GastroenterologyTier 1Disease (DEADMAN)

Biliary obstruction

Description

Mechanical obstruction to bile flow -> conjugated (direct) hyperbilirubinaemia + cholestatic LFTs
Intrahepatic vs extrahepatic - the first branch point, answered by imaging (ducts dilated or not)

Syndromes

Painless obstructive jaundice -> malignancy until proven otherwise
Biliary colic - RUQ/epigastric pain, <6 h, no fever, normal inflammatory markers
Acute cholecystitis - pain >6 h, fever, Murphy sign; cystic duct obstruction, usually not jaundiced
Choledocholithiasis - jaundice +/- pain
Ascending cholangitis - Charcot triad (fever, RUQ pain, jaundice); Reynolds pentad adds hypotension + confusion
Gallstone pancreatitis
Mirizzi syndrome - stone in cystic duct/Hartmann pouch compressing CHD

Choledochal cysts

Congenital dilatation of the biliary tract; CBD most often (Todani type I)
Older children: classic triad - abdominal pain + jaundice + RUQ mass (full triad in <20%)
Infants: cholestatic jaundice (differentiate from biliary atresia - a surgical emergency by 60 days)
Complications: pancreatitis, cholangitis, stones, cirrhosis, cholangiocarcinoma
Often anomalous pancreaticobiliary junction -> reflux of pancreatic enzymes into the duct

Epidemiology

Gallstones in ~15% of Australian adults; only ~20% ever symptomatic
CBD stones in ~10-15% of patients with gallbladder stones
Pancreatic cancer: incidence rising, 5-yr survival ~12%
Choledochal cysts: F>M (3-4:1), much commoner in East Asian populations
Cholangiocarcinoma: rising incidence; PSC is the major Western risk factor

Aetiopathogenesis

Extrahepatic (ducts dilated)

Luminal - CBD stones (commonest), parasites (Clonorchis, Ascaris), haemobilia
Mural - cholangiocarcinoma, ampullary carcinoma, benign/post-ERCP/ischaemic stricture, PSC, IgG4 sclerosing cholangitis, choledochal cyst
Extrinsic - pancreatic head carcinoma, chronic pancreatitis, pseudocyst, portal lymphadenopathy, Mirizzi

Intrahepatic (ducts NOT dilated)

PBC (AMA+), PSC, drug-induced cholestasis, sepsis, TPN
Infiltration - lymphoma, granulomata, amyloid, metastases
Pregnancy - intrahepatic cholestasis of pregnancy
Genetic - PFIC, benign recurrent intrahepatic cholestasis, Alagille

In children (extrahepatic conjugated hyperbilirubinaemia)

Gallstones
Primary sclerosing cholangitis
Pancreatic pathology
(Plus biliary atresia and choledochal cyst in infancy)

Consequences of obstruction

Bile salts not delivered to gut -> steatorrhoea, pale stools, fat-soluble vitamin (ADEK) malabsorption
Vitamin K deficiency -> prolonged INR that CORRECTS with parenteral vitamin K
- Distinguishes cholestasis from hepatocellular failure, where it does not correct
Bile stasis -> bacterial colonisation -> cholangitis and septicaemia
Chronic obstruction -> secondary biliary cirrhosis
Bile salts in skin/circulation -> pruritus; endotoxaemia + bile salts -> post-obstructive AKI (hepatorenal-like)

Diagnosis

Clinical

Jaundice, dark urine, pale stools, pruritus
Courvoisier law: palpable gallbladder + jaundice = malignant obstruction (pancreatic head or ampullary carcinoma) or mucocele
- Not an in-situ CBD stone - chronic stone disease leaves a fibrotic, non-distensible gallbladder
Enlarged gallbladder WITHOUT jaundice -> mucocele, empyema, gallbladder carcinoma, acute cholecystitis
Painless -> malignancy; painful + febrile -> stone/cholangitis
Look for: hepatomegaly, Virchow node, ascites, scratch marks, xanthelasma, weight loss

Bloods

ALP and GGT >> ALT/AST (cholestatic pattern)
- Isolated ALP without GGT -> bone, not biliary
Conjugated bilirubin
INR - repeat after IV vitamin K 10 mg
FBE, CRP, lipase, UEC, blood cultures
CA 19-9 - raised by obstruction itself; interpret only after decompression, and useless if Lewis-antigen negative (~5-10%)
AMA, IgG4, ANA/SMA if ducts not dilated

Imaging - in order

A. Ultrasound first - stones, duct calibre (CBD >6 mm, or >8-10 mm post-cholecystectomy), liver lesions
- Sensitive for gallbladder stones (>95%), poor for CBD stones (~25-50%) - a normal CBD does not exclude a stone
B. MRCP - non-invasive gold standard for ductal anatomy and stones
C. Endoscopic ultrasound - best for small distal stones, ampullary and small pancreatic lesions, and tissue (FNA)
D. CT (pancreatic protocol) - staging malignancy, vascular involvement, resectability
ERCP is therapeutic, not diagnostic - do not do a diagnostic ERCP; ~3-5% post-ERCP pancreatitis
PTC if ERCP fails or hilar obstruction (Klatskin)
HIDA - cystic duct patency (acute cholecystitis), bile leak

Risk stratification for a CBD stone (before ERCP)

High (-> direct ERCP): CBD stone seen on imaging, cholangitis, bilirubin >70 micromol/L with dilated CBD
Intermediate (-> MRCP or EUS first): abnormal LFTs, dilated CBD, age >55
Low (-> cholecystectomy with on-table cholangiogram)

Management

1. Cholangitis - a medical emergency

Sepsis management + IV antibiotics + BILIARY DRAINAGE
- Blood cultures, fluids, empirical amoxicillin + gentamicin (or piperacillin-tazobactam if severe/health-care associated)
- *Antibiotics alone do not treat an obstructed duct - drainage within 24-48 h, urgently if not improving or in shock*
ERCP with sphincterotomy + stone extraction/stent is the drainage of choice; PTC if ERCP impossible

2. Choledocholithiasis without sepsis

ERCP + sphincterotomy + extraction, then cholecystectomy on the same admission (recurrence otherwise ~20-25% within weeks)
Or laparoscopic cholecystectomy + bile duct exploration

3. Malignant obstruction

Stage before stenting where resection is possible - a stent degrades imaging and causes inflammation
Resectable - Whipple (pancreatoduodenectomy), hilar resection +/- liver resection
Unresectable - self-expanding metal stent (lasts longer than plastic; plastic only if resection still possible or short prognosis)
Palliative chemotherapy, coeliac plexus block for pain

4. Supportive - the details that are examined

Vitamin K parenterally before any procedure
Pruritus: cholestyramine (give 4 h apart from other drugs), then rifampicin, naltrexone, sertraline
Fat-soluble vitamin replacement, nutrition, pancreatic enzyme supplementation
Prevent post-obstructive AKI - adequate hydration peri-procedurally
Avoid nephrotoxins; adjust drug doses

5. Choledochal cyst

Complete surgical excision + Roux-en-Y hepaticojejunostomy - drainage alone leaves malignant risk
Lifelong surveillance for cholangiocarcinoma in the remnant

Associations

PSC - IBD (esp. UC), cholangiocarcinoma, colorectal cancer
PBC - Sjogren, thyroid disease, coeliac
IgG4-related disease - autoimmune pancreatitis, sclerosing cholangitis; steroid-responsive, mimics malignancy
Choledochal cyst - anomalous pancreaticobiliary junction, cholangiocarcinoma
Gallstones - obesity, rapid weight loss, pregnancy, haemolysis (pigment stones), ileal Crohn/resection, ceftriaxone, octreotide
Chronic pancreatitis - distal CBD stricture
Liver fluke (Clonorchis, Opisthorchis) - cholangiocarcinoma

Natural history & complications

Untreated cholangitis -> septic shock, hepatic abscess, death - mortality still ~10% with, far higher without, drainage
Chronic partial obstruction -> secondary biliary cirrhosis over months-years
Pancreatic head carcinoma - median survival <1 year unresected; ~20% resectable at diagnosis
Cholangiocarcinoma - often unresectable at presentation
Post-ERCP: pancreatitis 3-5%, bleeding, perforation, cholangitis
Stent occlusion - recurrent jaundice/cholangitis; plastic stents block at ~3 months and must be planned for
Choledochal cyst - cholangiocarcinoma risk persists after excision (~1-2%), far higher (up to 30%) if unexcised

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