Pancreatitis - Complete Overview

Definition

• Acute pancreatitis - reversible if the cause is removed
• Chronic pancreatitis - irreversible destruction of exocrine (and eventually endocrine) pancreas

Anatomy Recap

ACUTE PANCREATITIS

Epidemiology

• Incidence: 33-74 per 100,000 globally; 5-35 per 100,000 in the West
• Overall mortality ~5%; up to 30% in severe cases
• Incidence rising due to obesity epidemic and gallstone disease

Causes (mnemonic: GET SMASHED)

• Idiopathic: 10-20% (many due to occult microlithiasis or CFTR/PRSS1/SPINK1 mutations)
• Smoking and diabetes are independent risk factors

Pathophysiology

1. Inciting event (duct obstruction, toxin) → disrupts normal membrane trafficking
2. Inappropriate activation of trypsinogen → excess trypsin
3. Trypsin activates other digestive enzymes → autodigestion of pancreatic tissue
4. Macrophage/neutrophil recruitment, cytokine release → increased vascular permeability
5. Edema, hemorrhage, necrosis
6. If severe: SIRS → sepsis, shock, multiorgan failure
7. Bacterial translocation from intestinal flora → bacteremia

Clinical Features

• Persistent, moderate-to-severe epigastric or LUQ pain radiating to the back (classic)
• Pain relieved by leaning forward/sitting up
• Nausea, vomiting, anorexia
• Oral intake worsens pain

• Fever, tachycardia
• Epigastric tenderness ± guarding
• Diminished bowel sounds (ileus)
• Jaundice if obstructive cause
• Cullen sign - periumbilical bruising (hemoperitoneum) - rare, poor prognosis
• Grey Turner sign - flank bruising (retroperitoneal bleeding) - rare, poor prognosis
• Murphy sign if gallstone cause

Diagnosis

• Degree of enzyme elevation does NOT correlate with severity

• NOT routinely needed for diagnosis
• CT with IV contrast indicated for:
  1. Diagnostic uncertainty
  2. Rule out other pathology
  3. Assess complications if not improving after 48-72 hours
• CT findings of necrosis often not seen early - most useful at 3-7 days
• CT is normal in 15% of acute pancreatitis cases
• MRI/MRCP: better for duct anatomy, preferred in renal failure or contrast allergy

• Ranson criteria (on admission and 48h)
• BISAP score (BUN, Impaired mental status, SIRS, Age >60, Pleural effusion)
• APACHE II
• CT Severity Index (Balthazar score)

Management

1. IV fluid resuscitation - aggressive early hydration (Lactated Ringer preferred over normal saline in some studies)
2. Pain control - IV opioids (morphine/hydromorphone)
3. NPO initially - restart oral feeding early (within 24-48h if tolerated); enteral nutrition via NG/NJ tube preferred over TPN in severe disease
4. Antiemetics for nausea
5. Monitoring for organ failure

• Gallstone pancreatitis: early ERCP if cholangitis or persistent biliary obstruction; cholecystectomy during same admission (mild disease) or after recovery
• ERCP pancreatitis prevention: rectal indomethacin, prophylactic pancreatic stent in high-risk patients
• Infected pancreatic necrosis: IV antibiotics (imipenem or meropenem) ± image-guided drainage or surgical necrosectomy
• Pseudocyst: most resolve spontaneously; endoscopic cystgastrostomy/cystduodenostomy if symptomatic
• Hypertriglyceridemia: insulin infusion, plasmapheresis in severe cases

• Routine antibiotics (no benefit in sterile necrosis)
• Nasogastric decompression routinely
• Early CT (first 24-48h rarely changes management)

CHRONIC PANCREATITIS

Definition

Causes

• Alcohol - most common (especially middle-aged men)
• Idiopathic (up to 40%) - many have CFTR, PRSS1, SPINK1 mutations
• Autoimmune pancreatitis (IgG4-related) - responds to steroids/anti-B cell therapy
• Duct obstruction, hyperparathyroidism, cystic fibrosis

Pathology (Morphology)

• Grossly: hard gland, dilated ducts, calcific concretions
• Microscopically:
  • Parenchymal fibrosis
  • Reduced/absent acini
  • Dilated ducts with ductal concretions
  • Relative sparing of islets early → eventual islet loss
  • Ductal epithelium: atrophy, hyperplasia, or squamous metaplasia
• Autoimmune type: lymphocyte + IgG4+ plasma cell infiltration, "swirling" fibrosis, venulitis

Clinical Features

• Recurrent epigastric/back pain - most common symptom
• Repeated bouts of jaundice
• Steatorrhea (exocrine insufficiency) - foul, greasy stools
• Diabetes mellitus (endocrine insufficiency - late)
• Weight loss, malabsorption
• May be silent until pancreatic insufficiency develops
• Increased risk of pancreatic adenocarcinoma

Diagnosis

• Plain X-ray/CT: pancreatic calcifications (pathognomonic)
• MRCP or ERCP: "chain of lakes" ductal appearance
• EUS: excellent for early/subtle changes
• Labs: lipase/amylase may be normal (burned-out gland)
• Fecal elastase: low in exocrine insufficiency
• Secretin stimulation test: most sensitive for exocrine function

Management

• Pain: analgesics, pancreatic enzyme supplements (reduce secretion), celiac plexus block, surgery
• Exocrine insufficiency: pancreatic enzyme replacement therapy (PERT) with meals
• Endocrine insufficiency: insulin for diabetes
• Alcohol cessation - mandatory
• Autoimmune pancreatitis: corticosteroids (dramatic response)
• Surgery/Endoscopy: duct decompression (Puestow procedure), partial resection for refractory pain or obstruction

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