Cholangitis and Choledocholithiasis

• Mechanical obstruction and increased intraductal pressure: Stone impaction or stricture within the CBD creates a physical barrier to bile flow. This leads to rapid elevation of intraductal pressure (normally 10-15 cm H₂O) to 40+ cm H₂O within minutes. The pressure gradient disrupts the integrity of tight junctions between cholangiocytes and the capillary endothelium, allowing bacterial translocation from the portal blood and duodenal reflux of enteric organisms into the biliary tree (ascending cholangitis). In choledocholithiasis without infection, the mechanical obstruction causes conjugated hyperbilirubinemia as bile backs up into hepatic sinusoids, with cholestasis-induced lipid peroxidation potentially triggering hepatocellular necrosis if prolonged. The degree of pressure elevation directly correlates with risk of bacterial translocation—this is the fundamental mechanism explaining why partial obstruction may be more dangerous than complete obstruction (complete obstruction prevents reflux, while partial allows bidirectional flow).

• Bacterial pathogenesis and inflammatory cascade: Once bacteria access the biliary system (E. coli in 40-50%, Klebsiella in 15-25%, enterococci, anaerobes, and Bacteroides in mixed infections), they proliferate rapidly in the stagnant, nutrient-rich biliary environment. Bacterial lipopolysaccharides and lipoteichoic acids activate toll-like receptors on cholangiocytes and hepatic macrophages (Kupffer cells), triggering robust innate immune activation with massive release of TNF-α, IL-6, IL-8, and other inflammatory mediators. This inflammatory surge increases vascular permeability, causes systemic vasodilation and myocardial depression (septic shock physiology), and promotes polymorphonuclear neutrophil infiltration into bile ducts. The combination of increased intraductal pressure, bacterial endotoxemia, and overwhelming inflammation can lead to frank bacteremia in 50-90% of cases, with the risk of progression to septic shock (mortality 5-10% if untreated vs. <1% with prompt decompression). Additionally, bile salt-induced injury to the bile duct epithelium impairs mucosal barrier function, further facilitating translocation.

• Stone formation mechanisms and risk stratification: Choledocholithiasis develops either through primary stone formation (less common, occurring de novo in the CBD, more prevalent in East Asian populations with intrahepatic cholangitis) or secondary stone formation (90% of cases in Western populations, where stones originate in the gallbladder and migrate through the cystic duct). Risk factors for migration include stone size <20 mm and gallbladder contractility patterns. In primary stone disease, bile stasis from strictures or parasitic infection (Clonorchis sinensis, Opisthorchis viverrini—endemic in Southeast Asia) promotes stone precipitation around bacterial biofilms. The cholesterol saturation index increases with cholestasis, and lecithin hydrolysis by bacterial phospholipases accelerates pigment stone formation. Black pigment stones (in hemolytic disease) are more likely to fragment and migrate to cause obstruction compared to cholesterol stones. Brown pigment stones in Asian populations are associated with chronic cholangitis and bacterial colonization.

• Anatomical factors promoting stasis and stone entrapment: Sphincter of Oddi dysfunction (elevated basal pressure or paradoxical response to cholecystokinin), ampullary stenosis from fibrosis or prior papillotomy, and fixed strictures from PSC or malignancy create obstruction points where stones become impacted. The CBD narrows at three natural points—the hepatic convergence, the intrapancreatic segment, and the ampulla—making the distal CBD most common site for stone impaction. Bile duct diameter >15 mm increases risk of stone retention; stones dilate the duct over time, creating the "vicious cycle" where the enlarged duct cannot clear retained stones and the resulting stasis promotes further stone formation.

• Gallstone disease (secondary choledocholithiasis): The most common source of CBD stones in Western populations. Prior cholecystectomy does NOT eliminate risk—stones can still migrate from a remnant gallbladder or form de novo in the CBD post-operatively. Risk factors for gallstone formation (obesity, female sex, forty-plus age, fertile history, family history, rapid weight loss, cirrhosis with portal hypertension) predispose to both gallstone disease and subsequent choledocholithiasis. Approximately 8-20% of patients with gallstones have concurrent choledocholithiasis; this percentage increases with age and in patients with dilated bile ducts on imaging.

• Primary sclerosing cholangitis (PSC): A crucial predisposing condition for primary choledocholithiasis, where chronic inflammation causes strictures, intrahepatic stone formation, and bacterial colonization. PSC patients have 20-30% risk of cholangitis episodes. The stricturing pattern alternates with dilations ("string of pearls"), creating stagnation zones promoting stone nucleation. Malignant transformation to cholangiocarcinoma occurs in 10-20% of PSC patients, and strictures may represent early malignancy rather than benign PSC—a critical diagnostic distinction.

• Parasitic infection and endemic disease: In East and Southeast Asia, parasitic biliary infections (particularly Clonorchis sinensis from raw freshwater fish, also Opisthorchis viverrini) cause chronic cholangitis, stricturing, intrahepatic stone formation, and dramatically increase cholangiocarcinoma risk. These parasites cause mechanical irritation, chronic inflammation, and bile stasis. Brown pigment stones form around parasitic debris and bacterial biofilms. This is the primary etiology of intrahepatic stone disease in endemic regions.

• Biliary strictures and anatomical abnormalities: Post-sphincterotomy strictures (iatrogenic, from prior ERCP), anastomotic strictures following choledochojejunostomy, congenital choledochal cysts, intrahepatic biliary dilatation from PSC or Caroli disease, and ampullary stenosis all predispose to stasis and stone formation. Cystic dilatation of the biliary tree (Caroli syndrome) is particularly high-risk for recurrent cholangitis and requires careful long-term monitoring.

• Malignant obstruction: Pancreatic cancer (head of pancreas), cholangiocarcinoma, and ampullary adenocarcinoma can cause acute cholangitis through mechanical obstruction with subsequent bacterial overgrowth and ascending infection. Cholangitis in malignancy may be the presenting feature; persistent or recurrent cholangitis despite stone extraction should raise suspicion for underlying malignancy.

• Bile duct dilatation: CBD diameter >10 mm (>12 mm in the elderly) increases risk of stone formation and retention. Pregnancy can cause physiologic dilatation with altered bile composition (increased progesterone effects on sphincter pressure and bile viscosity), increasing risk of both gallstones and CBD stones.

• Sphincter of Oddi dysfunction: Elevated basal pressure, paradoxical response to cholecystokinin, or tachykinetic (rapid contraction) patterns impair bile drainage and promote stasis, though this diagnosis remains controversial and should be made cautiously.

• Charcot's triad of acute cholangitis: The classic presentation comprises fever (90% of cases, often with rigors and septic pattern), right upper quadrant pain (usually colicky, from increased ductal pressure and stretching of the visceral peritoneum), and jaundice (from conjugated hyperbilirubinemia due to obstruction). The fever is typically high-grade (>39°C) and may be intermittent or spiking in pattern. The pain is usually steady rather than the colicky pattern of simple biliary colic because it reflects sustained ductal pressure elevation rather than transient muscular contraction. The jaundice develops over hours to days as bilirubin backs up into bloodstream; rapid onset within hours suggests complete obstruction while gradual onset suggests partial obstruction. The triad is only present in approximately 50-70% of cases, so absence does not exclude diagnosis—monoarthritis of the fever alone can be the presenting feature in elderly or immunocompromised patients.

• Reynolds' pentad (Charcot's triad plus hypotension and altered mental status): This indicates progression to septic shock and represents a medical emergency. Hypotension occurs from distributive shock secondary to massive release of inflammatory mediators causing vasodilation and myocardial depression. Altered mental status (confusion, delirium, coma) reflects hepatic encephalopathy from severe hepatic dysfunction, systemic inflammatory response syndrome (SIRS) affecting cerebral perfusion, or direct central nervous system effects of endotoxemia. Mortality rises dramatically when septic shock develops (30-50% without urgent intervention, <5% with prompt decompression).

• Choledocholithiasis without cholangitis: Patients may present with biliary colic (sharp RUQ pain lasting 30 minutes to several hours, often postprandial) or obstructive jaundice (painless or minimally symptomatic jaundice with dark urine and pale stools) without fever. The asymptomatic form is discovered incidentally on ultrasound performed for other reasons; approximately 80% of patients with incidentally discovered CBD stones never develop cholangitis if untreated. Painless jaundice is the classic presentation of malignant obstruction but can occur with stone obstruction, particularly in elderly patients where symptoms may be blunted.

• Atypical presentations: Elderly patients, diabetics, and immunocompromised patients may present with septic shock or altered mental status as the sole manifestation, with absent or minimal jaundice and pain—a particularly dangerous presentation because the diagnosis is easily missed. Pregnant patients with cholangitis present with similar symptoms but require special diagnostic and therapeutic considerations. HIV-infected patients may develop sclerosing cholangitis from CMV, Cryptosporidium, or microsporidium, causing severe immunosuppression (CD4 <100).

• Physical examination findings: Fever is present in the majority (90%). Murphy's sign (inspiratory arrest during palpation of the RUQ due to pain from the inflamed gallbladder fundus touching the examiner's hand) is present in cholecystitis but not specific for cholangitis. Courvoisier's sign (palpable, non-tender gallbladder in the setting of jaundice) suggests malignant obstruction rather than stone disease (in malignancy, the gallbladder is often dilated because stones have not previously caused inflammation and fibrosis). Icterus is visible in sclera and skin when conjugated bilirubin exceeds 3 mg/dL. Right upper quadrant tenderness, hepatomegaly, and occasionally abdominal distension from peritonitis (if perforation occurs) may be noted. Signs of sepsis (tachycardia, tachypnea, hypotension) indicate severe disease requiring urgent intervention.

• Clinical diagnosis criterion: Acute cholangitis should be suspected in any patient presenting with fever and jaundice, particularly if RUQ pain is present. The Tokyo Guidelines 2018 (most widely used criteria) define cholangitis as fever AND (biliary obstruction AND/OR imaging findings of cholangitis), or fever AND sepsis with no other source AND imaging suggesting biliary obstruction. This framework improves early recognition and guides urgency of intervention. Diagnosis of choledocholithiasis may be suspected from clinical presentation but requires imaging confirmation.

• Laboratory studies reflecting biliary obstruction and inflammation:
• Alkaline phosphatase and bilirubin elevation: ALP typically rises to 4-10 times the upper limit of normal (normal <104 U/L), reflecting induction of ALP synthesis by obstructed hepatocytes. Conjugated hyperbilirubinemia typically exceeds 80% of total bilirubin. In obstructive jaundice from stones, the bilirubin level may reach 5-10 mg/dL or higher depending on duration and completeness of obstruction. The degree of elevation does not correlate with severity of infection.
• Transaminases (AST/ALT): Often minimally elevated (<4 times normal) in pure obstruction; more marked elevation (>10 times normal) suggests hepatocellular inflammation (viral hepatitis, alcoholic hepatitis, ischemic hepatitis from sepsis). ALT is more specific for hepatocellular injury than AST.
• Leukocytosis: White blood cell count typically elevated to 12,000-20,000/μL with left shift (increased immature forms) reflecting acute bacterial infection. Absence of leukocytosis in a septic patient portends worse prognosis.
• Blood cultures: Positive in 50-90% of cholangitis cases; identify organism and guide antibiotic therapy. Multiple sets should be obtained before antibiotic initiation when possible, though empiric antibiotics should never be delayed if septic cholangitis is suspected.
• Prothrombin time (PT)/INR elevation: May be present due to vitamin K malabsorption (fat-soluble vitamin) from impaired bile salt delivery to the intestine; corrects with parenteral vitamin K administration.

• Abdominal ultrasound: The initial imaging modality of choice for suspected biliary pathology due to availability, safety, and excellent sensitivity (95%) for gallstones. Findings include: dilated intrahepatic bile ducts (>5 mm diameter), dilated CBD (>6 mm, or >8 mm if post-cholecystectomy), echogenic stones with acoustic shadowing (though absent in 15% of stones), and direct visualization of stone in the CBD (high specificity but low sensitivity—found in only 5-10% of cases). Limitations include operator dependence and poor sensitivity for detecting distal CBD stones obscured by bowel gas.

• Magnetic resonance cholangiopancreatography (MRCP): The gold standard noninvasive imaging modality for CBD stone detection with sensitivity 90-95% and specificity >95%. MRCP provides excellent visualization of the entire biliary tree, pancreatic duct, and can identify strictures, malignancy, or anatomical variants. T2-weighted sequences excellently depict stone filling defects within the T-shaped biliary ducts. Unlike ERCP, MRCP is diagnostic only and carries no procedural risk, making it the preferred imaging study when diagnosis of choledocholithiasis is uncertain. Limitations include cost and reduced availability; contraindications are cardiac pacemakers (though newer MRI-conditional devices exist) and severe renal insufficiency (gadolinium contrast).

• CT of the abdomen: Sensitivity 50-75% for CBD stones (lower than MRCP) but helpful for detecting complications (cholecystitis, pancreatitis, perforation) and excluding other diagnoses (acute coronary syndrome, aortic pathology). Pneumobilia with emphysematous cholecystitis suggests infected obstructed bile ducts with gas-forming organisms—a surgical emergency.

• ERCP (Endoscopic Retrograde Cholangiopancreatography): Both diagnostic and therapeutic; allows direct visualization of the ampulla, identification of stone location, and immediate extraction via sphincterotomy and stone retrieval. ERCP has sensitivity >95% for CBD stones but carries procedural risks (pancreatitis in 3-7%, perforation, bleeding). ERCP should be performed urgently (within 24-48 hours) in confirmed or highly suspected cholangitis to achieve biliary decompression. Post-sphincterotomy strictures may develop in 5-15% of cases long-term.

• Diagnostic score for cholangitis (Tokyo Guidelines 2018): Assigns points for fever (1 point), RUQ pain (1), jaundice (1), elevated ALT/ALP/bilirubin (1), dilated CBD on ultras

Immediate stabilisation (all suspected cholangitis)

• Resuscitation and source-control mindset: NPO, isotonic crystalloid for sepsis-induced hypoperfusion, blood cultures ×2 before antibiotics, and vasopressors (norepinephrine first-line) if mean arterial pressure remains low after fluids — the Surviving Sepsis Campaign framework. Correct coagulopathy from vitamin K malabsorption with parenteral vitamin K (± plasma or 4-factor PCC if bleeding or urgent sphincterotomy).

First-line antimicrobial therapy

• Beta-lactam/beta-lactamase inhibitor: piperacillin-tazobactam is the prototypical empiric agent, covering E. coli, Klebsiella, enterococci and anaerobes. A third-generation cephalosporin (ceftriaxone) plus metronidazole is an accepted alternative in community-acquired, non-severe disease per Tokyo Guidelines 2018 and IDSA/Surgical Infection Society intra-abdominal infection guidance.
• Escalation: a carbapenem (meropenem) for Tokyo Grade III (organ dysfunction), healthcare-associated infection, indwelling stents, or known ESBL colonisation. Add vancomycin when enterococcal or MRSA risk exists; if vancomycin is used, dose to a 24-hour AUC targeting AUC/MIC 400–600 (2020 IDSA/ASHP consensus), not a trough.

Definitive management — biliary decompression

• ERCP with sphincterotomy and stone extraction is the definitive intervention. Tokyo Guidelines 2018: urgent drainage (within ~24 hours) for severe/Grade III disease or any patient failing initial medical therapy; early drainage for moderate disease.
• If ERCP fails or anatomy precludes it (Roux-en-Y, duodenal obstruction): percutaneous transhepatic biliary drainage, EUS-guided drainage at experienced centres, or open/laparoscopic CBD exploration.
• Cholecystectomy: after clinical resolution, laparoscopic cholecystectomy on the same admission for gallstone-related disease (ASGE and SAGES), since interval delay carries high recurrence.

Emergencies

• Septic shock and multiorgan failure: endotoxin-driven vasodilation and myocardial depression from bacteria forced across the cholangiocyte barrier by high intraductal pressure. Signalled by hypotension, altered mentation (Reynolds pentad), rising lactate, oliguria. Demands resuscitation plus emergent drainage — antibiotics alone will not work against an obstructed, pressurised duct.
• Pyogenic liver abscess: retrograde spread of infected bile into hepatic parenchyma. Suspect when fever and leukocytosis persist after apparently successful drainage; CT shows a rim-enhancing hepatic collection requiring percutaneous drainage.
• Pylephlebitis (septic portal vein thrombophlebitis): suppurative thrombosis of the portal system with persistent bacteremia; portal vein thrombus with surrounding inflammation on contrast CT.
• Bile duct perforation with bile peritonitis: pressure necrosis of an inflamed duct; diffuse peritoneal signs and free fluid or pneumobilia/free air on imaging.

Disease-related, non-immediate

• Gallstone pancreatitis: a stone impacted at the ampulla obstructs the pancreatic duct; epigastric pain radiating to the back with lipase markedly elevated.
• Secondary biliary cirrhosis: chronic or recurrent obstruction drives periportal fibrosis; progressive cholestatic labs, hepatosplenomegaly, portal hypertension.
• Cholangiocarcinoma: chronic biliary inflammation from hepatolithiasis, PSC, or liver flukes; painless jaundice with a dominant stricture and weight loss.
• Acute kidney injury: combined septic and cholemic (bile cast) nephropathy.

Treatment-related

• Post-ERCP pancreatitis: the most common ERCP complication (roughly 3–7%); sphincter trauma and ductal hydrostatic injury. Persistent post-procedure pain with rising lipase — not the transient asymptomatic hyperamylasemia that is common after ERCP.
• Post-sphincterotomy hemorrhage: incision through a retroduodenal artery branch; melena or hematemesis, falling hemoglobin.
• Retroperitoneal duodenal or ductal perforation: retroperitoneal air on CT — a surgical emergency.
• Stent occlusion or migration and late sphincterotomy stenosis: biofilm-driven; presents as recurrent cholangitis weeks to years later.

• Charcot triad (fever, RUQ pain, jaundice) suggests cholangitis; Reynolds pentad adds hypotension and altered mental status and means septic cholangitis until proven otherwise. Neither is required for diagnosis — Tokyo Guidelines 2018 combine systemic inflammation, cholestasis, and imaging.
• The single best next step in a septic, jaundiced patient is fluids plus empiric IV antibiotics followed by urgent ERCP for decompression. Do not choose MRCP, EUS, or observation for a hypotensive patient — those are for diagnostic uncertainty, not for source control.
• Antibiotics do not substitute for drainage. An obstructed duct is a closed-space infection; the exam answer is always decompression.
• E. coli is the most commonly isolated organism, followed by Klebsiella and enterococci; empiric coverage must include enteric gram-negatives and anaerobes.
• The association examiners love: PSC (with ulcerative colitis) → recurrent cholangitis, dominant strictures, beads-on-a-string cholangiogram, and a substantial lifetime cholangiocarcinoma risk. In Southeast Asia, Clonorchis sinensis plays the analogous role.
• Do the cholecystectomy on the same admission after cholangitis resolves and the duct is cleared (ASGE/SAGES);