Gallbladder

The Gallbladder and the Biliary System

Overview of the Biliary System

• Components:

  • Right and left hepatic ducts

  • Common hepatic duct

  • Common bile duct (CBD)

  • Gallbladder

  • Cystic duct

Functions of the Biliary System

• Waste Product Drainage:

  • Drains waste from liver into duodenum

• Digestion Support:

  • Controlled release of bile aids in digestion

• Waste Removal:

  • Carries away waste products

• Fat Breakdown:

  • Breaks down fats during digestion

Bile Function

• Digestion and Absorption:

  • Aids in digestion of lipids and lipid-soluble vitamins

• Waste Elimination:

  • Secretes waste into bile for elimination in feces

• Acid Neutralization:

  • Neutralizes gastric acid in the small intestine

Bile Formation and Composition

• Production:

  • Liver produces bile continuously, excreting into bile canaliculi

• Volume:

  • Produces 500-1000 mL of bile daily

• Composition:

  • Mainly composed of water, electrolytes, bile salts, lipids, and bile pigments

Biliary Ducts

• Classification:

  • Intrahepatic: All ducts within the liver

  • Extrahepatic: Common bile duct, cystic duct, part of common hepatic duct

Hepatic Ducts

• Left and Right Ducts:

  • Emerge from the right lobe of the liver at Porta Hepatis

  • Merge to form common hepatic duct

Common Bile Duct

• Dimensions:

  • Length: 7-11 cm

  • Thickness: 7-8 mm

• Anatomy:

  • Opens into Ampulla of Vater (three segments)

Cystic Duct

• Length:

  • 4 cm

• Function:

  • Connects gallbladder neck with common hepatic duct to form the common bile duct

Valves of Heister

• Description:

  • Folds of mucous membrane in upper cystic duct

  • Arranged spirally to prevent duct kinking

Gallbladder Anatomy

• Location:

  • Posterior to right lobe of liver in gallbladder fossa

  • Considered an intraperitoneal organ

• Segments:

  • Fundus (superior)

  • Body (middle)

  • Neck (inferior)

Gallbladder Functions

• Bile Functions:

  • Concentration of bile

  • Storage and release of bile (500-1000 mL daily)

• Response to Meals:

  • Release of bile triggered by food intake

Fasting and Postprandial State

• Fasting State:

  • Gallbladder fills from neural and hormonal stimuli

• Postprandial State:

  • Contracts and empties with fat entrance in duodenum

  • Cholecystokinin (CCK) release promotes contraction and relaxes ampullary sphincter

Blood Supply and Drainage

• Arterial Supply:

  • From the cystic artery (branch of right hepatic artery)

• Venous Drainage:

  • Small veins into liver or cystic vein to portal vein

Anatomic Variations

• Junctional Fold:

  • Common variant between neck and body

• Hartmann’s Pouch:

  • Gallbladder folds back at neck, forming a pouch

• Phrygian Cap:

  • Folding of fundus of the gallbladder

• Complete/Partial Septated Gallbladder

Transportation of Bile

• Bile Flow Sequence:

  • Liver → right and left hepatic ducts → common hepatic duct → joins cystic duct → common bile duct → duodenum upon meal ingestion

Bile Concentration and Release

• Liver secretes bile (~1L/day)

• Gallbladder fills, concentrates bile, and releases it in response to food

Indications for Gallbladder Ultrasound

• Abdominal pain with food ingestion

• Colicky right upper quadrant pain

• Jaundice or atypical right-sided pain

• Abnormal liver function tests

Gallbladder Scanning Techniques

• Use of 5 MHz or higher transducer

• Patient should fast for 8-12 hours

• Position: Supine and left lateral decubitus for object exclusion

Sonographic Appearance

• Postprandial:

  • Contraction and diffuse wall thickening of gallbladder

• Normal Measurements:

  • Diameter: 2.5 to 4 cm; Length: 7 to 10 cm; Wall thickness: ≤ 3 mm

Biliary System Measurement

• Normal gallbladder dimensions and upper limits for common bile duct (1-6 mm, 10 mm in elderly)