Gallstones are solid material that forms in the gallbladder or bile ducts. They are made of cholesterol, bilirubin, and calcium and range in size from a grain of sand to a golf ball. A single stone may be present, or they may exist in large numbers. Gallstones are also called choleliths.
The gallbladder is a sac-like organ that lies on the right side of the abdomen underneath the liver. The liver makes bile that is then stored in the gallbladder. Bile is a yellowish-green fluid that helps digest fats and dissolve cholesterol. It contains bile salts, fats, proteins, cholesterol, and bilirubin. When a person eats a meal containing fat, the gallbladder contracts and bile flows along the common bile duct, past the pancreatic duct that leads to the pancreas, and into the upper part of the small intestine (the duodenum) where it helps break down fat.
Gallstones form when some of the material in bile solidifies. At first, the solid particles are small and may form a semi-solid sludge in the gallbladder. Gradually particles come together to form larger solid masses. As many as 20% of Americans have gallstones, and most do not know it. These are called asymptomatic gallstones, and they do not need treatment. Sometimes the stones are incidentally discovered during imaging tests (e.g., x-rays, computed tomography [CT] scans) being done for other purposes. Whether gallstones cause symptoms depends on their size and number and whether they move out of the gallbladder and block the common bile duct or the pancreatic duct.
Gallstones are categorized by their composition, not their shape or size. Cholesterol gallstones are the most common type of gallstone found in people in Western industrialized countries. In the United States, about 80% of gallstones are of this type. They are made of hardened cholesterol with small amounts of other substances. Pigment gallstones are black or dark brown stones made primarily of calcium and bilirubin. About 15%–20% of gallstones are pigment stones. Primary bile duct stones are a third type of stone. These form directly in the bile duct instead of in the gallbladder, and they are rare.
Each year 1%–3% of Americans develop symptoms of gallstone disease. People of Northern European ancestry, Hispanics, and Native Americans are more likely to develop gallstone disease than African-Americans or Asians. Women are two to three times more likely than men to develop gallstones. The lifetime risk of a woman developing gallstones is 50%, but only 30% for a man. This difference is thought to be related to the effect of estrogen, a female hormone, on increasing the production of cholesterol.
Gallbladder surgery is one of the most commonly performed abdominal surgeries in the United States. About half a million gallbladder operations are done each year. Gallstones are uncommon in children, and when present are usually related to disorders present at birth (congenital disorders). The risk of developing gallstones increases with age. They are most common in people over age 60.
Researchers are not exactly sure why some people develop gallstones and others do not. One thought is that gallstones are more likely to develop when the gallbladder contracts infrequently or sluggishly and does not empty completely. Twin studies also suggest that heredity plays a moderate role in who develops gallstones.
What researchers do know is that certain factors increase the risk of developing cholesterol gallstones. These include:
The chance of developing pigment gallstones is increased in individuals who have diseases such as sickle-cell anemia, where there is an unusually high rate of red blood cell turnover. Bilirubin is the main component of pigment gallstones, and these diseases increase the amount of bilirubin formed in the liver.
Many people with gallstones never have any symptoms. Symptoms tend to occur when a gallstone moves out of the gallbladder and irritates or blocks the common bile duct or the entrance to the pancreatic duct. Sometimes symptoms come and go, as when stones irritating the bile duct move into the much larger small intestine.
Symptoms can include the following:
Pain can occur frequently or at long intervals. Jaundice and fever are signs of advanced gallstone disease and infection. Sudden intense pain, especially if accompanied by high fever, nausea, vomiting, jaundice, and dark urine are signs of a medical emergency. Medical care should be sought immediately. Untreated bile duct blockages can lead to perforation of the bile duct, infection, and death.
Diagnosis is made based on a physical examination and imaging studies. Ultrasound is the least invasive and often the most effective way to locate gallstones. Other imaging studies, such as plain x-rays and CT scans, may also be used. However, these diagnostic tools may fail to locate gallstones in the bile duct.
Other diagnostic tests can be used to better locate gallstones in the bile duct. A radionuclide scan, also called cholescintigraphy or a HIDA scan, uses a small amount of radioactive tracer material that is injected into a vein. A machine locates the radioactive tracer as it moves through the body and in this way can tell if a stone is blocking the entrance or exit to the gallbladder or the common bile duct. Endoscopic retrograde cholangiopancreatography (ERCP) is an endoscopic procedure use to locate, and sometimes remove, gallstones from the bile and pancreatic ducts. In this procedure, a thin tube called an endoscope is passed down the throat, through the stomach, and into the first part of the small intestine. Air and dye are then injected, which allow the physician to see the place where the bile duct empties into the small intestine. If stones are present, a special tool may be inserted through the endoscope to remove them.
By far, the most common and most successful treatment for gallstone disease is surgical removal of the gallbladder, an operation called a cholecystectomy. Removing the gallbladder has little effect on digestion. Bile simply goes directly from the liver to the small intestine instead of being stored. The difference is that the intestine receives a continuous flow of bile rather than receiving it only when it is needed. In about 1% of people, this continuous flow of bile causes mild diarrhea.
Most gallbladder surgery can be done laparos-copically. This means that surgery is done through a small cut in the abdomen instead of opening the entire abdominal cavity. A thin instrument called a laparoscope that contains a miniature video camera and a light is inserted through the cut. The surgeon uses the image from the video camera to insert small instruments through the incision and remove the gallbladder. Recovery from laparoscopic gallbladder surgery often takes only a few days.
If the gallbladder or pancreas is infected, or if there is scarring from previous surgeries, open gallbladder surgery is necessary. This involves making a large incision in the abdomen. Recovery time usually involves 5–7 days in the hospital and several weeks at home.
Some people are not healthy enough to undergo surgery. In this case, treatment options include a medication called ursodiol (Actigall) that helps dissolve cholesterol stones. However, the dissolving process can take 6–18 months. Sometimes this drug is given to people who are on medically supervised very-low-calorie diets for fast weight loss to help prevent them from developing gallstones. The other nonsurgical treatment option is sound wave therapy (extracorporeal shock wave lithotripsy). High-frequency sound waves are aimed at the gallstones to shatter them into smaller pieces. The pieces are then dissolved by the ursodiol or may pass into the small intestine without causing pain. With nonsurgical treatment, gallstones often recur. When the patient is healthy enough for surgery, gallbladder removal is usually the preferred option.
Once recovery from surgery is complete, individuals who have had their gallbladder removed can return to a normal healthy diet. High-fat foods are more likely to cause gas and diarrhea and should be limited or avoided; products containing caffeine or dairy may also cause stomach problems. To help alleviate discomfort, patients should slowly increase their fiber consumption and avoid fried or other fatty foods.
Gallbladder surgery is quite safe, although all surgery carries risk of infection, reaction to anesthesia, and unintentional damage to other tissue. Once the gallbladder is removed, no more gallstones can form. Most complications from gallstones arise when treatment is delayed and the pancreas or gallbladder becomes infected. This is a serious, potentially fatal, complication because infection can spread rapidly and overwhelm the body. Gallstone disease is responsible for about 10,000 deaths in the United States each year, of which only a few hundred are caused by surgical complications. The vast majority are caused by gallstone disease that has caused infection.
The formation of gallstones cannot be prevented. However maintaining a healthy weight, exercising regularly, and eating a diet high in whole grains and fresh fruit and vegetables and low in fat and cholesterol decreases the chance that gallstones will develop.
See also Alcohol consumption ; Calcium ; Cambridge diet ; Children's diets ; Digestive diseases ; Fad diets ; Hollywood diet ; Low-cholesterol diet ; Low-fat diet ; Obesity ; Ovolactovegetarianism ; 3-day diet ; Vegetarianism .
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American College of Gastroenterology (ACG), 6400 Goldsboro Rd., Ste. 450, Bethesda, MD, 20817, (301) 263-9000, firstname.lastname@example.org, http://www.acg.gi.org .
American Gastroenterological Association (AGA), 4930 Del Ray Ave., Bethesda, MD, 20814, (301) 654-2055, Fax: (301) 654-5920, http://www.gastro.org .
National Digestive Diseases Information Clearinghouse (NDDIC), 2 Information Way, Bethesda, MD, 20892-3570, (800) 891-5389, TTY: (866) 569-1162, Fax: (703) 738-4929, email@example.com, http://digestive.niddk.nih.gov .
Tish Davidson, AM