Gallbladder

The Gallbladder: A Comprehensive Encyclopedic Reference

Overview and Definition

The gallbladder is a small hollow organ, about the size and shape of a pear, and is a part of the biliary system — also known as the biliary tree or biliary tract. It is a component of the extrahepatic biliary system where bile is stored and concentrated. Bile is a fluid formed in the liver that is essential for digesting fats, excreting cholesterol, and even possesses antimicrobial activity.

The biliary system is a series of ducts within the liver, gallbladder, and pancreas that empty into the small intestine, with both intrahepatic (within the liver) and extrahepatic (outside the liver) components. The gallbladder lies in the right upper quadrant of the abdomen, affixed to the undersurface of the liver at the gallbladder fossa. It is attached to the rest of the extrahepatic biliary system via the cystic duct.

Anatomy and Structure

Gross Anatomy

The gallbladder has a storage capacity of 30–50 ml and, in life, lies anterior to the first part of the duodenum. It is typically divided into three parts: the fundus, which is the rounded, distal portion projecting into the inferior surface of the liver in the mid-clavicular line; and the body, which is the largest part of the gallbladder.

The gallbladder concentrates the bile 10-fold by removing water and stores it until a person eats. The gallbladder receives most of its blood supply from the cystic artery, a branch of the right hepatic artery that arises from the common hepatic artery.

Histology and Microanatomy

The endothelial membrane of the gallbladder is equipped with numerous ion channels that actively absorb sodium, chloride, and bicarbonate ions. Water molecules subsequently follow the osmotic gradient generated by the ion shift, resulting in the concentration of bile. The gallbladder also produces about 15–20 ml of mucus throughout the course of each day.

Biliary Tree Architecture

The liver's cells (hepatocytes) excrete bile into canaliculi — intercellular spaces between the liver cells — which drain into the right and left hepatic ducts, after which bile travels via the common hepatic and cystic ducts to the gallbladder. Bile is discharged from the gallbladder via the cystic duct into the common bile duct and then into the duodenum, the first part of the small intestine, where it begins to dissolve the fat in ingested food. The liver excretes approximately 500 to 1,000 milliliters of bile each day, and most (95%) of the bile that has entered the intestines is resorbed in the terminal ileum and returned to the liver for reuse.

Physiological Functions

Bile Storage and Concentration

The main functions of the gallbladder are to store and concentrate bile, also called gall, needed for the digestion of fats in food. The bile that is secreted by the liver and stored in the gallbladder is not the same as the bile that is secreted by the gallbladder — during storage, bile is concentrated 3–10 fold by removal of some water and electrolytes through the active transport of sodium and chloride ions across the epithelium of the gallbladder, which creates an osmotic pressure that also causes water and other electrolytes to be reabsorbed.

Cholecystokinin-Mediated Release

When food containing fat enters the digestive tract, it stimulates the secretion of cholecystokinin (CCK) from I cells of the duodenum and jejunum. In response to cholecystokinin, the gallbladder rhythmically contracts and releases its contents into the common bile duct, eventually draining into the duodenum. The presence of fats and proteins in the intestines stimulates the release of cholecystokinin, which acts at the level of the body and neck of the gallbladder, causing simultaneous contraction of the body and relaxation of the neck.

During fasting states, the absence of cholecystokinin results in contraction of the sphincter of Oddi. Increased pressure in the biliary tree results in diversion of bile into the gallbladder where it is stored and concentrated.

Fat Digestion and Absorption

Bile emulsifies fats in partly digested food, thereby assisting their absorption. Bile consists primarily of water and bile salts, and also acts as a means of eliminating bilirubin, a product of hemoglobin metabolism, from the body. Bile is essential to absorb fats. The intestinal lining can absorb water but not fats; since fat is not dissolvable in water, we cannot absorb fats unless something makes the water and fats attach — this is the function of bile, as it can bind to both water and fat. Therefore, when we absorb water, the fats absorb with it if bile is present to link the water to the fat.

Bile is a mixture of mainly cholesterol, bilirubin, and bile salts. Bile is a complex fluid composed of bile salts, cholesterol, and other molecules, including phospholipids and lecithin. The bile salts are the breakdown products of hemoglobin, the oxygen-carrying pigment of red blood cells; they are formed in the liver and excreted into bile ducts which converge to form the main bile ducts.

Assessment of Gallbladder Health

Laboratory Tests

To find gallbladder issues, clinicians use several tests, including liver function tests, complete blood count, and pancreatic enzyme tests, as well as ultrasound imaging, HIDA scans, CT scans, MRI, and MRCP. Liver function tests check for gallbladder disease by examining AST, ALT, alkaline phosphatase, and bilirubin levels. Elevated liver enzymes such as direct bilirubin, AST, ALT, ALP, and GGT suggest a stone or blockage in the common bile duct.

Abdominal Ultrasound

Ultrasound, traditionally performed transabdominally and requiring a period of fasting, provides structural but not functional information. It is the least expensive, safest, and first-line imaging technique for visualizing the biliary system, and is also the most sensitive modality for imaging the gallbladder. Right upper quadrant ultrasound has a 90% specificity for gallstones and can detect stones as small as 2 mm, along with sludge and gallbladder polyps.

HIDA Scan (Cholescintigraphy)

A HIDA scan, or hepatobiliary scan, is an imaging procedure that tracks the flow of bile from the liver to the small intestine and evaluates gallbladder function. It can help diagnose certain conditions such as cholecystitis, biliary leak, and biliary atresia. The HIDA scan measures the gallbladder's ejection fraction (EF), which shows how much of the tracer is released when the gallbladder contracts. A normal EF is above 35–40%. The study can help distinguish acute or chronic cholecystitis versus biliary dyskinesia, a chronically hypofunctioning gallbladder.

Advanced Imaging

ERCP (endoscopic retrograde cholangiopancreatography) is both a diagnostic and therapeutic procedure used to examine and treat bile duct blockages, in which a flexible tube with a camera is inserted through the mouth and guided into the digestive tract, then a contrast dye is injected into the bile ducts for X-ray imaging. In addition to diagnosing gallbladder issues, doctors can use ERCP to remove gallstones or insert stents to relieve blockages, though it carries some risks including infection, bleeding, or mild discomfort.

Magnetic resonance cholangiopancreatography (MRCP) may be used for better visualization of the biliary tree, especially when evaluating for choledocholithiasis.

Conditions and Diseases of the Gallbladder

Gallstones (Cholelithiasis)

Gallstones are crystallized deposits forming in the gallbladder or biliary tree, primarily composed of cholesterol, bilirubin, and bile. These stones often remain asymptomatic, detected incidentally during imaging, but can lead to significant complications such as biliary colic, acute cholecystitis, cholangitis, or pancreatitis. Biliary colic manifests as intermittent right upper abdominal pain, often triggered by greasy or spicy foods, due to gallbladder contraction against obstructing stones. Gallstones result from impaired gallbladder contractility, reduced emptying, and excess cholesterol or bile salts.

Gallstones constitute a significant health problem in developed societies, affecting 10% to 15% of the adult population, meaning 20 to 25 million Americans have or will have gallstones. The resultant direct and indirect cost of gallbladder disease represents a consumption of approximately $6.2 billion annually in the U.S., constituting a major health burden that has increased more than 20% over the last three decades.

Multiple case-control studies comparing those with gallstones versus those without have shown that gallstone formation is multifactorial. Some features, such as ethnicity, genetics, advancing age, and female gender, cannot be modified, whereas others — e.g., diet, physical activity, rapid weight loss, and obesity — are modifiable.

Prevalence is inordinately high in American Indians and their admixtures and also in Northern Europeans; somewhat lower in European and American whites; intermediate in Asians and Black Americans; and quite low in Black Africans.

Acute Cholecystitis

Acute cholecystitis involves inflammation of the gallbladder, most commonly caused by obstruction of the cystic duct by a gallstone. Migration of a gallstone into the opening of the cystic duct may block the outflow of bile during gallbladder contraction. The resulting increase in gallbladder wall tension produces pain primarily in the right upper quadrant, which may be accompanied by nausea and vomiting. Cystic duct obstruction, if it persists for more than a few hours, may lead to acute gallbladder inflammation (acute cholecystitis).

Chronic Cholecystitis

Chronically, gallstones in the gallbladder may cause progressive fibrosis and loss of function of the gallbladder, a condition known as chronic cholecystitis. Chronic cholecystitis predisposes to gallbladder cancer.

Acalculous Cholecystitis

Approximately 10% of all cases of acute cholecystitis develop in the absence of gallstones, with precise figures ranging from 6–17% in different series. Acute acalculous cholecystitis particularly affects patients who have undergone recent trauma or major surgical operations, and underlying conditions of possible aetiological significance include cardiovascular disease, liver disease, systemic infections, diabetes mellitus, lupus erythematosus, and polyarteritis nodosa.

Choledocholithiasis

In some patients with gallstones, the stones will pass from the gallbladder into the cystic duct and then into the common bile duct. Most choledocholithiasis cases are secondary to the passage of gallstones from the gallbladder into the common bile duct (CBD). Primary choledocholithiasis — the formation of stones within the common bile duct itself — occurs in the setting of bile stasis, which results in intraductal stone formation. Bile flow obstructed by stones within the common bile duct leads to obstructive jaundice and possibly hepatitis; stagnant bile can also lead to bacteriobilia and ascending cholangitis.

It is estimated that common bile duct stones are present in anywhere from 1–15% of patients with cholelithiasis. The present-day treatment is endoscopic retrograde cholangiopancreatography (ERCP), or in some cases laparoscopic cholecystectomy with bile duct exploration.

Ascending Cholangitis

Ascending cholangitis, involving bacterial infiltration of the biliary system, presents with right upper quadrant pain, fever, and jaundice (Charcot triad). Persons may present with fever, hypotension or hypertension, and tachycardia. If left untreated, progressive decline includes neurologic changes and hypotension (Reynolds pentad).

Biliary Dyskinesia

Chronic acalculous gallbladder disease, also called biliary dyskinesia, is thought to be caused by motility disorders that affect the gallbladder's ability to store and release bile. The top presenting symptoms of biliary dyskinesia are abdominal pain (97%) and nausea (38%). Although the exact frequency of biliary dyskinesia is unknown, there is insufficient evidence to support a role for cholecystectomy in functional gallbladder disease at this time; patients with suspected functional biliary pain but whose intact gallbladder lacks ultrasonographic evidence of gallstones should be carefully evaluated to exclude other causes for their symptoms.

Primary Sclerosing Cholangitis (PSC)

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by fibro-inflammatory strictures and dilatations of the intra- and/or extrahepatic bile ducts, often associated with inflammatory bowel disease (IBD). The clinical course, although variable, is often progressive, leading to biliary cirrhosis and/or cancer. Intrinsic abnormalities of the gallbladder in PSC have been reported at a prevalence of 41% and include gallstones, cholecystitis, and mass lesions, i.e., polyps.

Gallbladder Cancer

Risk factors for gallbladder cancer include cholelithiasis, advancing age, chronic inflammatory conditions affecting the gallbladder, congenital biliary abnormalities, and diagnostic confusion over gallbladder polyps, in addition to ethnicity and female gender. Carcinoma of the gallbladder is more common in certain ethnic groups: Native American Indians, white Hispanics from North and South America, and those from northern India and Eastern Europe. Elsewhere in the world, the incidence is low at <2/100,000.

Gallbladder Polyps

Due to the malignant nature of polyps in half of patients with PSC, cholecystectomy is now recommended for patients with gallbladder polyps ≥8 mm, preferably at an experienced center for patients with advanced disease. Ultrasound is able to detect gallbladder polyps alongside gallstones and sludge.

Gallstone Pancreatitis

Gallstone obstruction in the proximity of the pancreatic duct may cause acute pancreatitis with symptoms of mid-epigastric pain and intractable vomiting. Complications may affect the pancreatic, biliary, hepatic, or gastrointestinal systems, making gallstones a leading cause of gastrointestinal disorders in the United States.

Dietary Factors and Lifestyle Supporting Gallbladder Function

Dietary Fiber

Fiber appears to play a meaningful role in gallbladder health. Higher intake supports healthier bile flow and is associated with a lower likelihood of stone formation in observational studies. Westernized diets that are low in fiber and high in refined carbohydrates and fat have been shown to be associated with an increased risk of gallstones. Fiber may have protective effects against gallstones by reducing intestinal transit time and reducing the production of bile acids. A diet higher in refined sugars, fructose, and fast food with insufficient fiber and vitamin C, as well as a general setting of increased insulin requirement, increases the risk of gallstones.

Omega-3 Fatty Acids

When the balance shifts toward thicker or more concentrated bile, cholesterol stones become more likely. Omega-3s appear to influence this balance in several ways: they may help keep bile less viscous, which supports more complete gallbladder emptying, and they can reduce biliary sludge, an early stage of gallstone formation. A 2019 study suggests that people with a diet rich in fish oil are less likely to develop gallstones than those who do not consume a lot of fish oil, possibly because omega-3 polyunsaturated fatty acids may help protect against the development of gallstones.

Coffee and Caffeine

Several studies show that habitual coffee consumption is associated with a reduced risk of developing gallbladder disease. There is some evidence that coffee triggers the contraction of the gallbladder. It appears likely that caffeine is largely responsible for this effect, since consumption of decaffeinated coffee is not linked to a reduced risk of developing gallbladder disease in all studies.

Vitamin C

Polyunsaturated fatty acids may assist with gallbladder emptying, and vegetable protein, vitamin C-rich fruits and vegetables, and coffee may increase gallbladder motility. Several specific nutrients play documented roles in gallstone prevention; adequate fiber intake, vitamin C, and varied plant-based foods demonstrate the strongest preventive benefits.

Herbs and Natural Ingredients: Traditional Use and Scientific Evidence

Artichoke Leaf Extract (Cynara scolymus)

Traditional Use

The therapeutic properties of artichoke preparations have been known since ancient times. The traditional use of artichoke leaf extract (ALE) in gastroenterology is mainly based upon its strong antidyspeptic actions, which are mediated by its choleretic activity. This choleretic effect has led to the popular use of artichoke extract in Europe for the treatment of mild indigestion, particularly following a meal high in fat.

Scientific Evidence

Artichoke (Cynara scolymus) leaf extract is one of the few herbal remedies for which clinical and experimental trials have complemented each other. Both experimental and clinical effects have been verified through extensive biomedical research; specifically, antioxidant, choleretic, hepatoprotective, bile-enhancing, and lipid-lowering effects have been demonstrated, which corresponded with its historical use.

Human clinical evidence: The choleretic action of artichoke extract (main ingredient: cynarin) was investigated in a randomized placebo-controlled double-blind cross-over pilot study (n=20). The effect of standardized artichoke extract administered as a single dose of 1.92 g by the intraduodenal route was studied by measuring intra-duodenal bile secretion using multi-channel probes. Thirty minutes after the test substance was administered, a 127.3% increase in bile secretion was recorded; after 60 minutes, 151.5%; and after another 60 minutes, 94.3%, each in relation to the initial value. The relevant differences for the placebo were significant to the extent of p < 0.01 and were clinically relevant.

Preclinical evidence: In an animal study designed to investigate the effects of ALE on bile flow in anaesthetised Wistar rats after acute and repeated oral administration (twice a day for 7 consecutive days), a significant increase in bile flow was observed after both acute treatment and repeated administration. The choleretic effects of ALE were similar to those of the reference compound dehydrocholic acid (DHCA). There was a strong ALE-induced increase in total bile acid concentration over the entire experiment.

It is well established that water-soluble extracts of artichoke leaves exert choleresis. When studied in vitro using primary cultured rat hepatocytes, artichoke leaf extracts not only stimulated biliary secretion, but also reestablished it when secretion had been inhibited. Furthermore, taurolithocholate-induced bile canalicular membrane distortions detectable by electron microscopy could be prevented by artichoke leaf extracts in a dose-dependent manner.

Evidence strength: The human clinical evidence for artichoke leaf extract's choleretic effect is based on a small pilot study (n=20); it is considered preliminary, though well-supported by converging preclinical data. Larger controlled human trials are needed to confirm efficacy and optimal dosing.

Milk Thistle (Silybum marianum)

Traditional Use

The scientific name for milk thistle is Silybum marianum. It is a member of the aster or daisy family and has been used by ancient physicians and herbalists to treat a range of liver and gallbladder diseases and to protect the liver against a variety of poisons.

Scientific Evidence

A systematic evidence report summarizing clinical studies of milk thistle in humans was commissioned by the National Center for Complementary and Alternative Medicine, a component of the National Institutes of Health, and sponsored by the Agency for Healthcare Research and Quality. The review found that the evidence for milk thistle's effect on liver-related markers was mixed and methodologically limited across most included studies.

Clinical practice suggests that milk thistle has a good anti-liver injury effect; however, there is a lack of evidence-based medicine supporting many of its proposed applications.

Milk thistle, artichoke, and green tea have each been studied for their beneficial effects on liver function and bile flow, and also provide antioxidant support. When combined, they may support bile sludge clearance, which is often considered an early stage of gallstone development.

Evidence strength: Milk thistle has a long history of traditional use for liver and gallbladder complaints. Clinical evidence for its direct impact on gallbladder-specific outcomes is weak and largely indirect. Its hepatoprotective effects are better studied than direct gallbladder choleretic effects, and most positive findings are from small or methodologically limited trials.

Dandelion Root (Taraxacum officinale)

Traditional Use

Traditional uses of dandelion root include addressing liver and gallbladder issues, digestive disorders, and mild fluid retention. In the folk medicine of many countries, dandelion root is regarded as a liver tonic, a substance believed to support the liver in an unspecified way. This led to its use for many illnesses traditionally believed to be caused by a "sluggish" or "congested" liver, including constipation, headaches, gout, and skin problems. The European Scientific Cooperative on Phytotherapy (ESCOP) recommends dandelion root for "the restoration of hepatic and biliary function, dyspepsia and loss of appetite."

Dandelion is traditionally used to increase appetite and bile stimulation while reducing symptoms of dyspepsia, flatulence, and gallstones. As a choleretic, it is thought to increase both bile production and flow to the gallbladder; as a cholagogue, it may exert a direct effect on the gallbladder by causing contraction.

Scientific Evidence

A choleretic effect has been observed in rats after intraduodenal administration of a dandelion extract, with bile volume per hour increasing by about one third. An alcoholic extract of the whole plant administered intraduodenally to rats increased bile secretion by 40% over the following two hours.

While preliminary studies suggest that dandelion root stimulates bile flow, no meaningful scientific evidence exists that this observed effect leads to any preceding benefits. Most evidence for dandelion root comes from traditional use and preclinical (animal and in vitro) studies showing antioxidant, anti-inflammatory, and potential hepatoprotective effects.

Evidence strength: Dandelion root for gallbladder support is preliminary and largely preclinical. Animal studies demonstrate choleretic effects, and the ESCOP monograph recognizes traditional use for biliary function. However, no well-designed human clinical trials specifically evaluating gallbladder outcomes have been published. Evidence is insufficient to make definitive claims about efficacy in humans.

Ursodeoxycholic Acid (UDCA)

Although not an herb, UDCA is a naturally occurring bile acid with significant clinical evidence. Ursodeoxycholic acid (UDCA) has the strongest evidence for improving bile quality and reducing gallstone probability in higher-risk situations. Treatment with UDCA leads to the formation of bile that is unsaturated and contains more bile salts suitable for the solubilization of cholesterol, also promoting regular bile flow and emptying of the gallbladder. A meta-analysis of randomized controlled trials showed that UDCA significantly reduces the risk of both asymptomatic and symptomatic gallstones after bariatric surgery.

Combining UDCA with omega-3s may offer additional support for cholesterol stones. This is supported by a 2024 randomized controlled trial where UDCA plus omega-3s outperformed UDCA alone.

Combination of Milk Thistle, Artichoke, and Green Tea

In a 2023–2024 interventional prospective open study, 65 consecutive adult patients (23 male/42 female; mean age 61 ± 18.7 years) diagnosed with biliary sludge in the gallbladder and/or common bile duct were enrolled. The study evaluated a combination of milk thistle, artichoke, and green tea for biliary sludge outcomes. Herbal blends such as milk thistle, artichoke, and green tea show early signals of benefit for bile flow and sludge, although more rigorous research is needed.

Evidence strength: The combination formula is studied in a preliminary open-label prospective study with no placebo control arm. Results are described as early signals; further randomized controlled trials are needed before efficacy can be confirmed.

Summary of Evidence Strength

• Artichoke leaf extract (choleretic effect): Small randomized controlled pilot study (n=20) in humans with positive findings on bile secretion; supported by multiple animal and in vitro studies. Preliminary but mechanistically plausible.
• Milk thistle (Silybum marianum): Established traditional use; Agency for Healthcare Research and Quality systematic review commissioned by NIH found mixed clinical evidence specifically for liver and biliary disease. Direct gallbladder evidence is weak.
• Dandelion root (Taraxacum officinale): ESCOP-recognized traditional use; animal studies demonstrate choleretic activity; no robust human clinical trials for gallbladder outcomes published. Evidence is preliminary.
• Dietary fiber: Observational/epidemiological evidence supports association with reduced gallstone risk; mechanism (reducing bile acid production and intestinal transit time) is well described.
• Omega-3 fatty acids: Observational and interventional data (including a 2024 RCT) support a role in reducing biliary sludge and gallstone risk, particularly in combination with UDCA.
• UDCA: Strongest clinical evidence base; meta-analysis of RCTs supports its role in gallstone prevention post-bariatric surgery.
• Caffeinated coffee: Multiple observational studies link habitual consumption to reduced gallbladder disease risk; mechanism likely involves caffeine-stimulated gallbladder contraction. Causality not definitively established.

References

• Physiology, Gallbladder — StatPearls, NCBI Bookshelf (NIH)
• Anatomy, Abdomen and Pelvis: Gallbladder — StatPearls, NCBI Bookshelf (NIH)
• Anatomy & Physiology — Gallbladder & Bile Duct Cancer, Johns Hopkins Pathology
• Gallstones (Cholelithiasis) — StatPearls, NCBI Bookshelf (NIH)
• Epidemiology of Gallbladder Disease: Cholelithiasis and Cancer — PMC, NIH
• Gallstones — PMC, NIH
• Acute Cholecystitis — StatPearls, NCBI Bookshelf (NIH)
• Choledocholithiasis — StatPearls, NCBI Bookshelf (NIH)
• Biliary Colic — StatPearls, NCBI Bookshelf (NIH)
• Biliary Dyskinesia — Is It Real? PMC, NIH
• Protective Potential of the Gallbladder in Primary Sclerosing Cholangitis — PMC, NIH
• Autoimmune Biliary Diseases: Primary Biliary Cholangitis and Primary Sclerosing Cholangitis — PMC, NIH
• Gallbladder: What Is It, Function, Location & Anatomy — Cleveland Clinic
• HIDA Scan: What It Is, Purpose, Procedure & Results — Cleveland Clinic
• Imaging Tests of the Liver and Gallbladder — Merck Manuals Professional
• Increase in Choleresis by Means of Artichoke Extract — PubMed
• Choleretic Activity and Biliary Elimination of Lipids and Bile Acids Induced by an Artichoke Leaf Extract in Rats — PubMed
• Pharmacological Studies of Artichoke Leaf Extract and Their Health Benefits — PubMed
• Anticholestatic Activity of Flavonoids from Artichoke and Their Metabolites — PubMed
• Milk Thistle: Effects on Liver Disease and Cirrhosis — AHRQ Evidence Report, NCBI Bookshelf
• The Efficacy of a Combination of Milk Thistle, Artichoke, and Green Tea in the Treatment of Biliary Sludge — MDPI Gastrointestinal Disorders
• Dandelion's Therapeutic Uses — EBSCO Research Starters
• Dietary Fiber Intake and Risk of Gallstone: A Case-Control Study — PMC, NIH
• Global Epidemiology of Gallstones in the 21st Century: A Systematic Review and Meta-Analysis — Clinical Gastroenterology and Hepatology
• The Relationship between Helicobacter pylori Infection of the Gallbladder and Chronic Cholecystitis and Cholelithiasis — PMC, NIH