Bladder stones are caused by a build-up of minerals in the bladder. They occur when the bladder does not empty completely after urination and the remaining urine becomes concentrated; this creates an environment for the minerals in the fluid to become crystals.
Sometimes these bladder stones can be expelled spontaneously while they are still very small. Other times, the stones remain in the lower bladder, without symptoms, and gradually build up into a larger stone over time.
Bladder stones can therefore remain in the bladder for some time and do not always cause symptoms. They may even be found incidentally during an X-ray examination. Some stones are almost spherical, while others may be irregularly shaped. In addition, they can measure from a few millimeters to several centimeters.
This condition is more common in men over 50.