Gallbladder and Billiary System - Ch: 6
Transducer Selection for GB
- 2.5 - 5 MHz curvilinear transducer is utilized for most patients
What is another name for Hepatopancreatic ampulla?
- Ampulla of Vater
Bile salts (Bile acids)
- Are the actual components which help break down and absorb fats during the digesting process
Bile is a greenish-yellow fluid consisting of:
- Bile Salts - Bilirubin - Cholesterol - Water - Electrolytes - Phospholipids
How does Bile Salts travel?
- Bile salts are not excreted with stool - Approximately 95% of bile salts are reabsorbed in the ilium (last section of the small intestine) and returned to the liver via the portal venous system
GB - Blood Supply
- Blood is supplied to the gallbladder from the cystic artery, which branches off of the proper hepatic artery OR right hepatic artery
What should be done to "prove" you are imaging and measuring the Bile duct and not the hepatic artery?
- Color Doppler should be utilized
The Right and Left Hepatic Duct unite at approximately the LEVEL OF PORTA HEPATIS and together they form the ______________. ________________ __________ (_ _ _)?
- Common Hepatic Duct (CHD)
Phrygian Cap
- Congenital GB Variant - A fold between the fundus and body of the GB
Junctional Fold
- Congenital GB Variant - Fold occurring anywhere along the body and/or neck of the GB - may be singular or multiple
Hartmann Pouch
- Congenital GB Variant - Out-pouching of the GB neck. - COMMON LOCATION FOR STONES TO COLLECT
What part of the biliary system does BILE FLOW IN 2 DIRETIONS?
- Cystic Duct • IN through the cystic duct from the CHD for bile storage in the GB • OUT through the cystic duct and down the CBD to aid in digestion
As a general rule we add 1mm per ____________ starting at 60
- Decade
The biliary system plays a role in the __________________ process.
- Digestive
Bile Transport - FASTING
- During a fasting state, bile is forced into the cystic duct into the GB by an increase in pressure and resistance within the CBD. - This increase in resistance is due to the Sphincter of Oddi being closed, not allowing bile to flow into the duodenum
What is the function of the hepatopancreatic ampulla?
- Empties its contents through a small opening in the duodenum referred to as the MAJOR PAPILLA
PERIMUSCULAR layer of the GB
- Fibrous connective tissue layer that surrounds the muscularis
Gallbladder Is divided into three sections:
- Fundus - Body - Neck
Total Duplication
- GB Variant - Two gallbladders and two cystic ducts
Subtotal Division
- GB Variant - Two gallbladders attached to one cystic duct
Interposition of the Gallbladder
- GB Variant • Failure of formation of the CHD and Cystic Duct • Right and Left Hepatic ducts drain separately (or together) directly in the GB • GB drains directly into the CBD • Rare finding • Cause is unknown • May cause intermittent JAUNDICE
WHAT CONTINUALLY PRODUCES BILE?
- Hepatic parenchymal cells (hepatocytes)
The CBD and the Main Pancreatic Duct form the ____________________ _____________ ?
- Hepatopancreatic ampulla (AKA ampulla of Vater)
Patient Positioning for GB
- Initially supine Position - The patient should be turned into the Left Lateral Decubitus (LLD position) - Alternative positions include: • Right Anterior Oblique - for patients unable to turn completely onto their left side • Sitting and/or Standing positions can also be utilized
How is the BCD measured?
- Inner wall to inner wall
MUCOSA
- Innermost layer where RUGAE IS FOUND
SUMMARY OF BILIARY SYSTEM
- Intrahepatic Bile Ducts: • Travel in close proximity to portal vein and hepatic artery branches • Join to form right and left hepatic ducts • Right and left hepatic ducts unite to form common hepatic duct at porta hepatis - Cystic Duct: • Arises from neck of GB • Contains spiral valves of Heister • Joins common hepatic duct to form common bile duct Common Bile Duct: • Joins main pancreatic duct to form hepatopancreatic ampulla (ampulla of Vater)
Gallbladder
- Intraperitoneal - Located posterior to the right lobe of the liver - Situated in the Gallbladder Fossa of the liver - Pear shaped, but variations can be ovoid, round or hourglass - It is an expandable sac - Function is to store bile
Bilirubin
- Is a yellowish waste product that is produced during the normal breakdown of red blood cells (RBC's - which have a lifespan of ~120 days)
Cystic Duct
- Joins the common hepatic duct (CHD) to from the CBD - Cystic Duct + CHD = CBD
MUSCULARIS layer of the GB
- Layer of smooth muscle that helps the GB to contract to push bile out
Sonographic IMAGES of a normal Gallbladder with measurements
- Length: Approx 8 cm - Width (A.P): 4-5 cm - Wall Thickness: 3mm or Less
What is a Landmark for the GB?
- Main Lobar Fissure
The biliary system consists of organs and ducts that are involved in the ___________________ and __________________________ of bile.
- Production and transportation
Gallbladder FUNDUS
- Rounded, blind ended section of the GB - Most dependent portion of the GB - Fundus usually projects below the inferior margin of the right hepatic lobe...but location of fundus can vary as GB is slightly mobile • Because it is the most dependent portion, the fundus is a COMMON LOCATION FOR GALLSTONES TO COLLECT
The Common Hepatic Duct (CHD)
- Runs parallel with the main portal vein - Travels caudally and medially in the body - Joined by the Cystic Duct to form the Common Bile Duct (CBD)
Gallbladder NECK
- Section where the GB begins to taper (narrow) - Connects GB to biliary tree via the cystic duct - COMMON PLACE FOR GMALL GALLSTONES TO GET STUCK
Rugae
- Series of ridges produced by folding of the wall of an expandable organ or structure. - Allows for expansion
Gallbladder Wall Layers
- Serosa - Perimuscular - Muscularis - Mucosa
Physiology of the Biliary System - GB
- The gallbladder stores and concentrates bile - GB can store 30 to 50 ml of bile - Responds to the hormone cholecystokinin (CCK)
Hepatic Ducts
- The network of tiny intrahepatic ductules merge forming larger and larger ducts as they travel to exit the liver. - These merging ducts eventually form the: • Right Hepatic Duct • Left Hepatic Duct
What is the Sonographic appearance of the GB
- Thin echogenic walls - An anechoic lumen - Some posterior enhancement
Common Bile Duct (CBD)
- Transports bile from the gallbladder to the duodenum - Travels caudally and medially towards the pancreas. - The distal portion of the CBD lies in a groove on the posterior surface of the head of the pancreas where it joins the Main Pancreatic Duct
How does bilirubin travel?
- Travels in bile from the liver to the gastrointestinal system - Excreted in stool
GB Venous Drainage
- Venous drainage is via the cystic vein which drains into the right branch of the portal vein
Bile Transportation - NON-FASTING
- When food is ingested, the hormone CHOLECYSTOKININ (CCK) is released by the duodenum. - Cholecystokinin signals the GB to contract, and the Sphincter of Oddi to open. - Bile flows out of the GB, through the cystic duct and into the CBD - The CBD joins with the Main Pancreatic Duct at the level of the head of the pancreas. - Bile and pancreatic juices drain into the duodenum where they mix with partially digested food and liquid from the stomach referred to as chyme. - The process of digestion continues from this point.
Gallbladder BODY
Central portion located between the fundus and neck
Patient History for GB
Prior to scanning - it is important to obtain patient history: • Any prior scans • Lab Values • Surgeries • Symptoms: - Pain - Frequency - Duration - Location
The MAJOR PAPILLA is controlled by a small group of muscles referred to as the ____________ __ ________.
SPHINCTER OF ODDI
SEROSA layer of the GB
outermost smooth membrane of the GB
Normal measurement of the CBD is between __ - __mm?
• 1 - 6 mm - Calipers are placed from inner wall to inner wall
CBD measurement for patients older than 60 or are s/p cholecystectomy can be up to ____ mm and still be considered as normal?
• 10mm
Ducts can vary in: (3)
• Course (straight, curved, angled) • Length • Site of anastomosis
What is the FUNCTION of the BILE DUCTS in the Biliary System?
• Intrahepatic & Extrahepatic Ducts that transport bile
Gallbladder Normal Measurements for Distended GB
• Length: 8cm • Width: 4 - 5 cm • AP: 4 - 5 cm • Wall Thickness: 3mm or less
What are the functioning Structures of the Biliary System? (4)
• Liver • Bile Ducts • Gallbladder • Pancreas
Recall that the intrahepatic ductal system begins at a microscopic level, originating in the liver _________?
• Lobule
Spiral Valves of Heister
• Part of the cystic duct that contains tiny projections referred to as Spiral Valves of Heister • Serve to keep the lumen of the cystic duct open.
What is the FUNCTION of the LIVER in the Biliary System?
• Produces Bile
What is the FUNCTION of the PANCREAS in the Biliary System?
• Produces digestive enzymes
What is the FUNCTION of the GALLBLADDER in the Biliary System?
• Stores Bile
What are the TWO PRIMARY JOBS that BILE HAS?
• To carry away waste from the liver (bilirubin) • To break down fats during digestion (occurs via bile salts)
