Calot’s Triangle: Definition, Anatomy, Location, Clinical Significance and Importance

The cystic artery is located inside the cystohepatic triangle, which is used to locate it during a laparoscopic cholecystectomy .

The hepatobiliary triangle (or cystohepatic triangle) is an anatomical space limited by the cystic duct inferiorly, the common hepatic duct medially and the inferior (visceral) surface of the liver superiorly.

First described by Jean-François Calot as an “isosceles” triangle in his doctoral dissertation in 1891, this anatomical space requires careful dissection before ligature and division of the cystic artery and cystic duct during cholecystectomy.

The modern definition of the limits of Calot’s triangle varies according to Calot’s original description, although the exact moment of this change is not entirely clear.

The structures within Calot’s triangle and their anatomical relationships may present difficulties to the surgeon, particularly when anatomical variations are found.

Solid knowledge of the normal anatomy of the extrahepatic biliary tract and vasculature, as well as the understanding of congenital variation, is therefore essential in the prevention of iatrogenic injury.

The authors describe the normal anatomy of Calot’s triangle and common anatomical anomalies. The incidence of structural injuries is discussed and new surgical techniques are reviewed to improve the visualization of Calot’s triangle.

Epónimo

Another name used to refer to this region is the Calot triangle. It is named after Jean-François Calot .

Notably, Calot’s original description of the triangle in 1891 included the cystic duct, the common hepatic duct, and the cystic artery (not the lower edge of the liver as commonly believed).

The hepatocystic triangle is the area joined by the cystic duct, the common hepatic duct and the hepatic margin.

Anatomy and location

The cystohepatic triangle is formed between the right side by the cystic duct, on the left side by the common hepatic duct and, above, by the lower surface of the liver.

It is a triangle oriented down between the cystic and common hepatic ducts. The triangle comprises the right hepatic artery, the cystic artery and the cystic lymph node of Lund.

Most aberrant segmental right hepatic ducts and arteries are usually touched in this triangle.

The accessory hepatic ducts terminate in the gallbladder or in the common hepatic duct or even in the bile duct and are responsible for the exit of bile from the wound after cholecystectomy.

Clinical significance

General surgeons often question medical students about this term and the name of the lymph node located within the triangle, the Mascagni lymph node or the Lund nodule, however, many often mistakenly call it “Calot nodule.” .

The latter is often enlarged due to inflammation of the gallbladder (eg, cholecystitis ) or biliary tract (eg, cholangitis) and can be removed along with the gallbladder during surgical treatment (cholecystectomy).

The Calot triangle, which contains the cystic artery, may also contain an accessory right hepatic artery or abnormal sectoral bile ducts. As a result, the dissection in Calot’s triangle is misguided until more lateral structures have been removed and the identification of the cystic duct is definitive.

According to the Surgical Education and Self-Assessment Program (SESAP 12) (produced and distributed by the American College of Surgeons), dissection in the Calot triangle is the most common cause of common bile duct injuries.

Importance

The cystic artery and the duct must be clearly defined to obtain the “critical vision of safety”. These structures are exposed by a careful dissection of the fibroactive tissue within the Calot triangle.

Once the fibroadipose tissue is removed, the cystic artery and the cystic duct are conclusively identified as the only two structures that pass to the gallbladder and the base of the hepatic bed is exposed by separating the lower part of the gallbladder from the liver . It is not necessary to see the common bile duct.

This is the critical view of safety and, once it is obtained, the cystic duct and the artery can be trimmed safely. If these structures are clearly seen, even in the presence of an abnormal anatomy, an iatrogenic lesion should be considered.

The Rouviere sulcus , a natural cleft in the right lobe, anterior to Segment 1, occurs in more than 80% of normal livers.

It is a useful anatomical milestone, but often ignored, to begin the dissection of Calot’s triangle and also to confirm its location.