The hepatobiliary triangle (or cystohepatic triangle) is an anatomic space bordered by the common hepatic duct medially, the cystic duct inferiorly and the superior border to the cystic artery.
General surgeons frequently quiz medical students on this term and the name for the lymph node located within the triangle, Calot’s node. The latter is frequently enlarged due to inflammation of the gallbladder (e.g. cholecystitis) or the biliary tract (e.g. cholangitis) and may be removed along with the gallbladder during surgical treatment (cholecystectomy).
Calot’s triangle, containing the cystic artery, may also contain an aberrant / accessory Right Hepatic Artery or anomalous sectoral bile ducts. As a result dissection in the triangle of Calot is ill-advised until the lateral-most structures have been cleared and identification of the cystic duct is definitive. According to SESAP 12 (produced and distributed by the American College of Surgeons) dissection in the triangle of Calot is the #1 cause of common bile duct injuries).
Variations of the Cystic Artery
Diagram shows cystic artery classification based on the relationship of the cystic artery to the Calot triangle. Cystic arteries can be classified into seven subtypes on the basis of their relationship to the Calot triangle, which consists of the common hepatic duct, cystic duct (CD), and undersurface of the liver (L), and within which minute arteries frequently may be found. Types 1, 2, and 3 are associated with one cystic artery (CA), two cystic arteries, and three or more cystic arteries, respectively. Each is further subdivided as follows: Type 1a indicates one cystic artery courses at least partly through the Calot triangle. Type 1b indicates one cystic artery courses outside the Calot triangle. Type 2a indicates two cystic arteries course at least partly through the Calot triangle. Type 2b indicates one artery courses at least partly through the Calot triangle and the other artery courses outside the Calot triangle. Type 2c indicates both cystic arteries course entirely outside the Calot triangle. Type 3a indicates all arteries course through the Calot triangle. Type 3b indicates all but one artery course at least partly through the Calot triangle, while the remaining artery courses outside the Calot triangle. Type 3c (not shown) indicates two or more arteries course outside the Calot triangle. CBD = common bile duct, GB = gallbladder.
(from Radiology July 2008 vol. 248 no. 1 124-131 )
Jean-Francois Calot (1861–1944) was born in Arrens, France. He served as a surgeon in Berck-sur-Mer at the Rothschild Hospital and the Hospital Cazin-Perrochaud. For his doctoral thesis in 1890 at Paris, he chose the topic of cholecystectomy and dealt in detail with the anatomy and technique involved. He asserted that working in the
region of the cystic duct “is the more delicate part of the operation.” He described an isoceles triangle with the common hepatic duct as its base, the inferior edge of the cystic duct and the superior border to the cystic
artery as its sides. He insisted this configuration be clearly delineated before clamps were applied. In this, Calot bore out the dictum that “the surgeon should work by sight and not by faith.” The bulk of Calot’s later work was in orthopedic surgery, in particular, surgery required in treatment of wounds of war.