**2. Anatomy of the gallbladder and the adjacent area**

To perform a successful gallbladder surgery, the surgeon has to know the anatomy of this region and also be aware of potential anatomical variations resulting in a potentially more difficult surgery.

#### **2.1 Biliary tract**

Most of the time, the intrahepatic biliary ducts consecutively join forming anterior and posterior segment ducts, which drain into the right hepatic duct, and medial and lateral segment ducts draining into the left hepatic duct. The union of

the right and left hepatic ducts in the porta hepatis leads to the formation of the common hepatic duct (CHD) with its distal end formed by cystic duct junction and variation in the length from 1.0 to 7.5 cm depending on the junction site with the diameter of 0.4 cm [3].

In most people, the cystic duct joins the common hepatic duct at an angle of 40° from the right side and runs parallel to the CHD for a shorter or longer distance on average for 17 mm [3]. In some cases, the cystic duct may cross the CHD posteriorly or anteriorly and join the CHD from the left side [3].

Common bile duct (CBD)/ductus choledochus is formed by the union of the CHD and the cystic duct with its distal end at the papilla of Vater in the duodenum [3]. If the cystic duct enters the duodenum separately, the common bile duct is absent [3]. Standardly the length of CBD is diverse between 5 cm and 15 cm with an average diameter of 6 mm.

Gallbladder is a pouch 7–10 cm long able to contain 30–50 ml of bile and located on the visceral liver surface in the proximity of the liver segments IV and V [3]. Liver and gallbladder are separated by the Glisson capsule's connective tissue and anteriorly, the gallbladder is covered with the peritoneum completely enfolding the *fundus* [3]. Body of the gallbladder contacts the superior and descending part of the duodenum and the transverse colon [3]. Infundibulum is the posterior part of the gallbladder body between the neck and cystic artery entrance [3]. Dilated infundibulum with a lateral bulge is called the Hartman's pouch, formerly thought to be a variation, however later regarded as a constant feature [3]. Gallbladder neck is an S-shaped narrowing continually proceeding into the cystic duct (**Figure 1**) [3].

## **2.2 Vasculature of the gallbladder**

The blood supply to the gallbladder is secured by the cystic artery, which commonly arises from the right hepatic artery (RHA) and runs towards the gallbladder

just right to the common hepatic duct through the hepatocystic triangle [3]. Venous drainage is secured by a number of small veins passing through the gallbladder bed to the liver from the hepatic site, and from the peritoneal site, small veins drain into the liver through the ascending veins of the common bile duct [3]. The lymphatic drainage is secured by the collecting trunks draining into the cystic node localised in the angle between the cystic and common hepatic ducts and into the hiatal node localised on the anterior border of the epiploic foramen [3].
