What Are Gallstones?

Gallstones (also called cholelithiasis) form when there is an imbalance in the composition of bile, resulting in hard stones that are made of crystallized cholesterol, pigment, or a mixture of the two. Gallstones can range in size from as small as a grain of sand to as large as a golf ball. You can have one large gallstone, dozens to hundreds of smaller gallstones, or a combination of both large and small stones.

There are two types of gallstones:

• Cholesterol stones: Cholesterol stones are the result of bile that is made of too much cholesterol or bilirubin and not enough bile salts. Cholesterol stones may also form when the gallbladder fails to empty during the digestive process. These usually yellow-green gallstones are the most common type.
• Pigment stones: People who develop pigment stones are typically people who have cirrhosis of the liver, biliary tract infections, and hereditary blood disorders, including sickle cell anemia. These are all conditions that cause too much bilirubin, which is what the stones are made of. Pigment stones tend to be dark brown or black.

Symptoms are not always present, so anyone can have gallstones and not be aware of it. In fact, most people with gallstones don't have symptoms.

However, when gallstones travel into and block the ducts of your biliary tract, a sudden sharp pain is felt in the upper right or center of your abdomen. The pain that can occur with this blockage is what is often referred to as biliary colic, or a gallbladder attack. That pain, which is usually severe, can last a few minutes to several hours.

The biliary tract is the pathway between your liver and pancreas to the first part of the small intestine. The gallbladder, part of that tract, is a small, pear-shaped organ that sits under your liver on the upper right side of your body between your chest and your hips. It acts as a storehouse for bile, which is a fluid produced by your liver to help your body digest fat.

Bile helps your body digest fats and fat-soluble vitamins. After eating fats, your gallbladder contracts, pushing the stored bile into the common bile duct, which brings the liquid to your small intestine to aid digestion.

The bile stored in the gallbladder contains water, bile salts, cholesterol, fats, proteins, and bilirubin. Bile salts break up the fat that is consumed in the food we eat. The bilirubin gives the bile a yellowish-green color and our stools their brown color.

There are a variety of possible reasons why this can happen. Obesity and diets high in refined carbohydrates—such as white bread and pasta—and fat, as well as low-calorie diets and rapid weight loss, have been associated with gallstones. In addition, the possibility of developing gallstones increases with age, and women are more likely to have gallstones than men, thanks to hormonal factors. 

There are a number of tests that your doctor may perform to diagnose gallstones. Blood may be done to check for infection or inflammation, though not gallstones themselves. Imaging tests are used for that purpose, with ultrasound considered the test of choice; magnetic resonance imaging (MRI) or computerized tomography (CT) scans may also be performed.

Treatment of gallstones is only suggested if you have symptoms. If they are present—especially if there's severe pain—surgical removal of the gallbladder (laparoscopic cholecystectomy) is the most common option. 

In some cases, nonsurgical approaches may be used, but they are only considered when surgery is ill-advised. Procedures like oral dissolution therapy and extracorporeal shockwave lithotripsy (EWSL), among others, may be considered, but they are only appropriate for treating cholesterol stones.

If you suspect that you have gallstones or you have been diagnosed with the condition, keep in mind that gallbladder surgery is one of the most common surgeries for adults. Be sure to talk to your doctor about any concerns or questions you have.