Cholangitis is one of those GI emergencies that loves to show up as a “looks sick + RUQ pain” vignette—and the trick is recognizing it fast enough to treat before the patient spirals into septic shock. Here’s a quick, shareable visual hack plus the must-know Step facts.
The 10-second idea: what cholangitis is
Acute cholangitis = infection of the biliary tree due to obstruction + bacterial ascent from the duodenum.
Think: “blocked bile duct → stagnant bile → bacteria climb up → sepsis.”
Visual hack / mnemonic: “3 + 2 = 5 Alarm Cholangitis”
Picture a bile duct as a hallway with 5 alarm lights.
Charcot Triad (3 alarms)
Fever + RUQ pain + jaundice
- Fever = infection
- RUQ pain = biliary obstruction/inflammation
- Jaundice = blocked bile flow
Add 2 more alarms → Reynolds Pentad
Charcot triad + hypotension + altered mental status
= suppurative cholangitis with sepsis (ICU vibes)
One-liner: Charcot = cholangitis; Reynolds = cholangitis with septic shock.
What causes it? (High-yield etiologies)
Most commonly: choledocholithiasis (CBD stone). Others show up on exams too:
- Gallstones (most common)
- Biliary strictures (post-op, PSC)
- Malignancy (cholangiocarcinoma, pancreatic head cancer)
- Instrumentation (post-ERCP)
Bug clue: organisms typically resemble gut flora:
- E. coli, Klebsiella, Enterococcus, anaerobes sometimes
Pathophysiology you should say out loud in your head
Obstruction increases intrabiliary pressure → bile stasis → bacteria ascend → inflammation + bacteremia → sepsis.
This explains why cholangitis is:
- more toxic-appearing than uncomplicated biliary colic
- often has systemic signs (fever, hypotension)
How it presents (vignette patterns)
Classic stem features:
- Fever/chills + RUQ pain + jaundice
- May mention dark urine and pale stools (cholestasis)
- Older patient with known gallstones, or history of biliary procedures
If the question says:
- “confused, hypotensive” → think Reynolds pentad → urgent management
Labs & imaging: what’s high-yield
Labs (cholestatic pattern)
| Test | Typical finding | Why it matters |
|---|---|---|
| Alkaline phosphatase (ALP) | High | cholestasis marker |
| Direct (conjugated) bilirubin | High | obstruction |
| AST/ALT | Mild–moderate ↑ | can rise early |
| WBC | ↑ | infection |
| Blood cultures | may be positive | sepsis workup |
Imaging
- RUQ ultrasound: great first test to look for CBD dilation and stones (even if stone isn’t visualized)
- ERCP: both diagnostic + therapeutic (decompression/stone extraction)
Cholangitis vs cholecystitis (common Step trap)
| Feature | Cholangitis | Acute cholecystitis |
|---|---|---|
| Main issue | Infected, obstructed bile duct | Inflamed gallbladder (often cystic duct obstruction) |
| Key clue | Jaundice + systemic toxicity | Murphy sign, less prominent jaundice |
| Dangerous progression | Sepsis (Reynolds pentad) | Perforation/empyema |
| Key intervention | Antibiotics + biliary drainage (ERCP) | Antibiotics + cholecystectomy (after stabilization) |
Exam shortcut:
- Jaundice + fever → cholangitis until proven otherwise.
Management: the USMLE algorithm (memorize this)
Step 1: Stabilize + sepsis bundle
- IV fluids
- Broad-spectrum IV antibiotics covering gram negatives + anaerobes
- Common choices: piperacillin-tazobactam, or ceftriaxone + metronidazole
- Blood cultures (don’t delay antibiotics in a crashing patient)
Step 2: Source control (the testable “next best step”)
- Urgent ERCP for biliary decompression (stone removal/stent)
- If ERCP not possible: percutaneous transhepatic biliary drainage
High-yield line: Antibiotics alone are not enough if the duct is obstructed—drain the system.
Rapid-fire pearls (easy points)
- Reynolds pentad = emergency: hypotension + AMS means septic cholangitis
- Cholestatic labs (ALP, direct bilirubin) point you to the bile ducts
- ERCP is therapeutic (unlike MRCP, which is diagnostic only)
- Ascending cholangitis often occurs with CBD obstruction, not just gallbladder disease
Mini memory picture you can reuse
“Bile duct is a backed-up sewer.”
When it’s blocked, bacteria rise → fever, bile can’t drain → jaundice, pressure hurts → RUQ pain. Add septic physiology → hypotension + confusion.