Pancreatitis_diagnostic_criteria.txt

### 1. Diagnostic Criteria for Acute Pancreatitis  
Diagnosis requires **at least two of the following three categories**:

1. Clinical Symptoms (at least one):
   - Acute onset of persistent epigastric pain (often radiating to the back)
   - Abdominal tenderness (epigastric or diffuse)

2. Laboratory Evidence (at least one):
   - Serum amylase > 3× upper limit of normal (ULN)
   - Serum lipase > 3× ULN (lipase is more specific)

3. Imaging Evidence (at least one; CT/MRI preferred):
   - CT or MRI showing pancreatic edema, necrosis, or peripancreatic fluid
   - Ultrasound showing pancreatic swelling ± peripancreatic fluid

---

### 2. Typical Imaging Findings in Acute Pancreatitis
- Pancreatic enlargement
- Hypoechoic or hypoattenuating pancreas
- Peripancreatic fat stranding
- Pericholecystic fluid collection
- Gallstones, sludge, or calcified gallstones
- Dilated bile ducts
- Gallbladder distention
- Gallbladder wall edema or thickening
- Absence of normal pancreatic parenchyma
- Pancreatic ductal dilation

---

### 3. Cholecystitis vs. Biliary Pancreatitis
Primary Lesion Site:
- Cholecystitis: Gallbladder
- Biliary Pancreatitis: Pancreas

Imaging Features:
- Cholecystitis: Gallbladder wall thickening, pericholecystic fat stranding/fluid, gallstones or sludge
- Biliary Pancreatitis: Pancreatic enlargement, peripancreatic fat stranding or fluid, pancreatic duct dilation, stone in the very distal common bile duct, small gallstones within gallbladder

Common Bile Duct (CBD) Dilation:
- Cholecystitis: May occur due to secondary inflammation
- Biliary Pancreatitis: Often >6 mm, suggests obstructing stone

Pancreatic Involvement:
- Cholecystitis: Pancreas usually normal
- Biliary Pancreatitis: Pancreatic edema, possible necrosis or pseudocyst

Biochemical Clues:
- Cholecystitis: Elevated WBC, CRP; liver enzymes normal or mildly increased
- Biliary Pancreatitis: Elevated amylase/lipase; ALT/AST may be elevated

Clinical Presentation:
- Cholecystitis: RUQ pain, positive Murphy's sign, possible fever
- Biliary Pancreatitis: Epigastric pain radiating to back, nausea/vomiting, Murphy's sign usually negative

---

### 4. Clinical Tips
- Amylase/lipase ≥ 3× ULN is the diagnostic cutoff
- CRP ≥ 150 mg/L on day 3 predicts severe acute pancreatitis
- Hematocrit > 44% is a risk factor for pancreatic necrosis
- Urea > 20 mg/dL predicts higher mortality
- Procalcitonin is sensitive for pancreatic infection; low values are strong negative predictors
- In absence of gallstones or alcohol history, evaluate:
   - Serum triglycerides > 11.3 mmol/L (1000 mg/dL): suggests hypertriglyceridemia-induced AP
   - Serum calcium: hypercalcemia may be the cause