The Biliary System PDF

Chapter 10 Gallbladder and the Biliary System Copyright © 2018 Elsevier Inc. All rights reserved.  Anatomy of the Biliary System  The biliary apparatus consists of the right and left hepatic ducts, the common hepatic duct, the common bile duct, the pear-shaped gallbladde...

Chapter 10 Gallbladder and the Biliary System Copyright © 2018 Elsevier Inc. All rights reserved.  Anatomy of the Biliary System  The biliary apparatus consists of the right and left hepatic ducts, the common hepatic duct, the common bile duct, the pear-shaped gallbladder, and the cystic duct. Copyright © 2018 Elsevier Inc. All rights reserved. 2 Anatomy of the Biliary System (Cont.) Copyright © 2018 Elsevier Inc. All rights reserved. 3  Hepatic Ducts  The right and left hepatic ducts emerge from the right lobe of the liver in the porta hepatis and unite to form the common hepatic duct, which then passes caudally and medially.  The hepatic duct runs parallel with the portal vein.  Each hepatic duct is formed by the union of bile canaliculi from the liver lobules. Copyright © 2018 Elsevier Inc. All rights reserved. 4  Hepatic Ducts (Cont.)  The common hepatic duct is approximately 4 mm in diameter and descends within the edge of the lesser omentum.  It is joined by the cystic duct to form the common bile duct.  The common hepatic duct is the bile duct system that drains the liver into the common bile duct. Copyright © 2018 Elsevier Inc. All rights reserved. 5  Common Bile Duct  Normal common bile duct has a diameter of up to 6 mm.  The first part of the duct lies in the right free edge of the lesser omentum.  The second part of the duct is situated posterior to the first part of the duodenum.  The third part lies in a groove on the posterior surface of the head of the pancreas.  It ends by piercing the medial wall of the second part of the duodenum approximately halfway down the duodenal length. Copyright © 2018 Elsevier Inc. All rights reserved. 6  Common Bile Duct (Cont.)  The common bile duct is joined by the main pancreatic duct; together they open through a small ampulla (the ampulla of Vater) into the duodenal wall. Copyright © 2018 Elsevier Inc. All rights reserved. 7 Common Bile Duct (Cont.) Copyright © 2018 Elsevier Inc. All rights reserved. 8  Common Bile Duct (Cont.)  The end parts of both ducts (the common bile duct and the main pancreatic duct) and the ampulla are surrounded by circular muscle fibers known as the sphincter of Oddi.  The proximal portion is lateral to hepatic artery and anterior to portal vein.  The duct moves more posterior after it descends behind the duodenal bulb and enters the pancreas.  The distal duct lies parallel to the anterior wall of the vena cava. Copyright © 2018 Elsevier Inc. All rights reserved. 9  Common Bile Duct (Cont.)  Within the liver parenchyma, the bile ducts follow the same course as the portal venous and hepatic arterial branches.  The hepatic and bile ducts are encased in a common collagenous sheath, forming the portal triad. Copyright © 2018 Elsevier Inc. All rights reserved. 10  Cystic Duct  4 cm long  Connects the neck of the gallbladder with the common hepatic duct to form common bile duct  Somewhat S-shaped  Descends for a variable distance in the right free edge of the lesser omentum Copyright © 2018 Elsevier Inc. All rights reserved. 11  Gallbladder  Pear-shaped sac in the anterior aspect of the right upper quadrant, closely related to the visceral surface of the liver Copyright © 2018 Elsevier Inc. All rights reserved. 12  Gallbladder (Cont.)  Divided into the fundus, body, and neck  The rounded fundus usually projects below the inferior margin of the liver, where it comes into contact with the anterior abdominal wall at the level of the ninth right costal cartilage.  The body generally lies in contact with the visceral surface of the liver and is directed upward, backward, and to the left.  The neck becomes continuous with the cystic duct, which turns into the lesser omentum to join the right side of the common hepatic duct to form the common bile duct. Copyright © 2018 Elsevier Inc. All rights reserved. 13  Gallbladder (Cont.) Transverse view of the RUQ. The cross-section of the abdomen is demonstrated at the level of the second lumbar vertebra. Copyright © 2018 Elsevier Inc. All rights reserved. 14  Gallbladder (Cont.) Transverse view of the RUQ. The cross-section of the abdomen is demonstrated at the level of the third lumbar vertebra. Copyright © 2018 Elsevier Inc. All rights reserved. 15  Gallbladder (Cont.) Sagittal section of the abdomen, 8 cm from the midline. Copyright © 2018 Elsevier Inc. All rights reserved. 16  Gallbladder (Cont.) Sagittal section of the abdomen, 7 cm from the midline. Copyright © 2018 Elsevier Inc. All rights reserved. 17  Gallbladder (Cont.)  Occasionally, the gallbladder lies in an intrahepatic or other anomalous location.  The size and shape of the gallbladder are variable.  The normal gallbladder generally measures 2.5 to 4 cm in diameter and 7 to 10 cm in length.  The walls are less than 3 mm thick.  Dilation of the gallbladder is known as hydrops. Copyright © 2018 Elsevier Inc. All rights reserved. 18  Gallbladder (Cont.)  Anatomic variations The gallbladder may fold back on itself at the neck, forming Hartmann’s pouch. Partial septation Complete septation (double gallbladder) Folding of the fundus (Phrygian cap) Copyright © 2018 Elsevier Inc. All rights reserved. 19 Gallbladder: Anatomic Variants A, Septations; B, Phrygian cap; C, Double gallbladder. Copyright © 2018 Elsevier Inc. All rights reserved. 20  Gallbladder  With a capacity of 50 ml, the gallbladder serves as a reservoir for bile.  The gallbladder can also concentrate the bile.  To aid this process, its mucous membrane contains folds that unite with each other, giving the surface a honeycomb appearance.  Heister valve in the neck of the gallbladder helps prevent a kinking of the duct. Copyright © 2018 Elsevier Inc. All rights reserved. 21  Removal of the Gallbladder  When the gallbladder is removed (cholecystectomy) The sphincter of Oddi loses tonus. Pressure within the common bile duct drops to that of intraabdominal pressure. Bile is no longer retained in the bile ducts; it is free to flow into the duodenum during fasting and digestive phases. The extrahepatic bile ducts dilate, usually less than 1 cm. Copyright © 2018 Elsevier Inc. All rights reserved. 22 Removal of the Gallbladder (Cont.)  Secretion is largely caused by a bile salt– dependent mechanism, and ductal flow is controlled by secretion.  Bile is the principal medium for excretion of bilirubin and cholesterol.  The bile salts from the intestine stimulate the liver to make more bile.  Bile salts activate intestinal and pancreatic enzymes. Copyright © 2018 Elsevier Inc. All rights reserved. 23  Sonographic Evaluation of the Biliary System (Cont.) The main lobar fissure (MLF) is seen as an echogenic linear echo within the liver (L) connecting the right portal vein (PV) to the neck of the gallbladder (GB). Copyright © 2018 Elsevier Inc. All rights reserved. 24  Sonographic Evaluation of the Biliary System (Cont.) Transverse (A) and longitudinal (B) scans of the distended gallbladder. Copyright © 2018 Elsevier Inc. All rights reserved. 25  Sonographic Evaluation of the Biliary System (Cont.) Distension (hydrops) of the gallbladder. Copyright © 2018 Elsevier Inc. All rights reserved. 26  Sonographic Characteristics of the Normal Gallbladder  Size: 10 mm is dilated. Copyright © 2018 Elsevier Inc. All rights reserved. 97  Dilated Biliary Ducts (Cont.) Sagittal scan of a prominent common bile duct as it runs anterior to the portal vein and posterior to the head of the pancreas. Copyright © 2018 Elsevier Inc. All rights reserved. 98  Biliary Obstruction  Most common cause is the presence of a tumor or thrombus within the ductal system.  Process may be found in the extrahepatic or intrahepatic ductal pathway.  Obstruction of biliary ductal system is diagnosed by ultrasound when the sonographer finds the presence of ductal dilation. This finding is called “too many tubes” or “shotgun” sign when intrahepatic ducts are dilated. Copyright © 2018 Elsevier Inc. All rights reserved. 99  Biliary Obstruction (Cont.)  Bile ducts expand centrifugally from the point of obstruction.  Therefore extrahepatic dilation occurs before intrahepatic dilation.  In patients with obstructive jaundice, isolated dilation of the extrahepatic duct may be present. Copyright © 2018 Elsevier Inc. All rights reserved. 100  Biliary Obstruction (Cont.)  Fibrosed or infiltrative disease of the liver may prevent intrahepatic dilation because of a lack of compliance of the hepatic parenchyma.  Clinically, the elevation of cholestatic liver parameters may present as jaundice.  Painful jaundice is seen with acute obstruction or infection that may invade the biliary tree. Copyright © 2018 Elsevier Inc. All rights reserved. 101  Extrahepatic Biliary Obstruction  Three primary areas for biliary obstruction: Intrapancreatic Suprapancreatic Porta hepatic Copyright © 2018 Elsevier Inc. All rights reserved. 102 Extrahepatic Biliary Obstruction (Cont.) Levels of obstruction. Porta hepatic. Copyright © 2018 Elsevier Inc. All rights reserved. 103 Extrahepatic Biliary Obstruction (Cont.) Levels of obstruction. Intrahepatic and suprapancreatic. Copyright © 2018 Elsevier Inc. All rights reserved. 104  Intrapancreatic Obstruction  Three conditions cause the majority of biliary obstruction at the level of the distal duct and cause the extrahepatic duct to be entirely dilated: Pancreatic carcinoma Choledocholithiasis Chronic pancreatitis with stricture formation Copyright © 2018 Elsevier Inc. All rights reserved. 105 Intrapancreatic Obstruction (Cont.) Copyright © 2018 Elsevier Inc. All rights reserved. 106  Suprapancreatic Obstruction  Originates between the pancreas and the porta hepatis  The head of the pancreas, the intrapancreatic duct, and pancreatic duct are normal with ultrasound.  The most common cause for this obstruction is malignancy or adenopathy at this level. Copyright © 2018 Elsevier Inc. All rights reserved. 107  Porta Hepatic Obstruction  This area of obstruction is usually the result of a neoplasm.  In patients with obstruction at the level of the porta hepatis, ultrasound will show intrahepatic ductal dilation and a normal common duct.  Hydrops of the gallbladder may be present. Copyright © 2018 Elsevier Inc. All rights reserved. 108  Other Causes of Obstruction  Cholangiocarcinoma Rare malignancy that originates within the larger bile ducts (usually the common duct or common hepatic duct) Copyright © 2018 Elsevier Inc. All rights reserved. 109  Other Causes of Obstruction (Cont.)  Klatskin tumor is a specific type of cholangiocarcinoma that can occur at the bifurcation of the common hepatic duct, with involvement of both the central left and right ducts.  The most suggestive sonographic feature that indicates cholangiocarcinoma is isolated intrahepatic duct dilation.  Although the obstructing mass may not be imaged, a nonunion of the right and left ducts is characteristic for a Klatskin tumor. Copyright © 2018 Elsevier Inc. All rights reserved. 110  Other Causes of Obstruction (Cont.)  Mirizzi syndrome is uncommon cause for extrahepatic biliary obstruction as a result of an impacted stone in the cystic duct, which creates extrinsic mechanical compression of the common hepatic duct.  Patient presents with painful jaundice.  Stones may penetrate into the common hepatic duct or the gut, resulting in a cholecystobiliary or cholecystenteric fistula.  Cystic duct inserts unusually low into the common hepatic duct; thus the two ducts have parallel alignment, which allows for the development of this syndrome.  On ultrasound, an intrahepatic ductal dilation is seen with a normal-size common duct and a large stone in the neck of the gallbladder or cystic duct. Copyright © 2018 Elsevier Inc. All rights reserved. 111 Mirizzi Syndrome Copyright © 2018 Elsevier Inc. All rights reserved. 112  Other Causes of Obstruction  Tumors arising from the common bile duct and ampullar carcinoma have the same ultrasonic features as pancreatic tumors.  A specific pattern exists when the ampulloma bulges inside a dilated common bile duct.  Cancer of the biliary convergence or of the hepatic duct usually infiltrates the ductal wall without bulging outside.  Imaging these tumors may be difficult; the diagnosis is indirect and based on biliary dilation above the tumor. Copyright © 2018 Elsevier Inc. All rights reserved. 113  Other Causes of Obstruction (Cont.) Inflammation of the pancreas may cause the common duct to dilate. This patient has acute pancreatitis (P) and dilation of the common duct (crossbars). A, Aorta; IVC, inferior vena cava. Copyright © 2018 Elsevier Inc. All rights reserved. 114  Other Causes of Obstruction (Cont.) Carcinoma of the head of the pancreas with obstruction of the common bile duct (CBD) is demonstrated. Copyright © 2018 Elsevier Inc. All rights reserved. 115  Other Causes of Obstruction (Cont.) Dilated intrahepatic ducts secondary to a mass in the area of the porta hepatis. Copyright © 2018 Elsevier Inc. All rights reserved. 116  Distinguishing Bile Ducts from Intrahepatic Structures  Alteration in the anatomic pattern: Is adjacent to the main (right) portal vein segment and the bifurcation. This appearance is more pronounced in individuals who display greater degrees of dilation of the intrahepatic bile ducts.  Irregular walls of dilated bile ducts: As the intrahepatic biliary system dilates, the course and caliber of ducts become increasingly tortuous and irregular.  Stellate confluence of dilated ducts: This appearance is noted at the points where the ducts converge. Dilated ducts look similar to the spokes of a wheel. Copyright © 2018 Elsevier Inc. All rights reserved. 117  Distinguishing Bile Ducts from Intrahepatic Structures (Cont.)  Acoustic enhancement by dilated bile ducts: Both portal veins and ducts are surrounded by high-amplitude reflections.  Peripheral duct dilation: Visualizing hepatic ducts in the liver periphery is normally unusual, whereas dilated bile ducts may be observed. Copyright © 2018 Elsevier Inc. All rights reserved. 118  Choledocholithiasis  Primary choledocholithiasis is the de novo formation of calcium stones in the bile duct. These stones may result from disease, causing strictures or dilation of the bile ducts, leading to stasis. Sclerosing cholangitis, Caroli’s disease, parasitic infections, chronic hemolytic diseases, prior biliary surgery  Secondary choledocholithiasis denotes the majority of stones in the common bile duct have migrated from the gallbladder. Common duct stones are usually associated with calculous cholecystitis. Copyright © 2018 Elsevier Inc. All rights reserved. 119  Choledocholithiasis (Cont.) A, Transverse plane demonstrates gallstones (arrow). GB, gallbladder. Copyright © 2018 Elsevier Inc. All rights reserved. 120  Hemobilia  Main cause of hemobilia is biliary trauma secondary to percutaneous biliary procedures or liver biopsies.  Other causes include: Cholangitis, cholecystitis, vascular malformations, abdominal trauma, and malignancies  Clinical findings Pain Bleeding Jaundice Copyright © 2018 Elsevier Inc. All rights reserved. 121  Hemobilia (Cont.)  Sonographic appearance of blood in the biliary tree Depends on the length of time the blood has been present Acute hemorrhage will appear as fluid with low-level internal echoes. Look for blood clots that may move in the duct with extension into the gallbladder. Copyright © 2018 Elsevier Inc. All rights reserved. 122  Pneumobilia  Pneumobilia is air within the biliary tree secondary to biliary intervention, biliary-enteric anastomoses, or common bile duct stents.  In the patient with an acute abdomen, pneumobilia may be caused by the following: Emphysematous cholecystitis Inflammation from an impacted stone in the common bile duct Prolonged acute cholecystitis, which may lead to erosion of the bowel Copyright © 2018 Elsevier Inc. All rights reserved. 123  Pneumobilia (Cont.)  Sonographic findings The air in the bile ducts appears as bright, echogenic linear structures that follow the portal triads. The posterior dirty shadow and reverberation artifact are seen. Movement of tiny air bubbles with a change in the patient’s position should be noted. Copyright © 2018 Elsevier Inc. All rights reserved. 124  Cholangitis  Cholangitis is an inflammation of the bile ducts. Copyright © 2018 Elsevier Inc. All rights reserved. 125  Cholangitis (Cont.)  Cholangitis May be identified as Oriental sclerosing cholangitis. Other forms include AIDS cholangitis and acute obstructive suppurative cholangitis. Patients have malaise and fever, followed by sweating and shivering, right upper quadrant pain, and jaundice. In severe cases, patient is lethargic, prostrate, and in shock. Laboratory values show leukocytosis and an elevation of serum alkaline phosphatase and bilirubin. Copyright © 2018 Elsevier Inc. All rights reserved. 126  Ascariasis  Disease is caused by the parasitic roundworm, Ascaris lumbricoides, which uses a fecal-oral route of transmission.  The worms may be 20 to 30 cm long and 6 cm in diameter.  The worms grow in the small bowel before entering the biliary tree through the ampulla of Vater.  Cause acute biliary obstruction  Clinically, the patient may be asymptomatic or have biliary colic, pancreatitis, or biliary symptoms. Copyright © 2018 Elsevier Inc. All rights reserved. 127 Ascariasis (Cont.) Copyright © 2018 Elsevier Inc. All rights reserved. 128  Intrahepatic Biliary Neoplasms  Intrahepatic biliary tumors are rare and primarily limited to cystadenoma and cystadenocarcinoma.  Found more frequently in middle-aged women whose clinical presentation includes abdominal pain or mass or jaundice or both (if the mass is near the porta hepatis).  Sonographic appearance: Cystic mass with multiple septa and papillary excrescences Mass may show variations in this pattern and appear as unilocular, calcified, or multiple. Lesion may be associated with dilation of the intrahepatic ducts.  Differential diagnoses include a hemorrhagic cyst or infection, echinococcal cyst, abscess, or cystic metastasis. Copyright © 2018 Elsevier Inc. All rights reserved. 129  Cholangiocarcinoma  Intrahepatic cholangiocarcinoma Is the second most common primary malignancy of the liver Incidence of this tumor has risen, secondary to increasing number of patients with liver cirrhosis and hepatitis C infection. These tumors are often unresectable with a poor prognosis. Copyright © 2018 Elsevier Inc. All rights reserved. 130 Cholangiocarcinoma (Cont.) Copyright © 2018 Elsevier Inc. All rights reserved. 131  Intrahepatic Cholangiocarcinoma  Sonographic findings Large hepatic mass Hypoechoic to hyperechoic Heterogeneous texture or hypovascular solid mass Biliary ductal dilation associated with these obstructive masses in one third of cases Copyright © 2018 Elsevier Inc. All rights reserved. 132 Intrahepatic Cholangiocarcinoma (Cont.) Copyright © 2018 Elsevier Inc. All rights reserved. 133  Hilar Cholangiocarcinoma  Includes jaundice, pruritus, and elevated cholestatic liver parameters.  Begins in the right or left bile duct and then extends into the proximal duct and distally into the common hepatic duct and contralateral bile ducts.  Tumor may extend outside of the ducts to involve the adjacent portal vein and arteries.  Chronic obstruction leads to atrophy of the involved lobe.  Majority of patients die within 1 year of diagnosis. Copyright © 2018 Elsevier Inc. All rights reserved. 134 Hilar Cholangiocarcinoma (Cont.) Copyright © 2018 Elsevier Inc. All rights reserved. 135  Distal Cholangiocarcinoma  Is difficult to distinguish from hilar cholangiocarcinoma; progressive jaundice is seen in the majority of patients.  Tumor mass may be sclerosing or polypoid.  Tumor spread in the superior ductal system and extrahepatic area should be carefully evaluated.  May extend into the adjacent lymph nodes.  Sonographic findings Sclerosing tumor is nodular with focal irregular ductal constriction and wall thickening. Has a hypoechoic and hypovascular appearance with poorly defined margins Copyright © 2018 Elsevier Inc. All rights reserved. 136 Distal Cholangiocarcinoma (Cont.) Copyright © 2018 Elsevier Inc. All rights reserved. 137  Metastases to the Biliary Tree  Most common tumor sites that can spread to the biliary system are from the breast, colon, or melanoma.  Metastases can affect the intrahepatic and extrahepatic ductal systems.  On sonography, the appearance of metastases is similar to that of cholangiocarcinoma. Copyright © 2018 Elsevier Inc. All rights reserved. 138 Metastases to the Biliary Tree (Cont.) Copyright © 2018 Elsevier Inc. All rights reserved. 139