Hello!
Courvoisier's law states that in a patient with jaundice, if there is a palpable gallbladder, it is not due to stones.
Obviously, exception to the rule will be conditions with a stone and palpable gallbladder!
The mnemonic is, "DHE exception".
D: Double impacted stone - one in CBD and one in cystic duct, with mucocele of gallbladder.
H: Large stone in Hartmann's pouch.
E: Empyema gallbladder.
The rule ain't useful if the patient doesn't have a gallbladder (absence, previous cholecystectomy) or if the gallbladder is intrahepatic.
That's all!
'DHEm' rebellious conditions breaking rules xD
-IkaN