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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
Key points
- Choledocholithiasis = common bile duct stone; cholangitis = infected obstructed biliary system
- Charcot triad: fever, RUQ pain, jaundice; Reynolds pentad adds hypotension and altered mental status
- High-risk stones: CBD stone on imaging, cholangitis, or bilirubin >4 plus duct dilation — proceed to ERCP
- Intermediate risk: MRCP or EUS before ERCP
- Acute cholangitis requires IV antibiotics plus biliary decompression, usually ERCP within 48 h or sooner if severe
Overview
Choledocholithiasis causes cholestatic liver enzyme elevation, jaundice, and duct dilation. Bacterial infection behind obstruction causes acute cholangitis and can rapidly progress to sepsis. ERCP is therapeutic but carries pancreatitis risk, so noninvasive imaging is preferred for intermediate probability.
Epidemiology
CBD stones are more common with older age, gallstone pancreatitis, jaundice, CBD dilation, and cholestatic labs. Cholangitis is life-threatening without drainage. Common organisms include E coli, Klebsiella, Enterococcus, and anaerobes.
Clinical Features
Symptoms
RUQ or epigastric pain, often after fatty meals
Pain radiates to right shoulder/scapula
Nausea and vomiting
Jaundice, dark urine, pale stools with duct obstruction
Fever, chills, hypotension, confusion, or persistent pain
Signs
RUQ tenderness
Positive Murphy sign in cholecystitis
Scleral icterus with CBD obstruction
Reynolds pentad: fever, jaundice, RUQ pain, hypotension, altered mental status
Investigations
First-line
RUQ ultrasoundFirst-line for gallstones, wall thickening, CBD dilation
CBC, CMP, lipaseLeukocytosis, cholestatic labs, pancreatitis assessment
Blood cultures and lactateIf cholangitis or sepsis suspected
Second-line
HIDA scanMost sensitive for cholecystitis when ultrasound equivocal
MRCP or EUSIntermediate probability CBD stones
CT abdomenComplications or alternative diagnosis
Specialist
ERCPTherapeutic for cholangitis or high-risk choledocholithiasis
Intraoperative cholangiographyCBD stone evaluation during cholecystectomy
1
Biliary colic/cholecystitis
- Elective cholecystectomy for recurrent biliary colic
- Acute cholecystitis: NPO, IV fluids, analgesia, antibiotics
- Early laparoscopic cholecystectomy during index admission
2
Choledocholithiasis
- High-risk CBD stone: ERCP
- Intermediate risk: MRCP/EUS before ERCP
- Cholecystectomy after duct clearance when appropriate
3
Cholangitis
- Immediate broad-spectrum IV antibiotics and fluids
- Urgent ERCP for drainage, within 48 h and sooner if severe
- ICU care for shock or organ failure
Complications
- Gallstone pancreatitis: Ampullary obstruction.
- Ascending cholangitis: Infected obstructed duct.
- Gangrenous/perforated cholecystitis: Peritonitis and sepsis.
- Gallstone ileus: Pneumobilia, SBO, ectopic stone.
USMLE Step 2 CK Exam Tips
- 1Biliary colic has no fever or leukocytosis
- 2RUQ ultrasound is first test
- 3HIDA follows equivocal ultrasound in suspected cholecystitis
- 4Charcot triad = fever + RUQ pain + jaundice; treat with antibiotics + ERCP
- 5CBD stone seen on imaging = ERCP
- 6Intermediate risk choledocholithiasis gets MRCP/EUS
- 7Gallstone ileus: pneumobilia + SBO + ectopic gallstone
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