Gallstones (often misspelled as gall stones, or gall stone) are stones that form in the gall (bile) within the gallbladder. The gallbladder is a pear-shaped organ just below the liver that stores the bile secreted by the liver.
Bile is a watery liquid made by the cells of the liver that is important for digesting food in the intestine, particularly fat.
Liver cells secrete the bile into small canals within the liver.
The bile flows through the canals and into larger collecting ducts within the liver (the intrahepatic bile ducts).
The bile then flows through the intrahepatic bile ducts out of the liver and into the extrahepatic bile ducts-first into the hepatic bile ducts, then into the common hepatic duct, and finally into the common bile duct.
From the common bile duct, there are two different directions that bile can flow.
The first direction is the common bile duct and into the intestine where the bile mixes with food and promotes digestion of food.
The second direction is into the cystic duct, and from there into the gallbladder (often misspelled as gall bladder).
Once in the gallbladder, bile is concentrated by the removal (absorption) of water. During a meal, the muscle that makes up the wall of the gallbladder contracts and squeezes the concentrated bile in the gallbladder back through the cystic duct into the common duct and then into the intestine. Concentrated bile is much more effective for digestion than the un-concentrated bile that goes from the liver straight into the intestine.
The timing of gallbladder contraction-during a meal-allows the concentrated bile from the gallbladder to mix with food.
Gallstones usually form in the gallbladder; however, they also may form anywhere there is bile; in the intrahepatic, hepatic, common bile, and cystic ducts.
Gallstones also may move about in the bile, for example, from the gallbladder into the cystic or common duct.
The majority of people with gallstones have no signs or symptoms and are unaware of their gallstones. The gallstones are "silent". The gallstones often are found as a result of tests (for example, ultrasound or X-rayexamination of the abdomen) performed while evaluating medical conditions other than gallstones.
Symptoms can appear later in life, however, after many years without symptoms. Thus, over a period of five years, approximately 10% of people with silent gallstones will develop symptoms. Once symptoms develop, they are likely to continue and often will worsen.
Gallstones are blamed for many symptoms they do not cause.
Among the symptoms gallstones do not cause are:
- dyspepsia (including abdominal bloating and discomfort after eating),
- intolerance to fatty foods,
- flatulence (passing gas or farting).
When signs and symptoms of gallstones occur, they virtually always occur because the gallstones obstruct the bile ducts.
The most common symptom of gallstones is biliary colic. Biliary colic is a very specific type of pain, occurring as the primary or only symptom in 80% of people with gallstones who develop symptoms. Biliary colic occurs when the extrahepatic ducts-cystic, (hepatic duct or common bile duct) are suddenly blocked by a gallstone.
Slowly-progressing obstruction, as from a tumor, does not cause biliary colic. Behind the obstruction, fluid accumulates and distends the ducts and gallbladder. In the case of hepatic duct or common bile duct obstruction, this is due to continued secretion of bile by the liver. In the case of cystic duct obstruction, the wall of the gallbladder secretes fluid into the gallbladder. It is the distention of the ducts or gallbladder that causes biliary colic.
Characteristically, biliary colic comes on suddenly or builds rapidly to a peak over a few minutes.
It is a constant pain, it does not come and go, though it may vary in intensity while it is present.
It lasts for 15 minutes to 4-5 hours. If the pain lasts more than 4-5 hours, it means that a complication - usually cholecystitis - has developed.
The pain usually is severe, but movement does not make the pain worse. In fact, patients experiencing biliary colic often walk about or writhe (twist the body in different positions) in bed trying to find a comfortable position.
Biliary colic often is accompanied by nausea.
Most commonly, biliary colic is felt in the middle of the upper abdomen just below the sternum.
The second most common location for pain is the right upper abdomen just below the margin of the ribs.
Occasionally, the pain also may be felt in the back at the lower tip of the scapula on the right side.
On rare occasions, the pain may be felt beneath the sternum and is mistaken for angina or a heart attack.
An episode of biliary colic subsides gradually once the gallstone shifts within the duct so that it is no longer causing obstruction.
Biliary colic is a recurring symptom. Once the first episode occurs, there are likely to be other episodes. Also, there is a pattern of recurrence for each individual, that is, in some individuals the episodes tend to remain frequent while in others they are infrequent. The majority of people who develop biliary colic do not go on to develop cholecystitis or other complications.
Gallstones are common; they occur in approximately 20% of women in the US, Canada and Europe, but there is a large variation in prevalence among ethnic groups. For example, gallstones occur 1 ½ to 2 times more commonly in Scandinavians and Mexican-Americans. Among American Indians, gallstone prevalence reaches more than 80%.
These differences probably are accounted for by genetic (hereditary) factors. First-degree relatives (parents, siblings, and children) of individuals with gallstones are 1 ½ times more likely to have gallstones than if they did not have a first-degree relative with gallstones.
Further support comes from twin studies that show that genetic factors are important in determining who develops gallstones. Among non-identical pair of twins (who share 50% of their genes with each other), both individuals in a pair have gallstones 8% of the time. Among identical pair of twins (who share 100% of their genes with each other), both individuals in a pair have gallstones 23% of the time.
There are several types of gallstones and each type has a different cause.
Cholesterol gallstones are primarily of made up of cholesterol. They are the most common type of gallstone, comprising 80% of gallstones in individuals in Europe and the Americas. Cholesterol is one of the substances that liver cells secrete into bile. Secretion of cholesterol into bile is an important mechanism by which the liver eliminates excess cholesterol from the body.
In order for bile to carry cholesterol, the cholesterol must be dissolved in the bile. Cholesterol is a fat, however, and bile is an aqueous or watery solution;fats do not dissolve in watery solutions. In order to make the cholesterol dissolve in bile, the liver also secretes two detergent-bile acids and lecithin-into the bile.
These detergents, just like dish-washing detergents, dissolve the fatty cholesterol so that it can be carried by bile through the ducts. If the liver secretes too much cholesterol for the amount of bile acids and lecithin it secretes, some of the cholesterol does not dissolve.
Similarly, if the liver does not secrete enough bile acids and lecithin, some of the cholesterol also does not dissolve. In either case, the undissolved cholesterol sticks together and forms particles of cholesterol that grow in size and eventually form gallstones.
There are two other processes that promote the formation of cholesterol gallstones though neither process is able to form cholesterol gallstones by itself. The first is an abnormally rapid formation and growth of cholesterol particles into gallstones. Thus, with the same concentrations of cholesterol, bile acids and lecithin in their bile, patients with gallstones form particles of cholesterol more rapidly than individuals without gallstones.
The second process that promotes the formation and growth of gallstones is reduced contraction and emptying of the gallbladder that allows bile to stay in the gallbladder longer than normal so that there is more time for cholesterol particles to form and grow.
Pigment gallstones are the second most common type of gallstone. Although pigment gallstones comprise only 15% of gallstones in individuals from Europe and the Americas, they are more common than cholesterol gallstones in Southeast Asia.
There are two types of pigment gallstones
- black pigment gallstones,
- brown pigment gallstones.
Pigment is a waste product formed from hemoglobin, the oxygen-carrying chemical in red blood cells. The hemoglobin from old red blood cells that are being destroyed is changed into a chemical called bilirubin and released into the blood. Bilirubin is removed from the blood by the liver. The liver modifies the bilirubin and secretes the modified bilirubin into bile.
Black pigment gallstones: If there is too much bilirubin in bile, the bilirubin combines with other constituents in bile, for example, calcium, to form pigment (so-called because it is dark brown in color). Pigment dissolves poorly in bile and, like cholesterol, it sticks together and forms particles that grow in size and eventually form gallstones. The pigment gallstones that form in this manner are called black pigment gallstones because they are black and hard.
Brown pigment gallstones
If there is reduced contraction of the gallbladder or obstruction to the flow of bile through the ducts, bacteria may ascend from the duodenum into the bile ducts and gallbladder. The bacteria alter the bilirubin in the ducts and gallbladder, and the altered bilirubin then combines with calcium to form pigment. The pigment then combines with fats in bile (cholesterol and fatty acids from lecithin) to form particles that grow into gallstones. This type of gallstone is called a brown pigment gallstone because it is more brown than black. It also is softer than black pigment gallstones.
Other types of gallstones
Other types of gallstones are rare. Perhaps the most interesting type is the gallstone that forms in patients taking the antibiotic, ceftriaxone (Rocephin). Ceftriaxone is unusual in that it is eliminated from the body in bile in high concentrations. It combines with calcium in bile and becomes insoluble.
Like cholesterol and pigment, the insoluble ceftriaxone and calcium form particles that grow into gallstones. Fortunately, most of these gallstones disappear once the antibiotic is discontinued; however, they still may cause problems until they disappear. Another rare type of gallstone is formed from calcium carbonate.
Most gallstones are silent.
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.
In younger individuals, no treatment also may be appropriate if the individuals have serious, life-threatening diseases, for example, serious heart disease, that are likely to shorten their life span.
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 (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 of food 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 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 risks associated with 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:
- It is only effective for cholesterol gallstones and not pigment gallstones.
- It works only for small gallstones, less than 1-1.5 cm in diameter.
- 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 perhaps 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.