Gallstones typical features
- Hx: biliary colic or episodes of chlolecystitis. 
- Obstructive type

Gallstones pathogenesis
- small calibre gallstones -> pass through the cystic duct. 
- In Mirizzi syndrome the stone may compress the bile duct directly- <sup>one of the rare times that cholecystitis may present with jaundice</sup>

Cholangitis features
- Usu obstructive
- Charcots triad: pain, jaundice, fever

Cholangitis pathogenesis
- Ascending infection of the bile ducts usually by E. coli
- by definition occurring in a pool of stagnant bile.

Pancreatic cancer features
painless jaundice with palpable gallbladder (Courvoisier's Law)

Pancreatic cancer pathogenesis
<answer>
- Direct occlusion: distal bile duct or pancreatic duct by tumour. 

- Sometimes nodal disease at the portal hepatis may be the culprit in which case the bile duct may be of normal calibre.
</answer>

Bile duct injury pathogenesis
<answer>
- bile duct is excised
  + jaundice offers rapidly post operatively
  + often due to diff cholecystectomy 

- more insidious: bile duct stenosis &lt;- clips or diathermy injury.
</answer>

Cholangiocarcinoma
- Primary sclerosing cholangitis is a RF
- gradual onset obstructive pattern

<question>
Diagnosis 1st line 
what and what it shows
</question>
<answer>
US of liver and biliary trree

establish 
- bile duct calibre
- presence of gallstones
- may visualise pancreatic masses and other lesions. 

The most important clinical question is essentially the extent of <strong>biliary dilatation</strong> and its distribution.
</answer>

Diagnosis 1st and next
* 1st line: US liver and biliary tree
* Next if suspect
- pancreatic neoplasia: prancreatic protocol CT scan
- liver tumours and cholangiocarcinoma: MRI/MRCP. If failed, ERCP. 
- PET scans: to stage