The gallbladder and hence gallstones have a variable position
Most gallstones are asymptomatic
Appendicolith is an occasional but important X-ray feature of appendicitis
Other investigations
Ultrasound is the initial investigation of choice for suspected gallstones
Ultrasound or CT can be used to investigate appendicitis but the diagnosis is usually made clinically
Abnormal calcification also occurs in the hepatobiliary tree, and the gastrointestinal tract such as in the appendix (appendicolith).
Gallstones
Gallstones are very common. Approximately 20% of the adult population in western countries have gallstones. They can become pathological if they fall out of the gallbladder into the biliary tree.
Only 10-15% of gallstones contain enough calcium to be visible on an abdominal X-ray. If they are visible don't assume they are the cause of abdominal pain as most are asymptomatic.
Gallstones have a variable position depending on the position of the gallbladder and may be mistaken for renal stones
Unlike renal stones they are often rounded and cluster together
This X-ray also shows an incidental calcified mesenteric node which may also mimic renal stones
Appendicolith
In appendicitis the abdominal X-ray is usually normal, and is not a required investigation unless a complication such as perforation is suspected. Occasionally an appendicolith is seen. This is a small calcified stone within the appendix, and is seen in the right iliac fossa.
Although an uncommon feature of appendicitis an appendicolith is highly predictive of the diagnosis in patients presenting with abdominal pain, and is also thought to be associated with a higher risk of gangrene or perforation.
