Courvoisier's law (known as Courvoisier's sign or Courvoisier–Terrier's sign, or Courvoisier syndrome) states that a painless palpably enlarged gallbladder accompanied with mild jaundice is unlikely to be caused by gallstones. Usually, the term is used to describe the physical examination finding of the right-upper quadrant of the abdomen. This sign implicates possible malignancy of the gallbladder or pancreas and the swelling is unlikely due to gallstones. This observation is best explained as a matter of the gradual increase in gallbladder distention that occurs secondary to chronic processes versus the abrupt increase in gallbladder pressure observed in acute processes. Courvoisier's sign occurs due to the gradual (chronic) nature of the obstruction caused by cancer (e.g. pancreatic, often located in pancreatic head, cholangiocarcinoma, etc.), which gradually causes biliary back-pressure and gradually distends the gallbladder over time, without causing acute damage, thus without causing pain. Conversely, gallstones cause obstruction of the biliary tree in a more abrupt (acute) nature when the gallstone becomes suddenly lodged somewhere along the biliary tree, blocking the passage of bile. This process causes the gallbladder to distend as it contracts against an abruptly blocked/higher pressure biliary tree, resulting in acute inflammation of the gallbladder (acute cholecystitis) and right upper quadrant abdominal pain (i.e., not Courvoisier's sign). Fibrosis of the gallbladder is another chronic process that occurs due to repeated acute inflammation (i.e., chronic cholecystitis), resulting in a shrunken, fibrotic (therefore hard), and calcified gallbladder ("porcelain gallbladder"), which typically will not present with Courvoisier's sign and is diagnosed with imaging. Ludwig Georg Courvoisier's original observations, published in Germany in 1890, were not originally cited as a 'law', and no mention of malignancy or pain (tenderness) was made. These points are commonly misquoted or confused in the medical literature. Exceptions Exceptions to Courvoisier's law imply that a stone is responsible for jaundice and a non-tender, palpable gall bladder. Typically gall bladder stones form slowly which allow time for the gall bladder to become tender. The exceptions to the law are stones that dislodge and acutely block the duct distally to the hepatic/cystic duct junction: Double gallstones with one falling and blocking the common bile duct (responsible for jaundice) and one at the cystic duct (palpable non-tender gallbladder results from precisely a mucocele of the fibrotic gallbladder) Cholangiocarcinoma, Klatskin tumors, ascariasis, or recurrent pyogenic cholangitis are not exceptions to the law because they all fall under it. For example, in the