Gross Anatomy
Pear-shaped sac (~7-10 cm, 30-50 mL capacity) on inferior surface of right hepatic lobe.
Parts
- Fundus — blind-ended tip; palpable in cholecystitis
- Body — main portion on hepatic surface
- Neck — joins cystic duct; spiral valve of Heister
- Hartmann's pouch — outpouching at neck; stones can lodge here
Blood Supply
- Cystic artery — branch of right hepatic artery; runs through Calot's triangle
- Calot's triangle — bordered by liver, CHD, cystic duct; key surgical landmark
Murphy's sign: inspiratory arrest with RUQ palpation — classic for acute cholecystitis.
Microscopic Anatomy
Wall Layers
- Mucosa — simple columnar epithelium; highly folded (rugae); NO muscularis mucosae or submucosa
- Muscularis — smooth muscle; contracts with CCK
- Serosa — covers free surface; absent on hepatic surface (adventitia instead)
Rokitansky-Aschoff sinuses — mucosa invaginates through the muscularis wall. Prominent in chronic cholecystitis. "Strawberry gallbladder" = cholesterol deposits on mucosa.
Biliary Tract
| Structure | Description | Clinical Note |
|---|---|---|
| R+L hepatic ducts | Drain liver lobes | Join at porta hepatis |
| Common hepatic duct | R+L join | Above cystic duct |
| Cystic duct | GB neck to CHD | Spiral valve of Heister |
| Common bile duct | CHD + cystic duct | Passes behind duodenum |
| Ampulla of Vater | CBD + pancreatic duct | Opens into D2 of duodenum |
| Sphincter of Oddi | Smooth muscle valve | Regulates flow; relaxes with CCK |
Charcot's triad (RUQ pain + fever + jaundice) = cholangitis. Reynolds' pentad adds AMS + septic shock. Choledocholithiasis → ↑direct bilirubin, ↑ALP, ↑GGT.
Bile
Composition
- Bile salts — cholate, chenodeoxycholate; conjugated with glycine/taurine; emulsify fats
- Phospholipids (lecithin) — solubilize cholesterol
- Cholesterol — must stay in solution via bile salt/lecithin micelles
- Conjugated bilirubin — yellow-green color
GB concentrates bile 5-10x by absorbing Na+, Cl-, and water. CCK (I-cells of duodenum) → GB contraction + sphincter of Oddi relaxation.
Gallstone types: Cholesterol (80%) — radiolucent; 5 F's: Female, Fat, Forty, Fertile, Fair. Pigment — black (hemolysis/cirrhosis) vs brown (infection/stasis).
5 F's for gallstones: Female, Fat, Forty, Fertile, Fair. Also: OCPs, rapid weight loss, Crohn disease (impaired bile salt reabsorption).
Embryology
GB and extrahepatic bile ducts develop from the hepatic diverticulum (pars cystica, caudal portion) of foregut endoderm at ~4 weeks.
- Pars cystica → gallbladder + cystic duct
- Failure of recanalization → biliary atresia
Biliary atresia: progressive jaundice after 2 weeks, acholic stools, ↑conjugated bilirubin. Kasai portoenterostomy before 60 days is essential; untreated → cirrhosis by age 2.
Clinical Pearls
| Condition | Mechanism | Key Features |
|---|---|---|
| Biliary colic | Transient cystic duct obstruction | Episodic RUQ pain after fatty meals; no fever |
| Acute cholecystitis | Sustained obstruction + inflammation | Fever, Murphy's sign, ↑WBC |
| Choledocholithiasis | Stone in CBD | Obstructive jaundice, ↑ALP, ↑GGT |
| Cholangitis | Biliary obstruction + infection | Charcot's triad; Reynolds' pentad if severe |
| PSC | Autoimmune; UC-associated | p-ANCA; beaded ducts on MRCP; ↑ALP; cholangiocarcinoma risk |
Porcelain gallbladder = calcification of GB wall from chronic cholecystitis. Associated with increased GB carcinoma risk (debated). Visible on plain X-ray or CT as calcified outline.