Calot’s triangle (cystohepatic triangle) is a small anatomical space in the abdomen.
It is located at the porta hepatis of the liver – where the hepatic ducts and neurovascular structures enter/exit the liver.
In this article, we shall look at the borders, contents and clinical relevance of Calot’s triangle.
Calot’s triangle is orientated so that its apex is directed at the liver. The borders are as follows:
- Medial – common hepatic duct.
- Inferior – cystic duct.
- Superior – inferior surface of the liver.
The above differ 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 (the cystic artery has considerable variation in its anatomical course and origin).
The contents of the Calot’s triangle include:
- 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.
If Calot’s triangle cannot be delineated (such as in cases of severe inflammation), the surgeon may elect to perform a subtotal cholecystectomy, or convert to open surgery.