Cholelithasis, more commonly known as gallstones, are hardened deposits of bile in the gallbladder. Approximately 10 to 15% of Americans experience gallstones in their lifetime. To understand gallstones and why they develop, one needs to understand the gallbladder and how it functions

Gallbladder

The gallbladder is a small, hollow organ located beneath the liver that stores bile in high concentrations. Bile is a bitter alkaline fluid produced by the liver to support digestion. The liver sends bile into the gallbladder by means of the common hepatic duct.
When food containing fat enters the digestive tract, the intestines release cholecystokinin. The cholecystokinin causes the gallbladder to contract and release the bile from the gallbladder into the small intestines through the common bile duct to digest fats. Bile is made up of water and bile salts or acids. These acids include—taurocholic acid and glycocholic acid (derivatives of cholic acid) and taurochenodeoxycholic acid and glycochenodeoxycholic acid (derivatives of chenodeoxycholic acid).
Gallstones can be divided into two categories: cholesterol or pigment.

Cholesterol gallstones

Most gallstones, about 75%, are made up of cholesterol. Cholesterol gallstones result from biliary supersaturation caused by:

• An increased secretion of cholesterol into the gallbladder
• Gallbladder hypomotility—a case in which crystals remain in the gallbladder so long they become stones
• Accelerated cholesterol nucleation and crystallization
• Mucin (a glycoprotein component of mucus) gel accumulation

Pigment gallstones

Pigment gallstones can be black or brown depending on what they are made of.

Black pigment gallstones:

Up to 15% of gallstones are black pigment gallstones. They are caused by chronic hemolysis (rupture of red blood cells) associated with supersaturation of bile with calcium hydrogen bilirubinate and deposition of calcium carbonate, phosphate, and salt.

Brown pigment gallstones:

Nearly 10% of gallstones are brown pigment stones. They result from infections related to bile duct obstructed. Bacteria that produce β-glucuronidase, phospholipase and slime promote stone formation.

Symptoms of gallstones

Silent gallstones:

Most cases of gallstones are asymptomatic. They are often not identified until the patient undergoes imaging for other conditions. However, nearly 20% of patients with asymptomatic gallstones progress into more severe conditions. Gallstones that do not show symptoms often go untreated since there is more risk associated with its removal than with its presence. Patients are advised to monitor it.

Biliary colic:

A common symptom of gallstones is biliary colic (also known as gallstone pain or biliary pain). Biliary colic is experienced as abdominal pain. The pain is a constant, severe pain in the right upper abdomen just below the ribs, in the epigastrium, or both. The pain usually lasts between 30 minutes and 2 hours.
When the gallbladder is bloated, it is common for midline or epigastric pain to occur due to stimulation of pain fibers being felt. For a large number of patients, nearly 60%, pain is also experienced in the back and right shoulder. This pain cannot be relieved by shifting body positions or passing stool or gas.
A strong indicator of biliary pain is the experience of pain more than an hour after eating (particularly a fatty meal), in the evening or at night. This is because the gallbladder contracts and the gallstones press against the opening of the gallbladder. Once the gallbladder relaxes a few hours later, the pain dissipates. Other symptoms may accompany the pain such as nausea and vomiting.

Causes of gallstones

Gallstones form from the solidification of bile. This occurs when cholesterol or the bilirubin—a pigment generated in the liver from the breakdown of hemoglobin that is then excreted into bile—in the bile is high. What causes bile levels to become high is still relatively unknown. It is possible that other substances in the bile support stone formation. It is believed that low muscle tone may prevent the gallbladder from completely emptying which may increase bile and cholesterol levels in the gallbladder. There are several risk factors associated with gallstones such as being a female, being overweight, yoyo dieting, and certain medications.