What Are Gallbladder Stones? (Cholelithiasis) – Complete Guide

What exactly are gallstones?

Gallbladder stones, medically known as cholelithiasis, are solid, pebble‑like deposits that form inside the gallbladder – a small, pear‑shaped organ located just below the liver on the right side of the abdomen. The gallbladder stores bile, a digestive fluid produced by the liver that helps break down fats. When the chemical balance of bile is disturbed, particles can solidify and grow into stones over time.

Gallstones vary dramatically in size – from as small as a grain of sand to as large as a golf ball. They can be single or multiple, and their number does not necessarily correlate with symptom severity. A single large stone may cause no symptoms, while dozens of tiny stones can trigger severe pain or complications.

Gallstone composition – cholesterol vs pigment

There are two main types of gallstones, distinguished by their chemical composition:

• Cholesterol stones (75‑80%): Yellow‑green in colour, composed primarily of hardened cholesterol. They form when bile contains too much cholesterol, not enough bile salts, or the gallbladder does not empty properly. These are the most common type in Western countries.
• Pigment stones (15‑20%): Dark brown or black, composed of bilirubin (a waste product from broken red blood cells). They occur in people with high bilirubin levels – conditions like cirrhosis, haemolytic anaemia (sickle cell disease), or biliary tract infections.
• Mixed stones: Many stones have both cholesterol and pigment components.

Less common types include calcium carbonate stones (rare) and stones caused by certain medications (e.g., ceftriaxone).

How do gallstones form? (Supersaturation, nucleation, stasis)

Gallstones form through a three‑step process:

1. Supersaturation: Bile becomes overloaded with cholesterol or bilirubin beyond what bile salts can keep dissolved.
2. Nucleation: Excess cholesterol or bilirubin begins to solidify into microscopic crystals.
3. Stone growth: Over months or years, crystals aggregate and grow into visible stones. Gallbladder stasis (incomplete emptying) allows more time for growth.

Who gets gallstones? (The 5F’s and beyond)

The classic “5F’s” are a helpful mnemonic for gallstone risk factors:

• Female: Women are twice as likely as men due to oestrogen increasing cholesterol secretion.
• Fat (obesity): High body mass index increases cholesterol saturation in bile.
• Forty (age over 40): Risk increases with age, especially after 40.
• Fertile (childbearing age / multiple pregnancies): Pregnancy increases cholesterol secretion and reduces gallbladder emptying.
• Family history: Genetics play a role – gallstones run in families.

Additional risk factors include:

• Rapid weight loss or fasting (concentrates bile)
• High‑fat, low‑fibre diet
• Diabetes mellitus
• Crohn’s disease or ileal resection (reduces bile salt absorption)
• Certain medications (ceftriaxone, somatostatin analogues, fibrates)
• Haemolytic anaemias (sickle cell, spherocytosis) – pigment stones

How common are gallstones?

Gallstones are extremely common. In Western countries, the prevalence is 10‑15% in adults – meaning 1 in 7 to 1 in 10 people have gallstones. In India, the prevalence varies by region but is estimated at 2‑6% in rural areas and up to 10‑15% in urban populations, likely due to dietary changes (increased fat, refined carbohydrates). Most people with gallstones never develop symptoms.

Interactive FAQ – What are gallstones?

Disclaimer: This information is for educational purposes. If you have symptoms of gallstones (right upper quadrant pain, nausea, fever), consult a gastroenterologist or surgeon at Vivekananda Hospital.