What are Gallstones?

Gallstones are lumps of solid material that form in the gallbladder. They usually look like small stones or gravel and can be as small as sand or as large as pebbles, sometimes filling the gallbladder, and may take years to grow. The most common ones are made up of cholesterol, which is a type of fat. Others are known as pigment stones and consist of calcium and red blood cells, which have broken down and solidified.

The gallbladder is a small pear shaped pouch about three to six inches long. It is tucked just under the liver below the right rib cage and is connected to the intestine and liver by small tubes called bile ducts. Bile ducts carry bile, a yellow-green fluid produced by your liver which contains waste products and chemicals to aid digestion. It plays a central role in helping the body digest fat. Bile acts as a detergent, breaking the fat into very small droplets so that it can be absorbed from food in your gut. It also makes it possible for your body to take up the fat-soluble vitamins A, D, E and K from the food passing through the gut. Bile is concentrated and stored in the gallbladder ready for use and is only released when we eat food.

Approximately one in ten people will develop gallstones or another gallbladder disease. It is not fully understood why some people have them and others don't but gallstones are more common in the following groups of people:

  1. Overweight women
  2. Women who have been pregnant
  3. People who have recently lost weight.

What causes gallstones?

Bile contains cholesterol, bile salts and waste products like the pigment bilirubin. Gallstones form when the usual balance of these substances is upset.

There are two basic types of gallstones:

  1. cholesterol gallstones are the most common, accounting for more than 80 percent of cases. These are formed when there is too much cholesterol in the bile. Cholesterol gallstones are usually yellowish-green in colour
  2. pigment gallstones are small and dark, and form when there is excess bilirubin in the bile. They tend to develop in people who have liver disease, infections in the bile tubes or hereditary blood disorders such as sickle-cell anaemia

How are gallstones treated?

Observation

Most gallstones are silent.

  1. If silent gallstones are discovered in an individual at age 65 (or older), the chance of developing symptoms from the gallstones is only 20% (or less) assuming a life span of 75 years. In this instance, it is reasonable not to treat the individual.
  2. Among younger individuals, no treatment also might be appropriate if the individuals have serious, life-threatening diseases, for example, serious heart disease, that are likely to shorten their life span.
  3. On the other hand, in healthy young individuals, treatment should be considered even for silent gallstones because the individuals' chances of developing symptoms from the gallstones over a lifetime will be higher. Once symptoms begin, treatment should be recommended since further symptoms are likely and more serious complications can be prevented.

Cholecystectomy

Cholecystectomy (removal of the gallbladder surgically) is the standard treatment for gallstones in the gallbladder. Surgery may be done through a large abdominal incision or laparoscopically through small punctures of the abdominal wall. Laparoscopic surgery results in less pain and a faster recovery. Cholecystectomy has a low rate of complications, but serious complications such as damage to the bile ducts and leakage of bile occasionally occur. There also is risk associated with the general anesthesia that is necessary for either type of surgery. Problems following removal of the gallbladder are few. Digestion is not affected, and no change in diet is necessary. Chronic diarrhea occurs in approximately 10% of patients.

Sphincterotomy and extraction of gallstones

Sometimes a gallstone may be stuck in the hepatic or common bile ducts. In such situations, there

usually are gallstones in the gallbladder as well, and cholecystectomy is necessary. It may be possible to remove the gallstone stuck in the duct at the time of surgery, but this may not always be possible. An alternative means for removing gallstones in the duct before or after cholecystectomy is with sphincterotomy followed by extraction of the gallstone.

Sphincterotomy involves cutting the muscle of the common bile duct (sphincter) at the junction of the common bile duct and the duodenum in order to allow easier access to the common bile duct. The cutting is done with an electrosurgical instrument passed through the same type of endoscope that is used for ERCP. After the sphincter is cut, instruments may be passed through the endoscope and up into the hepatic and common bile ducts to grab and pull out the gallstone or to crush the gallstone. It also is possible to pass a lithotripsy instrument that uses high frequency sound waves to break up the gallstone. Complications of sphincterotomy and extraction of gallstones include the general anesthesia, perforation of the bile ducts or duodenum, bleeding, and pancreatitis.

Oral dissolution therapy

It is possible to dissolve some cholesterol gallstones with medication taken orally. The medication is a naturally-occurring bile acid called ursodeoxycholic acid or ursodiol (Actigall, Urso). Bile acids are one of the detergents that the liver secretes into bile to dissolve cholesterol. Although one might expect therapy with ursodiol to work by increasing the amount of bile acids in bile and thereby cause the cholesterol in gallstones to dissolve, the mechanism of ursodiol's action actually is different. Ursodiol reduces the amount of cholesterol secreted in bile. The bile then has less cholesterol and becomes capable of dissolving the cholesterol in the gallstones.

There are important limitations to the use of ursodiol:

  1. It is only effective for cholesterol gallstones and not pigment gallstones.
  2. It works only for small gallstones, less than 1-1.5 cm in diameter.
  3. It takes one to two years for the gallstones to dissolve, and many of the gallstones reform following cessation of treatment.

Due to these limitations, ursodiol generally is used only in individuals with smaller gallstones that are likely to have a very high cholesterol content and who are at high risk for surgery because of ill health. It also is reasonable to use ursodiol in individuals whose gallstones were likely to have formed because of a transient event, for example, rapid loss of weight, since the gallstones would not be expected to recur following successful dissolution.

Extracorporeal shock-wave lithotripsy

Extracorporeal shock-wave lithotripsy (ESWL) is an infrequently used method for treating gallstones, particularly those lodged in bile ducts. ESWL generators produces shock waves outside of the body that are then focused on the gallstone. The shock waves shatter the gallstone, and the resulting pieces of the gallstone either drain into the intestine on their own or are extracted endoscopically as in sphincterotomy.