Calot's Triangle

Calot's Triangle: Anatomy, Contents and Clinical Relevance

Calot's triangle (cystohepatic triangle) is an anatomical space in the abdomen located at the porta hepatis of the liver, where hepatic ducts and neurovascular structures enter and exit the liver. It is an inverted pyramid-shape and bordered by the cystic duct, common hepatic duct and the right hepatic artery. The contents of Calot's triangle are mainly the cystic artery, lymph node of Lund and surrounding lymphatics.

Borders of Calot's Triangle

Calot's triangle is orientated so that its apex is directed at the liver, with the following borders:

• Medial – common hepatic duct.
• Inferior – cystic duct.
• Superior – inferior surface of the liver.

This differs from the original description of Calot's triangle in 1891 – where the cystic artery is given as the superior border of the triangle. The modern definition gives a more consistent border, as the cystic artery has considerable variation in its anatomical course and origin.

Contents of Calot's Triangle

• Right hepatic artery – formed by the bifurcation of the proper hepatic artery into right and left branches.
• Cystic artery – typically arises from the right hepatic artery and traverses the triangle to supply the gall bladder.
• Lymph node of Lund – the first lymph node of the gallbladder.

Clinical Relevance: Calot's Triangle in Laparoscopic Cholecystectomy

The triangle of Calot is of clinical importance during laparoscopic cholecystectomy (removal of the gall bladder). In this procedure, the triangle is carefully dissected by the surgeon, and its contents and borders identified. This allows the surgeon to take into account any anatomical variation and permits safe ligation and division of the cystic duct and cystic artery.

Of particular importance is the right hepatic artery – this must be identified by the surgeon prior to ligation of the cystic artery. It is also important to recognize Calot’s triangle since it provides the surgeon a safe approach to laparoscopic cholecystectomy.

Anatomical variations can occasionally occur in the Calot’s triangle. For example, the cystic artery arising from the right hepatic artery or the bile duct arising from the gallbladder. This situation requires ligation and division of the cystic artery and bile duct respecting anatomical landmarks. In some clinical cases, subtotal cholecystectomy may be used to avoid injuries to the bile duct and cystic artery.

In conclusion, Calot's triangle is an anatomical space in the abdomen located at the porta hepatis of the liver. It is important to recognize anatomic variations, contents and borders of the triangle as it is a common area in laparoscopic cholecystectomy.