Gallstones

Gallstones are hardened deposits that form within the gallbladder, a small, pear-shaped organ beneath the liver that stores and concentrates bile — a digestive fluid that helps the body break down fat. Gallstones are extremely common, and the great majority of people who have them are never aware of it, since most gallstones cause no symptoms at all and are only discovered incidentally during imaging done for an unrelated reason.

Gallstones matter because they sit on a genuine spectrum, from entirely silent and harmless to a cause of serious, even life-threatening complications. A stone that occasionally blocks the outlet of the gallbladder causes the classic pain known as biliary colic. If a stone becomes persistently lodged, it can lead to inflammation of the gallbladder itself, or, if it migrates further into the bile duct system, to infection or inflammation of the pancreas — complications that require urgent treatment. Understanding where a particular case sits on this spectrum is central to understanding both the urgency and the right treatment.

How Gallstones Form

Bile is a mixture of cholesterol, bile salts, a fatty substance called lecithin, and bilirubin (a pigment produced when the body breaks down old red blood cells), all held in careful balance so that these substances remain dissolved. Gallstones form when this balance is disrupted:

• Cholesterol supersaturation: If the liver excretes more cholesterol than the bile salts and lecithin in bile can keep dissolved, the excess cholesterol can crystallise out of solution and gradually build into a stone. This is the mechanism behind the majority of gallstones.
• Excess bilirubin: Conditions that cause the liver to produce too much bilirubin, such as certain blood disorders, liver cirrhosis, or biliary tract infections, can lead to pigment stone formation instead.
• Impaired gallbladder emptying: If the gallbladder does not contract and empty itself effectively and regularly, bile remains stored for longer than usual and becomes more concentrated, making crystallisation more likely.

Types of Gallstones

The types of gallstone that may form in your gallbladder include:

• Cholesterol Gallstones: The most common type by far, typically yellow-green in colour, formed predominantly from undissolved cholesterol along with other bile components.
• Pigment Gallstones: Smaller, darker stones (brown or black) formed from excess bilirubin, more common in people with certain blood disorders, liver cirrhosis, or biliary tract infections.

The Spectrum of Gallstone Disease

Not all gallstones behave the same way, and the appropriate level of concern and treatment depends heavily on where a particular case falls on this spectrum.

• Asymptomatic Gallstones: Stones are present but cause no symptoms, often discovered incidentally on imaging performed for another reason. The majority of people with gallstones fall into this category, and most never go on to develop symptoms requiring treatment.
• Biliary Colic: A stone temporarily blocks the outlet of the gallbladder, causing sudden, intense pain in the upper right abdomen, often after a fatty meal, typically lasting minutes to a few hours before easing as the blockage resolves on its own. Once someone has had one episode, further episodes are common.
• Acute Cholecystitis: A stone causes a more persistent blockage, leading to inflammation and often infection of the gallbladder wall. Pain is more prolonged and severe than biliary colic, and is often accompanied by fever and marked tenderness in the upper right abdomen. Requires hospital treatment, usually including antibiotics and surgery.
• Choledocholithiasis: A stone migrates out of the gallbladder and lodges in the common bile duct, the main channel carrying bile to the intestine. Can cause jaundice (yellowing of the skin and eyes) as bile flow is obstructed, and requires the stone to be removed from the duct, typically via endoscopy.
• Cholangitis and Gallstone Pancreatitis: The most serious complications. Cholangitis is a bacterial infection of the obstructed bile duct system that can rapidly become life-threatening. Gallstone pancreatitis occurs when a stone obstructs the outlet shared by the bile duct and pancreatic duct, triggering inflammation of the pancreas. Both are medical emergencies requiring urgent hospital-based treatment.

When Gallstones Become a Medical Emergency

Cholangitis and gallstone pancreatitis deserve particular attention because they can progress quickly and carry real risk if treatment is delayed. Cholangitis classically presents with a combination of abdominal pain, fever, and jaundice — a pattern doctors call Charcot's triad — and if confusion and low blood pressure develop alongside these, it signals a more severe, rapidly progressing infection requiring immediate treatment.

Gallstone pancreatitis, meanwhile, is one of the most common causes of acute pancreatitis worldwide, and while many cases are mild and self-limiting, a meaningful proportion become severe and require intensive, multidisciplinary hospital care. Both conditions are managed with urgent endoscopic retrograde cholangiopancreatography (ERCP) to clear the obstructing stone from the bile duct, alongside antibiotics for infection and supportive care, followed by removal of the gallbladder itself once the acute episode has settled, to prevent recurrence.

The key practical takeaway is that pain alone, however severe, is rarely dangerous in itself — it is the combination of pain with fever, jaundice, or signs of being generally unwell that signals one of these more serious complications and should prompt an emergency, rather than routine, assessment.

Symptoms of Gallstones

Most gallstones cause no symptoms at all. When symptoms do occur, they typically follow a recognisable pattern:

• Sudden, intense pain in the upper right abdomen or below the breastbone, often triggered by a fatty meal
• Pain that may radiate to the right shoulder or between the shoulder blades
• Nausea and vomiting
• Episodes typically lasting minutes to a few hours

Symptoms suggesting a more serious complication include:

• Fever or chills alongside abdominal pain
• Yellowing of the skin or eyes (jaundice)
• Pain that is unusually severe, persistent, or does not settle as expected
• Dark urine or pale, clay-coloured stools

Risk Factors for Gallstones

Gallstones develop from an imbalance in bile composition or gallbladder function, and several factors make this imbalance more likely:

• Female sex: Gallstones are notably more common in women, related in part to the effect of oestrogen on cholesterol levels in bile
• Being aged 40 or older
• Being overweight or obese
• Pregnancy: Combines hormonal effects with reduced gallbladder emptying
• A sedentary lifestyle
• A diet high in fat and cholesterol and low in fibre
• Rapid weight loss, including after bariatric surgery, or very low-calorie dieting, both of which can increase cholesterol concentration in bile
• Diabetes
• Liver disease
• Family history of gallstones

How Gallstones are Diagnosed

Here are some ways you can prevent the formation of gallstones:

• Blood Tests: Liver function tests can indicate bile duct obstruction, while a raised white blood cell count suggests infection or inflammation. Pancreatic enzyme levels (amylase or lipase) are checked when gallstone pancreatitis is suspected.
• Ultrasound: The first-line and most useful imaging test for gallstones, highly effective at detecting stones within the gallbladder and signs of gallbladder wall inflammation.
• CT Scan: Used to assess for complications such as inflammation, abscess, or pancreatitis, and to evaluate the surrounding abdominal organs in more detail than ultrasound allows.
• MRCP (Magnetic Resonance Cholangiopancreatography): A specialised MRI scan that provides detailed imaging of the bile duct system, particularly useful for detecting stones that have migrated into the common bile duct, which are not always clearly seen on ultrasound
• ERCP (Endoscopic Retrograde Cholangiopancreatography): Both a diagnostic and therapeutic procedure — a scope is passed through the mouth to the point where the bile duct enters the intestine, allowing direct visualisation and removal of stones from the bile duct in the same procedure.

Reducing Your Risk of Gallstones

• Maintain a healthy, stable weight: Both obesity and rapid weight loss increase gallstone risk, so gradual, sustained weight management is preferable to crash dieting
• Eat a diet rich in fibre, including whole grains, vegetables, and legumes
• Limit high-fat, high-cholesterol foods
• Stay physically active, since regular exercise supports healthy gallbladder function and bile composition
• If planning significant, rapid weight loss (including after bariatric surgery), discuss gallstone risk with your care team, since preventive measures may be appropriate
• Manage underlying conditions such as diabetes and liver disease, which independently raise gallstone risk