Pancreatitis: Acute

(Am J Gastroenterol 2006;101:2379-2400 & 1997;92:377-86. N Engl J Med 2006;354:2142-50. J Hepatobil Pancreat Surg 2006;13:56-60)

DEFINITION:

Acute pancreatitis: inflammatory condition of the pancreas that may extend to local and distant extrapancreatic tissues
- Interstitial pancreatitis: mild acute pancreatitis, based on radiographic appearance; Implies preservation of pancreatic blood supply
- Necrotizing (Severe) pancreatitis: implies presence of organ failure, local complications or pancreatic necrosis
Acute recurrent pancreatitis: acute pancreatitis occurring two or more occasions (evidenced by elevation of the serum pancreatic enzymes)

EPIDEMIOLOGY:

Over 200,000 new cases a year (80% are interstitial or edematous variety and 20% are necrotizing or severe variety)
See also Etiologies below

ETIOLOGIES:

Common:
- Gallstones (40% of cases, typically women): usually small (<5 mm) stones are culprit; Mortality 12% during first attack
- Alcohol (30% of cases, typically men, lower socioeconomic): usually chronic with acute flares
- Idiopathic (20-25% of cases), however, in 2/3 of these patients
  - Microlithiasis (“Biliary sludge”) is identified 70% with repeat U/S
Rare:
- Obstructive: ampullary or pancreatic tumors, pancreas divisum (controversial)
- Metabolic: TG >750 for type I & V familial hypertriglyceridemia; TG usually ˜ 4500; Hypercalcemia/Hyperparathyroidism
- Meds (5% of case): furosemide, thiazides, azathioprine/6-MP, valproic acid, estrogens, didanosine, sulfa, protease inhibitors, ACE-I
- Infection: Echovirus, Coxsackievirus, Mumps, Rubella, EBV, CMV, HIV, HAV, HBV, Ascaris, Mycoplasma, Salmonella, TB
- Ischemia from any cause
- Trauma: blunt abdominal trauma, Post ERCP; See also Endoscopy & Procedures- ERCP (Chapter 7.06)
- Pregnancy: most occur in 3rd trimester or postpartum; Coexisting stones in 90% of cases
- Scorpion sting (in Trinidad)
- Post-transplant: think secondary hyperparathyroidism, hyperlipidemia, viral infections, vasculitis, immunosuppressive (Treatment with steroids)
- In HIV/AIDS: think infection (CMV, fungal, MAI, Toxo, Pneumocystis), drugs (Didanosine, Bactrim), other (Kaposi’s, lymphoma)
DDX:
- Biliary disease, PUD, perforated viscus, small bowel obstruction, mesenteric ischemia, MI, AAA leak, distal aortic dissection

PATHOPHYSIOLOGY:

Premature activation of trypsin within pancreatic acinar cells » activation of digestive enzymes leading to pancreatic inflammation
Two forms defined by inflammatory changes in the pancreatic parenchyma are “interstitial” and “necrotizing”
- Interstitial (85%): edema and inflammation of the pancreatic parenchyma occur without death of pancreatic acini
- Necrotizing (15%): extensive parenchymal destruction, frequency with peripancreatic fat necrosis

CLINICAL MANIFESTATIONS/PHYSICAL EXAM:

Ranges from mild nonspecific epigastric pain to catastrophic acute medical illness
In general: epigastric abdominal tenderness/pain, radiating to the back, constant, little change with position; ± guarding
N/V & Fever is common
Other clinical signs:
- ↓ bowel sounds (adynamic ileus), ± palpable abdominal mass; ± jaundice if biliary obstruction
- Signs of retroperitoneal hemorrhage are uncommon: Cullen’s » periumbilical; Grey Turner’s » flank (“turn” patient to see flank)
- ± Hypotension or shock (tachycardia, tachypnea, hypotension) from cytokine release