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Biliary tract

The biliary tract, also known as the biliary system, is the integrated network of ducts and associated organs that facilitates the production, storage, transportation, and secretion of —a vital digestive synthesized by the liver. Comprising within the liver, extrahepatic ducts leading to the , the for storage, and regulatory structures like the , the biliary tract plays a central role in digestion and waste elimination. Anatomically, the system begins with microscopic canaliculi formed by hepatocytes, which coalesce into progressively larger intralobular and interlobular ducts within the liver's portal triads. These drain into the right and left hepatic ducts, which unite to form the common hepatic duct; this then joins the cystic duct from the gallbladder to create the common bile duct (CBD), measuring approximately 6-8 cm in length and less than 6 mm in diameter in adults. The CBD typically converges with the main pancreatic duct at the hepatopancreatic ampulla (ampulla of Vater) in the duodenum, where bile enters the gastrointestinal tract under control of the sphincter of Oddi to prevent reflux. The gallbladder, a pear-shaped sac attached to the liver's underside, has a capacity of about 50 mL and features mucosal folds that concentrate bile up to tenfold by absorbing water and electrolytes. Physiologically, hepatocytes produce 600-1000 mL of daily, an alkaline fluid ( 7.5-8.1) rich in bile salts, phospholipids, , , and electrolytes, which is further modified by cholangiocytes lining the ducts. 's primary functions include emulsifying dietary fats into micelles for enzymatic breakdown by lipases, enhancing absorption of fat-soluble vitamins (A, D, E, K), and excreting metabolic byproducts like excess and conjugated to prevent . Between meals, is stored and acidified in the ( 5.2-6.0); postprandial release is triggered by hormones such as cholecystokinin, with up to 95% of bile salts recycled via in the terminal for efficient reuse. This dynamic system ensures optimal nutrient assimilation while maintaining hepatic homeostasis.

Anatomy

Components of the biliary tract

The biliary tract, also known as the biliary tree, serves as the conduit for bile transport from hepatocytes in the liver to the , comprising both intrahepatic and extrahepatic components that form a branching network of ducts. This system ensures the delivery of for digestive processes, with the intrahepatic portions embedded within the liver and the extrahepatic portions extending outside the liver. Intrahepatic bile ducts originate from bile canaliculi, which are narrow tubular channels (approximately 1 μm in diameter) lined with microvilli that collect directly from hepatocytes. These canaliculi merge into cholangioles or ductules at the periphery of hepatic lobules, which then form interlobular ducts located in the portal triads alongside branches of the and hepatic artery. The interlobular ducts progressively converge into larger segmental ducts within the liver, draining into the right hepatic duct (draining segments V, VI, VII, and VIII; average length 0.9 cm, diameter 2.6 mm) and the left hepatic duct (draining segments II, III, and ; average length 1.7 cm, diameter 3.0 mm), with the caudate lobe (segment I) contributing small ducts to both. The right and left hepatic ducts unite at the to form the . The extrahepatic bile ducts begin with the , which measures 1.0–7.5 cm in length and approximately 4 mm in diameter, traveling within the hepatoduodenal ligament of the , positioned anterior to the and to the right of the . The , 3–4 cm long and about 4 mm in diameter, connects the to the at an acute angle on its right side and contains spiral mucosal folds known as the valves of Heister, which regulate flow and prevent collapse. The union of the common hepatic and s forms the , which spans 6.0–8.0 cm in length with a normal diameter of less than 6 mm, divided into segments: supraduodenal (mean external diameter 9 mm, internal 8 mm, running in the hepatoduodenal ligament), retroduodenal (posterior to the first part of the ), retropancreatic (behind the pancreatic head), and intrapancreatic (within the pancreatic ). The is a pear-shaped reservoir attached to the undersurface of the liver in the cystic between segments and V, measuring 7–10 cm in length and up to 4 cm in width, with a capacity of 30–50 mL. It consists of three main parts: the fundus (the widest, rounded distal portion projecting beyond the liver edge), the body (the central portion that contacts the liver and ), and the neck (tapering proximally into the before connecting to the ). The organ lies in the right upper quadrant, with its inferior surface covered by and superior surface adherent to the liver without a distinct capsule. At its termination, the common bile duct joins the main pancreatic duct to form the hepatopancreatic ampulla (ampulla of Vater), which opens into the second part of the duodenum at the major duodenal papilla. The sphincter of Oddi, a complex of circular smooth muscle fibers surrounding the ampulla and distal portions of both ducts, measures about 4 mm in internal diameter at the ampulla and regulates the flow of bile and pancreatic secretions into the duodenum while preventing reflux. The common bile duct runs posteriorly to the first part of the duodenum and the head of the pancreas before penetrating the duodenal wall obliquely.

Vascular supply and innervation

The arterial supply to the biliary tract primarily derives from branches of the , which originates from the celiac trunk. The and receive blood from the , a branch of the right hepatic artery, while the is supplied by the posterior superior pancreaticoduodenal artery inferiorly and retroduodenal branches superiorly; the supraduodenal portion of the has a relatively sparse arterial network, rendering it vulnerable to ischemia. The is primarily supplied by the , a branch of the right hepatic artery; anatomical variations may include accessory cystic arteries arising from other branches such as the . Venous drainage parallels the arterial supply through epicholedochal and paracholedochal plexuses. The cystic vein drains the directly into the or its right branch, while hepatic ducts empty via tributaries of the ; the paracholedochal plexus connects to the and gastrocolic trunk, facilitating efficient return of nutrient-rich blood from the digestive tract. Lymphatic drainage begins at initial nodes along the , known as cystic nodes, and proceeds to hepatic nodes at the , then to celiac and peripancreatic nodes, ultimately converging at the ; this pathway is clinically significant in the spread of metastases from biliary malignancies. The gallbladder lymphatics follow superior and inferior routes, with the superior path along the and hepatic artery to celiac nodes, and the inferior to nodes near the and . Innervation of the biliary tract involves both autonomic divisions and an intrinsic . Sympathetic fibers arise from the celiac and superior mesenteric plexuses via (originating from spinal segments T7-T9), providing inhibitory control over the and ductal . Parasympathetic innervation comes from the vagus nerve's hepatic branch, promoting secretory activity and gallbladder contraction, often modulated by hormones like cholecystokinin. The within duct walls coordinates local reflexes for and .

Histological features

The biliary tract's histological structure is adapted for bile transport, storage, and modification, featuring specialized epithelia and supporting tissues. , forming part of the portal triads alongside hepatic arteries and portal veins, are lined by cholangiocytes that vary by duct size: cuboidal in smaller interlobular and septal ducts (15–300 μm diameter), transitioning to low columnar in larger area, segmental, and hepatic ducts (>300 μm). These cholangiocytes possess microvilli, tight junctions, and primary cilia for sensory functions, enabling selective permeability and fluid regulation. Peribiliary glands, present in larger intrahepatic and all extrahepatic ducts, consist of mucous and serous acini that secrete bicarbonate-rich fluid to neutralize acidic duodenal contents. Extrahepatic ducts, including the common hepatic, cystic, and common bile ducts, exhibit a pseudostratified or simple columnar epithelium with interspersed goblet cells for mucin production, supported by a lamina propria of loose connective tissue containing blood vessels, lymphatics, and occasional inflammatory cells. Subepithelial layers include a thin muscularis mucosae of longitudinal smooth muscle fibers, a submucosa with tubuloacinar mucous glands (more prominent in the common bile duct), and an outer muscularis of intermingled circular and longitudinal smooth muscle bundles facilitating peristalsis. These ducts lack a serosa, being enveloped by adventitia except at the intraduodenal portion where partial serosal covering occurs; the peribiliary vascular plexus, derived from hepatic artery branches, nourishes the epithelium. The mucosa comprises tall, with prominent microvilli for absorption and concentration of , forming rugose folds that increase surface area without goblet cells in the normal state. Beneath lies a of rich in capillaries, lymphatics, and leukocytes, with deep invaginations known as Rokitansky-Aschoff sinuses extending into the to facilitate . Absent a , the wall features a thin, disorganized muscularis of fibers oriented longitudinally, circularly, and obliquely for powerful contractions, covered externally by serosa (except the hepatic attachment) or . At the distal end, the consists of circularly arranged fibers encircling the intramural portions of the common and main pancreatic ducts, providing a high-pressure (–35 mmHg) to regulate and pancreatic juice flow into the . The smallest biliary elements, (1–2 μm), form intercellular channels between glycogen-rich hepatocytes, sealed by tight junctions to direct toward cholangiocytes without paracellular leakage. These features collectively support efficient handling, with cholangiocytes modifying composition through ion transport linked to production processes.

Physiology

Bile production and composition

Bile is primarily produced by hepatocytes in the liver, which synthesize the majority of its organic components, including 80-90% of acids, , and . Cholangiocytes lining the bile ducts contribute up to 40% of bile volume through the of and water, modifying the initial hepatic bile. In adults, the liver produces approximately 600-1200 mL of bile daily, with about 95% of bile acids recycled via to maintain efficient . The composition of hepatic bile is approximately 97% water, with the remaining solids consisting mainly of bile salts (about 50% of solids, such as cholic acid and ), phospholipids (primarily ), solubilized by bile salts, conjugated bilirubin derived from breakdown, electrolytes (including Na⁺, K⁺, Cl⁻, and HCO₃⁻), , and immunoglobulins. This watery, alkaline fluid (pH 7.5-8.0) is achieved through cholangiocyte secretion of , which neutralizes acidity and facilitates fat emulsification in the intestine. Primary bile acids are synthesized from in hepatocytes via the classic pathway, initiated by the rate-limiting cholesterol 7α-hydroxylase (CYP7A1), a , leading to the formation of cholic acid and . These primary acids are then conjugated with or in the to enhance solubility and reduce toxicity, forming salts that are actively transported into bile canaliculi. , a byproduct of , undergoes in hepatocytes by (UGT1A1) to produce water-soluble conjugated for safe excretion. Hepatic bile composition varies between fasting and postprandial states; during , bile flow is lower and more dilute, while postprandial stimulation increases secretion rates, resulting in bile with higher concentrations of bile acids and electrolytes to support .

Storage, concentration, and release

The gallbladder functions as a for produced by the liver, storing 30 to 50 mL of concentrated during states, with filling occurring at low pressure through the from the hepatic bile ducts. This storage capacity allows for the accumulation of between meals, preventing continuous low-volume drainage into the intestine and enabling efficient deployment during . The low-pressure inflow is facilitated by the relaxed during interdigestive phases, ensuring gradual accumulation without undue strain on the biliary system. Bile concentration within the gallbladder is achieved primarily through active transport of sodium ions (+) and ions across the , driven by +/+- pumps, which creates an osmotic gradient for passive . This process reduces the bile volume by 5- to 10-fold, from the initial hepatic secretion of approximately 500-1000 mL per day to a more viscous, lipid-rich form, while organic components like , salts, and phospholipids remain solubilized in micelles and vesicles. The absorptive , featuring microvilli and tight junctions, enhances this efficiency, resulting in that is hypertonic relative to and optimized for emulsification. The release of stored bile is triggered postprandially by the cholecystokinin (CCK), secreted from duodenal I-cells in response to ingested fats and proteins, which binds to receptors on gallbladder to induce contraction; this is augmented by vagal parasympathetic neural stimulation. Gallbladder emptying typically expels 50-80% of its contents within 30-60 minutes, propelling through the cystic and common bile ducts toward the at a rate of 1-2 mL/min. Concurrently, CCK and mediate relaxation of the , a valve at the , allowing unimpeded flow into the intestinal lumen. Between meals, interdigestive refilling occurs via continuous basal hepatic secretion, often termed the hepatic pump, maintaining reservoir function. Impaired or in these mechanisms can promote stasis, elevating the risk of formation through and of solutes.

Enterohepatic circulation

The represents a highly efficient for bile acids, enabling their repeated utilization in while minimizing hepatic synthesis demands. Following release into the , bile acids facilitate the emulsification and of dietary fats by forming micelles that enhance lipid solubility and absorption in the . Approximately 95% of these bile acids are reabsorbed primarily in the terminal through mediated by the apical sodium-dependent bile acid transporter (ASBT, also known as SLC10A2), which is expressed on the apical membrane of ileal enterocytes. This reabsorption prevents excessive loss and supports the conservation of the pool. Reabsorbed bile acids enter the bloodstream and are transported back to the liver, where they are efficiently taken up by hepatocytes via the basolateral sodium-taurocholate cotransporting polypeptide (NTCP, SLC10A1). Once inside hepatocytes, bile acids are resecreted into the bile canaliculi through the bile salt export pump (BSEP), re-entering the biliary tract to complete the cycle. This portal vein-mediated return ensures rapid recirculation, with the process occurring 4 to 12 times per day in humans, handling approximately 20 grams of bile acids daily despite a relatively small total pool size of 2 to 4 grams. Fecal accounts for only 0.2 to 0.6 grams per day, which is compensated by hepatic synthesis to maintain pool . The efficiency of this circulation is tightly regulated by feedback mechanisms to prevent overaccumulation or depletion of bile acids. In the ileum, bile acids activate the farnesoid X receptor (FXR), which induces expression of fibroblast growth factor 19 (FGF19); this is secreted into the portal circulation and signals the liver to inhibit the rate-limiting cholesterol 7α-hydroxylase (CYP7A1), thereby suppressing bile acid synthesis. Hepatic FXR also contributes to this by directly repressing CYP7A1 transcription in response to recirculating bile acids. These regulatory pathways ensure that the bile acid pool remains stable, with the entire circulatory process supporting multiple daily cycles over a typical turnover period of 1 to 2 days per before potential loss. Disruption of , such as through ileal resection, impairs ASBT-mediated reabsorption, leading to increased delivery to the colon and subsequent due to secretory effects on colonic mucosa. In severe cases, excessive fecal loss depletes the pool, promoting supersaturation in and elevating the risk of (lithogenesis) formation, as hepatic synthesis often fails to fully compensate. Such interruptions highlight the circulation's role in maintaining digestive and metabolic balance.

Embryology

Embryonic development

The biliary tract originates from the endodermal , which buds from the ventral wall of the during the third to fourth week of . This gives rise to the liver parenchyma, intrahepatic and extrahepatic bile ducts, , and ventral , establishing the shared embryological lineage of the hepatobiliary and pancreatic systems. Duct formation begins with the proliferation of hepatic cords from the cranial portion of the , which canalize to form the between weeks 6 and 8. The extrahepatic ducts develop through elongation of the ventral bud, with the initially solidifying and then recanalizing by week 12. The arises as a caudal outgrowth from the hepatic around week 5, becoming recognizable as a distinct shortly thereafter. Key developmental milestones include the formation of the ductal plate around week 8, induced by interactions with the branching , which drives remodeling through duplication and tubulogenesis between weeks 8 and 12. By week 10, the right and left hepatic ducts separate, contributing to the intrahepatic arborization that continues until birth. The emerges from the duodenal around week 10, with muscular differentiation progressing through week 16 and nearing completion by week 28. The extrahepatic biliary system achieves maturity by week 12, while full intrahepatic duct arborization occurs by birth. Molecular regulators orchestrate hepatobiliary specification and ductal , with transcription factors such as Hhex, , and Foxa2 playing pivotal roles. Hhex is essential for hepatoblast differentiation and bile duct , Sox9 controls the timing of asymmetric tubule maturation in intrahepatic ducts, and Foxa2, often in concert with Foxa1, regulates biliary . signaling, involving receptors like Notch2 and ligands such as Jagged1, promotes biliary epithelial cell fate and ductal branching, ensuring proper tubulogenesis.

Congenital anomalies

Congenital anomalies of the biliary tract encompass a range of structural birth defects arising from disruptions in embryonic development, particularly during the recanalization of bile ducts around the 8th to 12th week of . These anomalies often manifest as obstructions, dilations, or absences in the intrahepatic or extrahepatic biliary structures, leading to early-onset , , and potential liver damage if untreated. While most are sporadic, some have genetic underpinnings, and their collective incidence varies by region, with higher rates reported in Asian populations compared to Western ones. Biliary atresia represents the most common and severe congenital anomaly of the biliary tract, characterized by the failure of recanalization of the extrahepatic bile ducts, resulting in progressive and obliteration. It occurs in approximately 1 in 10,000 to 15,000 live births worldwide, with higher incidence in (up to 1 in 5,000). Two main types are recognized: the fetal or embryonic form (about 10-20% of cases), which presents at birth with and associated malformations like polysplenia; and the perinatal form (80-90%), which develops postnatally and leads to between 2 and 8 weeks of age. Without intervention, such as the Kasai portoenterostomy performed ideally before 60 days of life—achieving bile drainage success in about 50% of early cases—infants face rapid progression to biliary cirrhosis and the need for . Choledochal cysts are congenital dilations of the ducts, often linked to an anomalous pancreaticobiliary that allows reflux of pancreatic enzymes into the biliary tree, causing weakening and cystic expansion. Their incidence is estimated at 1 in 100,000 to 150,000 live births in Western populations and approximately 1 in 1,000 in Asian populations. The Todani classification delineates five types: Type I ( dilation of the extrahepatic duct, 80-90% of cases), Type II (), Type III (choledochocele), Type IV (multiple intra- and extrahepatic cysts), and Type V (intrahepatic dilation, akin to ). These cysts predispose to recurrent cholangitis and carry a lifetime risk of of 20-30% if not excised, emphasizing the need for early surgical management to mitigate infectious and malignant complications. Alagille syndrome is a multisystem featuring paucity of , resulting from mutations in the JAG1 gene (94% of cases) or NOTCH2 gene (1-2%), which disrupt signaling critical for biliary development. It affects about 1 in 30,000 to 70,000 live births and manifests with alongside cardiac defects (e.g., pulmonary artery stenosis in 90%), characteristic facial features (broad forehead, pointed chin), and skeletal abnormalities (butterfly vertebrae). The intrahepatic biliary leads to chronic , pruritus, and xanthomas, with variable severity influenced by the specific mutation type. Other notable congenital anomalies include biliary hypoplasia, often seen in syndromic contexts like , where there is underdevelopment of intrahepatic ducts leading to impaired flow. Caroli disease involves saccular ectasia of intrahepatic ducts due to abnormal remodeling, with an estimated incidence of 1 in 1,000,000; it predisposes to cholangitis and stone formation from recurrent infections. , a rare absence of the gallbladder, occurs in 0.01-0.06% of the population and may be isolated or associated with other biliary malformations, typically presenting asymptomatically but occasionally with or .

Clinical significance

Biliary tract disorders

The biliary tract is susceptible to several acquired disorders, primarily stemming from imbalances in bile composition, obstruction, , or autoimmune processes. These conditions often manifest with symptoms related to biliary obstruction or , such as , , and fever, and can lead to significant morbidity if complications arise. Gallstones, or cholelithiasis, represent the most common biliary disorder, affecting a substantial portion of the adult population worldwide. Cholelithiasis involves the formation of crystallized deposits in the or biliary tree, predominantly composed of (accounting for approximately 80% of cases in Western populations) or in pigment stones. The arises from supersaturation of with , impaired gallbladder motility, and nucleation factors, leading to stone precipitation. Risk factors include the classic "4F's": female sex, age over forty, (fat), and (multiple pregnancies), alongside rapid , , and hemolytic disorders. Epidemiologically, gallstones affect 10-15% of adults in developed countries, with a of about 20 million individuals in the United States alone, predominantly women. Most cases remain , but complications such as —characterized by episodic right upper quadrant pain radiating to the back—and acute , involving and potential perforation, occur in 10-20% of affected individuals. Biliary atresia is a rare but critical congenital disorder characterized by progressive obliteration of the extrahepatic bile ducts, leading to , cholangitis, and if untreated. It affects approximately 1 in 10,000 to 15,000 live births, with higher incidence in Asian populations, and manifests in infancy with and acholic stools. Early and are essential to restore bile flow and prevent end-stage . Choledocholithiasis refers to gallstones migrating into the common bile duct, often precipitating secondary conditions like acute cholangitis. The etiology typically involves stones obstructing bile flow, allowing bacterial ascension from the duodenum, with Escherichia coli as the most common pathogen (isolated in up to 50% of cases). Pathophysiologically, this obstruction leads to bile stasis, increased intraductal pressure, and bacterial proliferation, resulting in suppurative infection and potential sepsis. Symptoms include the Charcot's triad of fever, jaundice, and right upper quadrant pain, present in 50-70% of patients; severe cases may progress to Reynolds pentad with hypotension and altered mental status. Epidemiologically, choledocholithiasis complicates 1-15% of cholelithiasis cases, with rates up to 10-20% in symptomatic gallstone patients, with acute cholangitis occurring in 6-9% of hospitalized individuals with gallstone disease. Untreated cholangitis carries a mortality rate of up to 50%, driven by septic shock and multi-organ failure. Cholangiocarcinoma, a highly aggressive arising from cholangiocytes lining the bile ducts, accounts for 10-25% of all hepatobiliary malignancies. Its etiology involves chronic inflammation and cellular injury leading to dysplasia, with key risk factors including (PSC), chronic , and parasitic infections such as liver flukes ( or ) in endemic areas. Pathophysiologically, oncogenic mutations (e.g., in , TP53) accumulate amid persistent biliary irritation, resulting in desmoplastic tumors that obstruct ducts and invade locally. Intrahepatic, perihilar (Klatskin tumors at the hepatic duct bifurcation, comprising 50-60% of extrahepatic cases), and distal subtypes differ in presentation, but common symptoms include painless , weight loss, pruritus, and due to biliary obstruction. The global incidence is 1-2 per 100,000, with higher rates in (up to 90 per 100,000 from fluke-related cases) and a rising trend in Western countries linked to . is poor, with 5-year survival under 10% for advanced disease. Primary sclerosing cholangitis (PSC) is a chronic, progressive cholangiopathy characterized by autoimmune-mediated inflammation and of intra- and extrahepatic ducts. The etiology remains idiopathic but involves immune dysregulation, with 70-80% of cases associated with (IBD), particularly , suggesting a gut-liver axis role. Pathophysiologically, periductal leads to multifocal strictures, stasis, and recurrent cholangitis, culminating in biliary cirrhosis, , and end-stage in 50% of patients over 10-15 years. Symptoms often include fatigue, pruritus, and right upper quadrant pain; and emerge in advanced stages. Epidemiologically, PSC has an incidence of approximately 1 per 100,000 in Northern European populations, predominantly affecting males (2:1 ratio) aged 30-40, with a cumulative risk of of 10-20%. In contrast, (PBC) targets small through autoimmune destruction, primarily affecting women. It is characterized by lymphocytic infiltration and progressive nonsuppurative cholangitis, with antimitochondrial antibodies (AMA) present in 90-95% of cases, indicating an autoimmune etiology possibly triggered by environmental factors in genetically susceptible individuals (e.g., HLA associations). Pathophysiologically, ductopenia leads to , copper accumulation, and , advancing to in untreated patients. Early symptoms are (affecting 65%) and pruritus (55%), followed by and in later stages. The incidence is 2-4 per 100,000, with a strong female predominance (9:1 ratio) and peak onset at 40-60 years, more common in Northern European descent populations.

Diagnostic approaches

Diagnosis of biliary tract disorders begins with a thorough clinical , focusing on patient history and . Common presenting symptoms include , right upper quadrant , and fever, which may suggest conditions such as choledocholithiasis or acute cholangitis. tests are essential for initial assessment, including (LFTs) that typically reveal elevated total , (ALP), and gamma-glutamyl transferase (GGT), indicating . Additional tests may include serum amylase or lipase to evaluate for associated and blood cultures if is suspected. Imaging modalities form the cornerstone of biliary tract diagnostics, with abdominal ultrasound serving as the first-line investigation due to its non-invasive nature and high sensitivity for detecting gallstones, approximately 90%. can identify (CBD) dilatation, defined as greater than 6 mm in diameter, as well as gallbladder wall thickening exceeding 3 mm, which may indicate or obstruction. For more complex cases, advanced imaging techniques are employed. Computed tomography (CT) and (MRI) are useful for identifying masses, stones, or vascular involvement in the biliary tract. (MRCP) provides non-invasive visualization of the biliary ducts with high accuracy, around 95%, making it particularly valuable for delineating strictures or stones without procedural risks. (ERCP) offers both diagnostic and therapeutic capabilities, allowing direct visualization of the and biopsy sampling, though it carries a 5% risk of post-procedure and is thus reserved when intervention is anticipated. MRCP is generally preferred over ERCP for purely diagnostic purposes to minimize complications. Additional specialized tests enhance diagnostic precision in select scenarios. Hepatobiliary iminodiacetic acid (HIDA) assesses gallbladder function by measuring ; values below 35% suggest . (EUS) excels at detecting small lesions or early malignancies in the biliary tract and periampullary region, with sensitivity up to 90% for such abnormalities. Liver biopsy may be required for confirming (PBC) or (PSC), often in conjunction with serologic testing for antimitochondrial antibodies (AMA), which are positive in over 90% of PBC cases. Specific diagnostic criteria guide evaluation of acute cholangitis, as outlined in the Tokyo Guidelines, which require evidence of (e.g., fever or elevated white blood cell count), (e.g., or elevated /ALP), and imaging findings of biliary dilatation or . This triad achieves high diagnostic accuracy, with sensitivity around 88% and specificity 78%.

Treatment and management

The treatment and management of biliary tract disorders encompass a range of medical, endoscopic, and surgical interventions tailored to the underlying condition, such as gallstones, cholangitis, (PBC), (PSC), and malignancies. Medical management forms the cornerstone for chronic cholestatic conditions like PBC and PSC. (UDCA), administered at 13-15 mg/kg/day, is the first-line therapy for PBC and improves (LFTs) in approximately 60% of patients, enhancing transplant-free survival. In PSC, UDCA may modestly improve LFTs but lacks strong evidence for altering disease progression. For acute cholangitis, intravenous antibiotics such as piperacillin-tazobactam are recommended to cover enteric pathogens, with prompt biliary decompression to resolve infection. due to gallstones is managed with analgesics, prioritizing nonsteroidal anti-inflammatory drugs (NSAIDs) like for pain relief, while avoiding opioids to minimize spasm. Endoscopic interventions are pivotal for obstructive pathologies. Endoscopic retrograde cholangiopancreatography (ERCP) achieves successful stone extraction and sphincterotomy in 85-95% of cases for choledocholithiasis, with complications including post-ERCP occurring in 3-5% of procedures. Biliary stenting via ERCP provides palliation for strictures and malignancies, improving in over 80% of patients with unresectable . For cases where ERCP fails (5-10% of attempts), (EUS)-guided biliary drainage offers technical success rates of 90-95% and clinical success in 92%, serving as an alternative for distal obstructions. Percutaneous transhepatic cholangiography (PTC) is employed when endoscopic approaches fail, achieving drainage in 85-90% of malignant obstructions. Surgical options address definitive correction of structural issues. Laparoscopic remains the gold standard for symptomatic gallstones, with success rates exceeding 95% and approximately 90% of procedures performed outpatient; , approximately 750,000-1,000,000 such operations occur annually (as of 2024). For localized , offers the best chance of cure, with 5-year survival rates of 20-40% in resectable cases. In infants with , the Kasai portoenterostomy procedure restores bile flow in 50-60% of cases if performed before 60 days of age, delaying the need for transplantation. Advanced and recent therapies target refractory or end-stage disease. , a farnesoid X receptor agonist approved by the FDA in 2016, is used as second-line treatment for PBC patients unresponsive to UDCA, reducing levels by 10-20% in non-responders. Immunosuppressants like may be added for overlap syndromes, though evidence is limited. is curative for end-stage PBC and , with 5-year survival rates of 80-85%; eligibility often requires a (MELD) score greater than 15 in decompensated cases.

References

  1. [1]
    Physiology, Biliary - StatPearls - NCBI Bookshelf
    The biliary system refers to bile production, storage, and secretion via the liver, gallbladder, and bile ducts. Bile ducts are categorized into ...Introduction · Cellular Level · Function · Related Testing
  2. [2]
    Anatomy, Abdomen and Pelvis: Biliary Ducts - StatPearls - NCBI - NIH
    Structure and Function. The primary function of the biliary tract is to transport and release the bile. The gallbladder stores and concentrates bile. Bile ...
  3. [3]
    Biliary Tract Anatomy and its Relationship with Venous Drainage - NIH
    Biliary tract is composed of intrahepatic and extrahepatic components. Intrahepatic biliary drainage system parallels the portal venous and hepatic arterial ...
  4. [4]
    Anatomy, Abdomen and Pelvis: Gallbladder - StatPearls - NCBI - NIH
    The normal common bile duct diameter varies from 4 mm to 7 mm. Dilation of this duct usually indicates a distal obstruction from a common bile duct stone, ...Missing: capacity | Show results with:capacity
  5. [5]
    Surgical anatomy of the biliary tract - PMC - NIH
    The lymphatic drainage distributes into two pathways: one superiorly with lymph nodes along the cystic duct, hepatic artery, and celiac axis; one inferiorly ...
  6. [6]
    Hepatic Nervous System and Neurobiology of the Liver - PMC
    Studies have described an efferent role for sympathetic and parasympathetic nerves innervating the biliary epithelium (5, 51). Cholangiocytes have been ...
  7. [7]
    Surgical anatomy of innervation of the gallbladder in humans and ...
    The branches innervating the GB originate from the anterior hepatic plexus, and run along the cystic duct (CD) and the cystic artery (CA). The hepatic divisions ...Missing: venous drainage
  8. [8]
    Functional Anatomy of Normal Bile Ducts - PMC - NIH
    The biliary tree is a complex network of conduits that begins with the canals of Hering and progressively merges into a system of interlobular, septal, and ...Bile Ducts And Bile... · Bile Ducts And Innervation · Bile Ducts And...
  9. [9]
    Peribiliary glands: development, dysfunction, related conditions and ...
    Peribiliary glands are minute structures that are distributed along the intrahepatic large bile ducts, extrahepatic bile duct, and cystic duct.
  10. [10]
    Common Bile Duct | Liver and Gallbladder - Histology Guide
    Histology of the common bile duct - mucosa (simple columnar epithelium, lamina propria), mucus glands, and adventitia.
  11. [11]
    Anatomy, histology & embryology - Pathology Outlines
    Sep 14, 2023 · Gallbladder wall is 1 - 2 mm thick and composed of mucosa, muscularis propria and serosa; No muscularis mucosae or submucosa is present ...
  12. [12]
    Anatomy, Abdomen and Pelvis, Sphincter of Oddi (Hepatopancreatic ...
    Jul 4, 2023 · The sphincter of Oddi is a concentric ring of muscle originating from the mesenchyme surrounding the pre-ampullary portion of the bile and ...
  13. [13]
    Physiology, Bile Secretion - StatPearls - NCBI Bookshelf
    Cholesterol catabolism by hepatocytes results in the synthesis of the 2 major primary bile acids, cholic acid, and chenodeoxycholic acid. This process involves ...
  14. [14]
    Biology of Cholangiocytes: From Bench to Bedside - PMC - NIH
    THE MECHANISMS OF DUCTAL BILE FORMATION. As mentioned earlier, cholangiocytes can contribute up to 40% of the daily bile output. In the bile duct ligated rat ...
  15. [15]
    Bile Flow - an overview | ScienceDirect Topics
    Adult humans produce approximately 600 to 1200 mL of bile per day. In a two-stage process, bile is initially secreted by hepatocytes into the biliary canaliculi ...
  16. [16]
    Bile: What It Is, Where It's Made & What It Does - Cleveland Clinic
    May 13, 2024 · What is bile made of? · Cholesterol. · Bile salts (bile acids). · Water. · Phospholipids (complex fats that contain phosphorus). · Bilirubin. · Body ...Overview · Anatomy · Conditions And DisordersMissing: hepatic | Show results with:hepatic<|control11|><|separator|>
  17. [17]
    Bile - an overview | ScienceDirect Topics
    The pH of bile ranges between 7.8 and 8.6 and its relative density is 1.010. Hepatic bile contains ∼2.5–3.5% solid matter. Composition. Bile is a complex ...
  18. [18]
    Physiology, Bile Acids - StatPearls - NCBI Bookshelf
    May 1, 2023 · Before secretion of bile acids, hepatocytes conjugate them with the amino acids taurine or glycine, thereby creating eight different conjugated ...
  19. [19]
    In brief: How does the gallbladder work? - InformedHealth.org - NCBI
    Apr 27, 2021 · This thin-walled, pear-shaped organ is about 7 to 10 centimeters (2.7 to 3.9 inches) long and up to 5 centimeters (2 inches) across at its ...
  20. [20]
    Physiology, Gallbladder - StatPearls - NCBI Bookshelf
    May 1, 2023 · The function of the gallbladder is to store and concentrate bile, which is released into the duodenum during digestion. Bile is an alkaline ...
  21. [21]
    Physiological and molecular biochemical mechanisms of bile ...
    Gallbladder. The bile formed outside the digestive periods enters the gallbladder that performs two important functions: concentration of bile and its storage ...
  22. [22]
    Gallbladder Emptying - an overview | ScienceDirect Topics
    Gallbladder refilling then occurs gradually over the next 60 to 90 minutes. ... The major physiologic stimulant of gallbladder emptying is CCK. This peptide ...
  23. [23]
    Continuous monitoring of nitric oxide release induced by ... - PubMed
    These studies demonstrate that CCK relaxes the choledochal sphincter and this relaxant response is mediated by NO.
  24. [24]
    Apical Sodium Dependent Bile Acid Transporter (ASBT, SLC10A2)
    ASBT is expressed on the apical membrane of enterocytes in the terminal ileum and mediates the reabsorption of bile acids from the ileum.
  25. [25]
    Bile Acid Signaling Pathways from the Enterohepatic Circulation to ...
    Bile acids can be recycled 4–12 times per day between hepatocytes in the liver and enterocytes in the intestine—which is called the enterohepatic circulation ( ...Introduction · Bile Acid Metabolism and the... · Bile Acids and the Blood-Brain...
  26. [26]
    Bile acid transporters - Journal of Lipid Research
    Bile acids ultimately empty from the biliary tract into the small intestine where they are efficiently absorbed in the terminal ileum by the ASBT and OSTα-OSTβ ...Bile Acid Transporters · Ntcp · Regulation Of Bsep...<|separator|>
  27. [27]
    Bile Acid Metabolism in Liver Pathobiology - PMC - PubMed Central
    A constant bile acid pool (3 g) is circulated 4 to 12 times a day. Approximately 95% of bile acids in bile are recirculated back to the liver, and about 5% (0.5 ...
  28. [28]
    Bile acid diarrhoea: pathophysiology, diagnosis and management
    Sep 22, 2020 · The cumulative daily loss of bile acids in faeces daily is 200–400 mg, however, the total bile acid pool is between 3 and 4 g. The ...Missing: grams | Show results with:grams
  29. [29]
    Bile acids: regulation of synthesis: Thematic Review Series
    MECHANISMS OF FXR INHIBITION OF CYP7A1. Bile acid synthesis is feedback inhibited by bile acids returning to the liver via enterohepatic circulation to inhibit ...
  30. [30]
    Fibroblast growth factor 15 functions as an enterohepatic signal to ...
    Here, we demonstrate that fibroblast growth factor 15 (FGF15) signals from intestine to liver to repress the gene encoding cholesterol 7α-hydroxylase (CYP7A1), ...
  31. [31]
    Bile acids activate fibroblast growth factor 19 signaling in human ...
    These results suggest that bile acid-activated FXR is able to induce FGF19 in hepatocytes to inhibit CYP7A1 by an autocrine/paracrine mechanism.
  32. [32]
    Bile Acid Malabsorption Caused by Ileal Resection - JAMA Network
    The increased passage of bile acids into the colon causes diarrhea. In patients with large resections, bile acid malabsorption is severe, and increase in bile ...
  33. [33]
    Lithogenic bile in patients with ileal dysfunction - PMC - NIH
    These studies provide a physicochemical explanation for the clinical observation that patients with ileal dysfunction have an increased incidence of gallstones.
  34. [34]
    Embryology of the Biliary Tract | Digestive Surgery | Karger Publishers
    Jun 10, 2010 · A hepatic diverticulum appears in the ventral wall of the primitive midgut early in the 4th week of intrauterine life in the development of the ...
  35. [35]
    Development of the Bile Ducts: Essentials for the Clinical Hepatologist
    We will briefly review the general aspects of bile duct development and morphogenesis and the main molecular mechanisms involved in bile duct ontogenesis.
  36. [36]
    Molecular Mechanisms of Bile Duct Development - PMC
    One possibility to reconcile these findings is that Sox9 and Notch are part of a cross-regulatory positive feedback loop. Notably, an alternative model of ...Intrahepatic Bile Duct... · Tgfβ Signaling · Wnt/b-Catenin Pathway
  37. [37]
    Aetiology of biliary atresia: what is actually known? - PMC
    Biliary atresia (BA) is a rare disease of unknown etiology and unpredictable outcome, even when there has been timely diagnosis and exemplary surgery.
  38. [38]
    Biliary Atresia - StatPearls - NCBI Bookshelf - NIH
    There is a geographical variance among different varieties of biliary atresia with BASM having a 10% reported incidence in European studies and much less ...Continuing Education Activity · Introduction · Etiology · Treatment / Management
  39. [39]
    Biliary Atresia: Clinical Phenotypes and Aetiological Heterogeneity
    Dec 1, 2021 · The incidence of BA is markedly variable across the world, ranging from about 1:5–10,000 live births in Taiwan [2] and Japan [3] and presumably ...
  40. [40]
    Pathogenesis of Biliary Atresia: Biology to Clinical Phenotypes
    Embryonic biliary atresia​​ About 10% of affected infants have an earlier onset of jaundice, often present at birth and have nonhepatic congenital malformations.
  41. [41]
    Choledochal Cyst - StatPearls - NCBI Bookshelf - NIH
    A choledochal cyst (CC) or biliary cyst is a congenital or acquired anomaly affecting the biliary tree. It involves the dilation of the biliary tree.
  42. [42]
    Choledochal cysts: Part 1 of 3: Classification and pathogenesis - NIH
    Choledochal cysts (CCs) are rare medical conditions with an incidence in the western population of 1 in 100 000–150 000 live births.
  43. [43]
    Metastatic Cholangiocarcinoma following Choledochal Cyst Excision
    The risk of cholangiocarcinoma in patients with an unresected choledochal cyst remains at 20-30%1. Of the five types of choledochal cyst, by far the most common ...Missing: lifetime | Show results with:lifetime<|control11|><|separator|>
  44. [44]
    Alagille Syndrome - GeneReviews® - NCBI Bookshelf
    May 19, 2000 · Offspring of an individual with ALGS have a 50% chance of inheriting the JAG1 or NOTCH2 pathogenic variant. Prenatal testing for pregnancies at ...
  45. [45]
    Alagille syndrome: Genetics and Functional Models - PMC - NIH
    In ALGS, 94–95% of patients have a heterozygous mutation in the Notch ligand, JAG1 (Figure 1A), and 1–2% of patients have a heterozygous mutation in the Notch ...
  46. [46]
    Novel Heterozygous Mutations in JAG1 and NOTCH2 Genes ... - NIH
    ALGS is estimated to occur in 1 in every 70,000–100,000 live births, with the prevalence underestimated due to the highly variable expressivity observed within ...Missing: incidence | Show results with:incidence
  47. [47]
    Developmental abnormalities and liver disease in childhood - PMC
    Absence (agenesis) of a lobe of the liver​​ The anomaly was associated with biliary tract disease in 12 patients, portal hypertension in seven patients, other ...
  48. [48]
    Caroli Disease - StatPearls - NCBI Bookshelf - NIH
    Aug 16, 2024 · Although the incidence of pancreatitis in Caroli disease is low, there have been case reports of patients being diagnosed with Caroli disease ...
  49. [49]
    Gallbladder agenesis with choledochal cyst—a rare association - NIH
    Jan 9, 2013 · Type V has intrahepatic cysts of biliary tree (Caroli's disease) with a 20% incidence.
  50. [50]
    Gallstones (Cholelithiasis) - StatPearls - NCBI Bookshelf - NIH
    Jun 2, 2025 · Gallstones are crystallized deposits forming in the gallbladder or biliary tree, primarily composed of cholesterol, bilirubin, and bile.
  51. [51]
    Epidemiology of Gallbladder Disease: Cholelithiasis and Cancer - NIH
    The majority will not develop symptoms: up to 80% will never experience biliary pain or complications such as acute cholecystitis, cholangitis, or pancreatitis.Missing: pathophysiology | Show results with:pathophysiology
  52. [52]
    Choledocholithiasis - StatPearls - NCBI Bookshelf - NIH
    Acute cholangitis is characterized by fever, jaundice, and abdominal pain, and it results due to infection in the setting of biliary obstruction. The right ...Choledocholithiasis · Treatment / Management · Staging
  53. [53]
    Cholangitis - StatPearls - NCBI Bookshelf - NIH
    Symptoms include fever, chills, malaise, rigors, generalized abdominal pain, jaundice, pruritus, and pale stools. Medical history, including cholelithiasis, ...
  54. [54]
    Definitions, pathophysiology, and epidemiology of acute cholangitis ...
    Acute cholangitis and cholecystitis mostly originate from stones in the bile ducts and gallbladder. Acute cholecystitis also has other causes, such as ischemia; ...
  55. [55]
    Acute cholangitis - an update - PMC - NIH
    Acute cholangitis is bacterial infection of the extra-hepatic biliary system. As it is caused by gallstones blocking the common bile duct in most of the cases, ...Clinical Presentation · Management · Figure 6
  56. [56]
    Cholangiocarcinoma - StatPearls - NCBI Bookshelf - NIH
    May 6, 2024 · Cholangiocarcinoma is a rare but highly aggressive malignancy of the biliary tract. Symptoms may be vague, especially when the neoplasm begins ...
  57. [57]
    Epidemiology and Risk Factors of Cholangiocarcinoma - PMC - NIH
    Cholangiocarcinoma (CCA) is the second most common primary liver cancer, being characterized by its late diagnosis and fatal outcome.
  58. [58]
    Primary Sclerosing Cholangitis - StatPearls - NCBI Bookshelf - NIH
    Primary sclerosing cholangitis (PSC) is a chronic and progressive cholestatic liver disorder of unknown etiology. PSC is characterized by inflammation, fibrosis ...
  59. [59]
    Primary sclerosing cholangitis (PSC) - Symptoms and causes
    Oct 14, 2025 · PSC is rare, affecting up to 1 in 10,000 people. PSC often is linked with inflammatory bowel disease (IBD), especially ulcerative colitis.Missing: epidemiology | Show results with:epidemiology
  60. [60]
    Cancer risk in primary sclerosing cholangitis - NIH
    PSC is associated with a major lifetime risk of gastrointestinal cancers. Compared with the general population, patients with PSC have double the risk of cancer ...Missing: cysts | Show results with:cysts
  61. [61]
    Primary Biliary Cholangitis - StatPearls - NCBI Bookshelf
    Primary biliary cholangitis (PBC), formerly termed primary biliary cirrhosis, is an autoimmune disorder that gradually destroys intrahepatic bile ducts.
  62. [62]
    Primary biliary cholangitis: Epidemiology, prognosis, and treatment
    Jun 2, 2023 · Liver disease progression is inevitable in most untreated individuals, with fibrosis and cirrhosis ensuing as a consequence of the inflammatory ...
  63. [63]
    Acute cholangitis: Diagnosis and management - ScienceDirect
    Highlighting biliary tract dilatation or an obstacle in the biliary tract is a key diagnostic element. Several imagery modalities may be envisioned: abdominal ...
  64. [64]
    Biliary Disease Workup: Laboratory Studies, Imaging Studies, Staging
    May 15, 2025 · A biliary source is inferred when the alkaline phosphatase is associated with an elevated gamma-glutamyl transpeptidase (GGT), 5'-nucleotidase, ...
  65. [65]
    Laboratory Tests of the Liver and Gallbladder - Merck Manuals
    The most useful laboratory tests to screen for liver disorders are serum aminotransferases (the most commonly used liver tests), bilirubin, and alkaline ...
  66. [66]
    Revised estimates of diagnostic test sensitivity and specificity in ...
    Results: Ultrasound has the best unadjusted sensitivity (0.97; 95% confidence interval, 0.95 to 0.99) and specificity (0.95; 95% confidence interval, 0.88 to 1 ...
  67. [67]
    Common bile duct | Radiology Reference Article - Radiopaedia.org
    Sep 18, 2025 · Thus, the oft-quoted normal value of less than 6 mm (measured inner aspect of wall to inner aspect of wall, typically by ultrasound) in adults ...
  68. [68]
    Imaging of Biliary Tract Disease | AJR
    Imaging of biliary disease often requires a multimodality imaging approach, with increasing use of MRCP reducing the requirement for diagnostic ERCP.
  69. [69]
    Accuracy of magnetic resonance cholangiography compared ... - NIH
    In detail, we found MRCP had slightly higher sensitivity and PPV than other reported series and slightly lower accuracy in diagnosing biliary calculi when the ...Mrcp Procedures · Ercp Procedures · Results
  70. [70]
    ERCP (endoscopic retrograde cholangio pancreatography) - Overview
    An ERCP can cause mild inflammation of the pancreas (pancreatitis). This happens to about 5 in every 100 people who have an ERCP. If you have pancreatitis, you ...
  71. [71]
    Optimal hepatobiliary scintigraphy for gallbladder dyskinesia - PMC
    Ten percent of these scans reported a gallbladder ejection fraction (< 35%) that qualified as hypokinesia. Concurrent analysis of CCK-stimulated HIDA scans ...
  72. [72]
    Role of endoscopic ultrasound in gallbladder and biliary system ...
    Jan 18, 2024 · Endoscopic ultrasound (EUS) significantly aids in diagnosing gallbladder abnormalities, including polypoidal lesions and microlithiasis. It ...
  73. [73]
    Primary Biliary Cholangitis - PBC | Choose the Right Test
    May 8, 2025 · Antimitochondrial M2 antibodies (AMAs) are present in the serum of >90% of patients with primary biliary cholangitis (PBC), and antinuclear ...Primary Biliary Cholangitis... · Laboratory Testing · Arup Laboratory Tests
  74. [74]
    Tokyo Guidelines 2018: diagnostic criteria and severity grading of ...
    Oct 15, 2017 · Diagnostic criteria for acute cholangitis ; A-1, Fever, BT >38°C ; A-2, Evidence of inflammatory response, WBC count (×1,000/μL), <4 or >10.Abstract · Introduction · Diagnostic criteria for acute... · Severity grading criteria for...
  75. [75]
    TG13 guidelines for diagnosis and severity grading of acute ...
    Jan 11, 2013 · The diagnostic criteria of the updated Tokyo Guidelines (TG13) have high sensitivity (87.6 %) and high specificity (77.7 %). TG13 has better ...
  76. [76]
    Practice Guidelines - AASLD
    AASLD's practice guidelines provide evidence-based recommendations and outline appropriate methods of treatment and care for clinicians.Primary Biliary Cholangitis · Vascular Liver Disorders · Patient Guidelines
  77. [77]
    Surgical and Nonsurgical Management of Gallstones - AAFP
    May 15, 2014 · Antibiotic prophylaxis is not required in low-risk patients undergoing elective laparoscopic cholecystectomy, but it may reduce the incidence ...<|control11|><|separator|>
  78. [78]
    [PDF] ASGE guideline on the role of endoscopy in the evaluation and ...
    guidelines for the diagnosis and treatment of bile duct stones. Furthermore, they adhere to the Institute of Med- icine standards for guideline creation.
  79. [79]
    American Society for Gastrointestinal Endoscopy guideline on the ...
    This clinical practice guideline from the American Society for Gastrointestinal Endoscopy provides an evidence-based approach for the role of therapeutic EUS ...
  80. [80]
    Endoscopic ultrasound-guided biliary drainage-current status ... - NIH
    Dec 16, 2021 · Endoscopic retrograde cholangiopancreatography (ERCP) is a first-line treatment option for patients with biliary obstruction. The success rate ...Eus-Bd Techniques · Eus-Hgs · Eus-Cds
  81. [81]
    Guidelines for the Clinical Application of Laparoscopic Biliary Tract ...
    Antibiotics are not required in low risk patients undergoing laparoscopic cholecystectomy. (Level I, Grade A). Antibiotics may reduce the incidence of wound ...
  82. [82]
    Kasai Procedure: Surgery To Treat Biliary Atresia - Cleveland Clinic
    Oct 16, 2024 · The Kasai procedure is a surgical treatment for infants with biliary atresia. Your baby's surgeon removes blocked ducts in your baby's liver.
  83. [83]
    A Placebo-Controlled Trial of Obeticholic Acid in Primary Biliary ...
    Aug 18, 2016 · Obeticholic acid administered with ursodiol or as monotherapy for 12 months in patients with primary biliary cholangitis resulted in decreases from baseline in ...
  84. [84]
    Waitlist survival of patients with primary sclerosing cholangitis in the ...
    The ability of the Model for End-Stage Liver Disease (MELD) score to ... Liver Failure / mortality*; Liver Failure / surgery*; Liver Transplantation ...Missing: ERCP | Show results with:ERCP
  85. [85]
    Chapter 19 – Transplant hepatology: A comprehensive update
    Liver transplantation (LT) is the only life-saving therapy in patients with advanced liver disease, cirrhosis or acute liver failure. Although LT is a true ...