9.4 Biliary Tract Diseases & Pancreatitis

9.4 Biliary Tract Diseases & Pancreatitis

High-Yield Overview: Disorders of the biliary tree and pancreas represent frequent emergency department presentations. Clinical mastery requires distinguishing localized gallbladder disease (cholecystitis) from common bile duct obstruction (choledocholithiasis, cholangitis) and applying evidence-based diagnostic criteria and fluid resuscitation strategies for acute and chronic pancreatitis.

---

Spectrum of Biliary Tract Disease

Biliary tract pathology depends on the exact anatomical site of ductal obstruction and the presence of bacterial infection.

---

Diagnostic Algorithms for Biliary Disease

                 Suspected Biliary Tract Symptoms
                                |
               Initial RUQ Abdominal Ultrasound
                                |
       +------------------------+------------------------+
       |                                                 |
Gallstones + Wall Thickening (>4mm)              CBD Dilation (>6mm) OR
OR Pericholecystic Fluid                        Jaundice / Elevated Bilirubin
       |                                                 |
Acute Cholecystitis                             Assess Cholangitis Risk
       |                                                 |
  +----+----+                                    +-------+-------+
  |         |                                    |               |
Equivocal Confirmed                        Charcot Triad    No Infection
  |         |                              (Emergency ERCP)      |
HIDA Scan Laparoscopic                                    MRCP or EUS
(No Fill) Cholecystectomy                                 before ERCP

1. First-Line Modality: Right Upper Quadrant Abdominal Ultrasound is the initial diagnostic test for all suspected biliary pathology (>95% sensitivity for gallstones).
2. Equivocal Cholecystitis: Perform HIDA Scan (Cholescintigraphy). Failure of radiotracer to visualize the gallbladder due to cystic duct obstruction confirms acute cholecystitis.
3. Choledocholithiasis Stratification:
   • High Risk (Jaundice, visible stone on US, ascending cholangitis): Proceed directly to ERCP.
   • Intermediate Risk (CBD dilation >6 mm, elevated Alk Phos/transaminases): Perform MRCP or Endoscopic Ultrasound (EUS) to confirm stone presence prior to invasive therapeutic ERCP.

---

Acute Pancreatitis: Etiology, Diagnosis & Staging

Etiologies

1. Gallstones (40%): Most common cause overall.
2. Alcohol (30%): Second most common cause.
3. Hypertriglyceridemia (1-4%): Serum triglycerides >1000 mg/dL.
4. Post-ERCP: Occurs in 3-5% of procedures.
5. Medications: Azathioprine, 6-MP, valproic acid, thiazides, furosemide, didanosine.
6. Hypercalcemia, Trauma, Autoimmune, Scorpion Stings.

Diagnostic Criteria (Requires >=2 of 3 Criteria)

1. Acute onset of severe, persistent epigastric pain radiating to the back.
2. Serum Lipase or Amylase >3 times the upper limit of normal (Lipase is more specific and remains elevated for 8-14 days).
3. Characteristic cross-sectional abdominal imaging findings (contrast-enhanced CT, MRI, or ultrasound).

Clinical Note: Abdominal CT is NOT required on admission if criteria 1 and 2 are satisfied. Contrast-Enhanced CT (CECT) should be performed at 72 hours after presentation to accurately evaluate for pancreatic necrosis if the patient fails to improve.

Severity Assessment & Clinical Signs

• BISAP Score (Evaluated within first 24h): BUN >25 mg/dL, Impaired mental status (GCS <15), SIRS criteria met, Age >60, Pleural effusion present. Score >=3 indicates high mortality risk.
• Physical Signs of Severe Hemorrhagic Pancreatitis:
  • Grey Turner Sign: Flank ecchymosis.
  • Cullen Sign: Periumbilical ecchymosis.

Acute Medical Management Principles

• Fluid Resuscitation: Aggressive IV isotonic crystalloids (Lactated Ringer's at 200–500 mL/hr or 5–10 mL/kg/hr) to maintain urine output >0.5 mL/kg/hr.
• Pain Management: IV opioids (hydromorphone, fentanyl).
• Nutrition: Early oral/enteral feeding within 24–48 hours is preferred over TPN to preserve the gut mucosal barrier and prevent bacterial translocation.
• Antibiotics: Prophylactic antibiotics are not recommended for uninfected pancreatitis or sterile necrosis.

---

Complications of Acute & Chronic Pancreatitis

Local Complications of Acute Pancreatitis

• Pancreatic Pseudocyst: Fluid collection rich in pancreatic enzymes encapsulated by fibrous/granulation tissue (lacks an epithelial lining). Forms >4 weeks after acute pancreatitis.
  • Management: Asymptomatic <6 cm -> Observation; Symptomatic, infected, or >6 cm persisting >6 weeks -> Endoscopic transmural drainage (cystogastrostomy).
• Infected Pancreatic Necrosis: Suspected when a patient develops fever, leukocytosis, and clinical deterioration 2 to 3 weeks into the hospital course. CT shows gas bubbles within necrotic tissue. Treatment includes broad-spectrum IV antibiotics (imipenem, meropenem) and delayed endoscopic/surgical necrosectomy (>4 weeks post-onset).

Chronic Pancreatitis

Progressive, irreversible pancreatic parenchyma destruction and fibrosis, primarily caused by chronic alcohol abuse (>70%) or cystic fibrosis (CFTR mutations).

• Classic Diagnostic Triad:
  1. Pancreatic Calcifications: Visible on plain abdominal X-ray or CT.
  2. Steatorrhea: Fat malabsorption leading to bulky, foul-smelling stools (fecal elastase-1 <200 mcg/g or 24-hour fecal fat >7 g/day).
  3. Diabetes Mellitus: Pancreatogenic (Type 3c) diabetes from beta-cell destruction.
• Management: Alcohol and tobacco cessation, Pancreatic Enzyme Replacement Therapy (PERT) taken WITH meals, low-fat diet, and insulin for glycemic control.