Calot's Triangle

Mnemonic

“Cystic, common, liver”, the three boundaries of the hepatobiliary triangle:

• Cystic duct, laterally
• Common hepatic duct, medially
• Inferior border of the liver, superiorly

The original description used the cystic artery as the upper border; the surgical version uses the liver edge.

Its contents are the cystic artery, usually from the right hepatic artery, a lymph node (Lund’s node) and areolar tissue.

The critical view of safety in laparoscopic cholecystectomy requires the triangle to be cleared so that only two structures enter the gallbladder, the cystic duct and cystic artery, before either is clipped. Failing to do so is the commonest route to bile duct injury, particularly where the right hepatic artery runs a caterpillar hump course close to the duct.

Expansion

Boundaries:

• Medially - the common hepatic duct
• Laterally (inferiorly) - the cystic duct
• Superiorly - the inferior surface of the liver (Calot’s original description used the cystic artery)

Contents:

• Cystic artery, usually from the right hepatic artery
• Right hepatic artery, often crossing the triangle
• Lymph node of Lund (Calot’s node)

This is the single most important area in laparoscopic cholecystectomy. Misidentifying the common bile duct as the cystic duct is the classic mechanism of bile duct injury, and an aberrant right hepatic artery running close to the cystic duct is a common variant.

Modern practice requires demonstrating the critical view of safety: the triangle cleared of fat and fibrous tissue, the lower third of the gallbladder separated from the liver bed, and exactly two structures seen entering the gallbladder.