Gallstones are very common - affecting approximately 20% of the population. Under normal circumstances bile (the green liquid that is essential for digesting fat) is made in the liver and passes into the gut via the common bile duct. Some of it passes down a side branch where it is stored in the gallbladder until food is ingested and at this point the gallbadder should contract. Failure to contract normally results in stagnation of the bile and eventually crystallization leading to stones.
Fortunately, in the majority of cases, they cause no symptoms whatsoever and are often picked up incidently during investigations for other conditions. In those that do experience symptoms this is typically a dull pain at the top of the abdomen and just under the ribs on the right side (biliary colic), sometimes with radiation through to the back. This is often triggered by a fatty meal as this makes the gallbladder contract. A severe attack may be associated with nausea, vomiting and fever (cholecystitis), necessitating admission to hospital. Complications such as pancreatitis are rare.
Approximately 40% of patients who have experienced an attack will suffer a subsequent attack so it is wise to seek specialist care - The gallbladder, like the appendix, is surplus to requirement and the treatment of choice is a laparoscopic cholecystectomy ie removal of the gallbladder and stones together using keyhole surgery (neither drug treatment nor shock wave therapy are effective). This generally has excellent results and allows patients to eat a normal healthy diet.