A 38-year-old woman presents with acute-onset severe epigastric pain and vomiting for 8 hours. She has no prior medical history and denies alcohol use. On examination, she is afebrile, BP 128/82 mmHg, HR 98/min. Serum amylase is 950 U/L, lipase 1800 U/L, and bilirubin 2.8 mg/dL (direct 1.9 mg/dL). Abdominal ultrasound shows a 1.2 cm gallstone in the gallbladder, a dilated common bile duct (8 mm), and no pancreatic changes. What is the most likely etiology and the most appropriate immediate management?

Explanation

## Biliary Pancreatitis: Diagnosis and Acute Management ### Clinical Recognition The constellation of findings points to **acute biliary pancreatitis with choledocholithiasis**: - Gallstone on ultrasound - Dilated CBD (>7 mm is abnormal) - Elevated bilirubin (suggests obstruction) - Elevated amylase and lipase - No history of alcohol use (excludes alcoholic pancreatitis) - Afebrile and hemodynamically stable (no signs of infected necrosis) ### Pathophysiology Gallstones cause pancreatitis by: 1. Transient obstruction of the ampulla of Vater 2. Increased intraductal pressure 3. Pancreatic duct rupture and autodigestion 4. Reflux of bile into pancreatic ducts **Key Point:** In biliary pancreatitis with **persistent** CBD obstruction (evidenced by dilated duct and hyperbilirubinemia), ERCP is indicated to relieve obstruction and prevent cholangitis. ### ERCP Timing in Biliary Pancreatitis | Scenario | Timing | Rationale | |---|---|---| | **Biliary pancreatitis + cholangitis** | Urgent (within 24 hrs, ideally <12 hrs) | Sepsis risk; high mortality if untreated | | **Biliary pancreatitis + CBD obstruction (no cholangitis)** | Within 24–48 hrs | Prevents cholangitis; improves outcomes | | **Biliary pancreatitis + patent CBD** | Conservative management | ERCP not indicated; risk outweighs benefit | | **Predicted severe pancreatitis + biliary cause** | Within 24 hrs | Reduces organ failure | **High-Yield:** ERCP within 24 hours in biliary pancreatitis with CBD obstruction reduces morbidity and mortality compared to delayed or no intervention. ### Why NOT the Other Options? **Alcoholic pancreatitis** (Option A): - Patient explicitly denies alcohol use - Alcoholic pancreatitis typically presents with chronic history, not acute onset in a non-drinker - High-dose antibiotics are NOT indicated in uncomplicated acute pancreatitis (prophylactic antibiotics only in necrosis or sepsis) **Idiopathic pancreatitis with microlithiasis** (Option C): - MRCP is useful for suspected microlithiasis, but this patient has **overt gallstone disease** on ultrasound - Microlithiasis is a diagnosis of exclusion; this is not the case here - MRCP would delay definitive treatment (ERCP) **Hypertriglyceridemic pancreatitis** (Option D): - Triglyceride-induced pancreatitis typically occurs with levels >1000–1500 mg/dL - Gallstone disease is already identified; this is the primary etiology - Lipid-lowering therapy alone is insufficient if CBD obstruction persists ### Management Algorithm ```mermaid flowchart TD A[Acute pancreatitis + gallstone on US]:::outcome --> B{CBD dilated or bilirubin elevated?}:::decision B -->|Yes| C[ERCP within 24-48 hrs]:::action B -->|No| D[Conservative management]:::action C --> E[Sphincterotomy + stone extraction]:::action E --> F[Resolve obstruction]:::outcome D --> G[Monitor for recurrence]:::action G --> H[Elective cholecystectomy after recovery]:::action ``` **Clinical Pearl:** All patients with biliary pancreatitis require cholecystectomy (or ERCP + sphincterotomy if unfit for surgery) to prevent recurrence. Recurrence rate without intervention is ~30% within 1 month. **Mnemonic: ERCP-BILE** — ERCP indicated in biliary obstruction, Urgent if cholangitis, Relieves ductal pressure, Prevents complications, Bilirubin elevated, Ileostomy (pancreatic rest), Lipase/amylase elevated, Early intervention improves outcomes. [cite:Harrison 21e Ch 330; Tenner AC et al. American College of Gastroenterology Guideline 2013]