This condition usually begins with the formation of gallstones in the gallbladder. Whether you have gallstones may depend on several factors, including inherited body chemistry, weight, gallbladder activity, and diet. Gallstones form when substances in the bile form crystal-like particles. They can range from the size of a grain of sand to the size of a golf ball. The presence of gallstones causes pressure, irritation, and may cause infection. In time, the walls of the gallbladder begin to thicken. Eventually, the gallbladder starts to shrink. These changes make it harder for the gallbladder to function properly.

Often, a bladder becomes enlarged when something blocks the urinary tract. The cause of the obstruction may gradually affect the walls of the bladder, causing them to thicken over a period of time. They may thicken enough to make the whole organ larger than normal. In some cases, the obstruction is caused by a tumor, which could be benign or malignant; sometimes bladder stones cause this issue as well. Surgery is often used to remove the obstruction in such a case, and the bladder often returns to its normal size after the treatment.