JC55 (Surgery) - Biliary obstruction, epigastric mass Flashcards
Physiology of bilirubin excretion
- Source
- Forms, solubility
Bilirubin: non-toxic breakdown product of heme
□ Formed in reticuloendothelial system (RES)
Two forms:
→ Unconjugated (indirect) bilirubin:
- Not water soluble → bound to plasma protein
- Cannot be excreted directly in urine
→ Conjugated (direct) bilirubin:
- Water soluble
- Can be excreted directly in urine
Describe the physiological processing of bilirubin in the liver
Hepatic handling:
□ Unconjugated bilirubin taken up by hepatocytes, transport from blood via Ligandin or Z protein
□ Bilirubin conjugated by UDP-glucuronyl transferase
□ Secreted into bile canaliculi into duodenum
Describe the enterohepatic circulation of bilirubin
Enterohepatic circulation:
□ Conjugated bilirubin reduced into urobilinogen by intestinal flora
10% reabsorbed into portal circulation into blood»_space;secreted in kidney as urobilin
□ Unabsorbed urobilinogen oxidized into stercobilinogen and then stercobilin
Clinical manifestations of cholestatic jaundice
□ Tea-coloured urine: excretion of conjugated bilirubin in urine (bilirubinuria)
□ Pale stools: reduced stercobilin content in stools
□ Pruritus: retention of bile acid in blood, deposition in skin
Differentiate features of pre-hepatic, hepatic and post-hepatic jaundice
Differentiate clinical features of pre-hepatic, hepatic and post-hepatic jaundice
Pre-hepatic:
- Lemon-yellow jaundice
- Dark stools (↑stercobilin)
- Normal urine
Hepatic:
- Yellow jaundice
- Normal stools
- Tea-coloured urine
Post-hepatic
- Greenish jaundice
- Pale stools
- Tea-coloured urine
- Pruritus ± scratch marks
Compare the LFT in pre-hepatic, hepatic and post-hepatic jaundice
Pre-hepatic:
- ↑unconj. bilirubin
- AST/ALT normal
- ALP/GGT normal
- Albumin normal
Hepatic:
- ↑conj. bilirubin
- ↑↑↑AST/ALT (AST>ALT = toxins) (ALT>AST = viral)
- ↑ALP/GGT
- ↓albumin (if subacute)
Post-heaptic
- ↑conj. Bilirubin
- ↑AST/ALT
- ↑↑↑ALP/GGT
- Albumin normal
Causes of pre-hepatic jaundice
Haemolytic anaemia - Congenital: Membrane (spherocytosis) Metabolic (G6PD) Hb (thalassaemia) - Acquired: Immune (auto-, allo-, drug-induced) Fragmentation (microangiopathic) Infection (parasitic, bacterial) Drugs and toxins
Congenital causes
- Gilbert syndrome
- Crigler-Najjar syndrome (very rare)
Causes of hepatic jaundice
Acute liver injury
- Viral hepatitis: A, B, E
- Alcoholic hepatitis
- Drug-induced hepatitis
- Autoimmune hepatitis
Chronic liver disease
- Viral hepatitis: B, C
- Alcoholic liver disease
- Non-alcoholic fatty liver disease
- Metabolic: Wilson’s disease, haemochromatosis, α1-antitrypsin deficiency
- Autoimmune: autoimmune hepatitis
- HCC
Congenital causes
- Dubin-Johnson syndrome
- Rotor syndrome
Causes of post-hepatic jaundice
Cholangitis/RPC
Choledocholithiasis
Malignant biliary obstruction (MBO)
Benign strictures
- Post-ERCP
- Stones, chronic pancreatitis
Other obstruction
- Mirizzi syndrome
- Choledochal cyst
- Biliary atresia
Medical causes
- PBC
- PSC
- Intrahepatic cholestasis
Causes of Malignant biliary obstruction
- Cholangiocarcinoma: hilar (Klatskin tumour), CBD
- LNs: HCC, gallbladder, lymphoma, stomach
- CA head of pancreas
- CA tail of pancreas with hilar LN spread
- CA ampulla or duodenum
Investigations for suspected pre-hepatic jaundice
CBC with reticulocyte
Peripheral blood smear
LDH, haptoglobin
Direct Coomb’s test
Thick and thin blood smear - Malaria
Investigations for suspected hepatic jaundice
Clotting profile
AFP
Hepatitis serology:
Acute: anti-HBc + anti-HAV IgM
Chronic: HBsAg, anti-HCV
Autoimmune panel:
ANA, anti-smooth muscle, anti-LKM1 (for autoimmune hepatitis)
Metabolic screen:
Cu: ceruloplasmin, 24h urine Cu
Fe: iron profile
Abdominal USG:
Cirrhosis, splenomegaly, ascites
Investigations for suspected post-hepatic jaundice
U/S of HBP
ERCP/MRCP if dilated biliary system
Contrast CT abdomen - MBO
Autoimmune panel ± liver biopsy if no dilated biliary system
- AMA for PBC
- p-ANCA for PSC (if segmental dilatation on ERCP)
Confounding causes of yellow skin
Other causes of yellow skin:
→ Diet: consumption of large quantity of food with lycopene or carotene
→ Drugs: rifampicin, quinacrine, TCMs
Outline history taking for hepatic causes of jaundice
□ Chronic liver disease: Hx of chronic liver disease and its complications
□ Alcoholic: Hx of alcohol abuse
□ (Metabolic)
□ Drugs: recent drug Hx, TCM intake
□ Autoimmune: Hx of autoimmune diseases
□ Virus:
→ Feco-oral (A/E): travel Hx, ingestion of seafood
→ Blood-borne (B/C): hep B/C status, FHx of hepatitis and HCC, blood transfusion, risk factors for blood-borne transmission (transfusion, IVDU, needle stick injury, MSM)
□ (HCC)
Outline history taking for post-hepatic jaundice
□ Cholangitis:
→ Charcot’s triad: jaundice, fever, RUQ pain
→ Reynold’s pentad: jaundice, fever, RUQ tenderness, hypotension, confusion
→ Past episode (recurrent pyogenic cholangitis)
□ Choledocholithiasis (CBD stone):
→ Episodic, painful jaundice in young individuals
→ Biliary colic symptoms: episodes of severe RUQ pain
→ Hx of gallstone diseases, past surgery, ERCP
□ Malignant biliary obstruction:
→ New onset, painless, progressive jaundice in old individuals
→ CA pancreas: constant, dull, boring epigastric pain radiating to back (usually late feature)
→ Constitutional symptoms: LOA, LOW, malaise
→ Metastatic symptoms: bone pain, dyspnoea, neck lump
□ Post-ERCP jaundice
Ddx epigastric mass + jaundice
D/dx of epigastric mass + jaundice can be:
□ Hepatomegaly (mild) due to biliary obstruction
□ Hepatomegaly due to metastasis or HCC
□ LN metastasis to coeliac axis and porta hepatis
□ CA stomach with metastatic LN in porta hepatis
□ Tumour obstructing both duodenum and bile duct → distended stomach + jaundice
Physical exam for jaundice
- General examination
General examination
□ Vitals: fever, haemodynamic stability
□ General inspection: jaundice, distension, ankle oedema
□ Specific signs: xanthomata (PBC), Kayser-Fleischer rings (Wilson’s disease), hyperpigmentation (haemochromatosis)
Physical exam for jaundice
- Abdominal exam and extra screening exams
Abdominal examination
□ Scars: previous HBP surgeries
□ Stigmata of chronic liver disease: ascites, caput medusae, gynaecomastia
□ Generalized distension: ascites can be due to malnutrition, peritoneal malignancy, malignant portal vein obstruction
□ Palpable masses:
→ Hepatomegaly: primary liver tumour, metastatic disease, biliary obstruction (usually mild)
→ Enlarged palpable gallbladder: indicates MBO if a/w painless jaundice
→ Splenomegaly: portal hypertension
Digital rectal examination for pale stools
Metastatic screen: LNs, bony tenderness, respiratory examination
