticojejunostomy
• Beger: duodenum-preserving pancreatic head resection

• Total pancreatectomy: last resort only; not routine for pain because it causes brittle diabetes and complete exocrine insufficiency