The gall bladder and surgery

 

The gallbladder is a gastrointestinal organ located within the right hypochondrial region of the abdomen. This intraperitoneal, pear-shaped sac lies within a fossa formed between the inferior aspects of the right and quadrate lobes of the liver.

The primary function of the gallbladder is to concentrate and store bile which is produced by the liver. As part of the gustatory response, the stored bile is then released from the gallbladder in response to cholecystokinin.

In this article, we shall look at the anatomy of the gallbladder – its structure, vasculature, innervation and lymphatic supply.

Anatomical Relations

The gallbladder is entirely surrounded by peritoneum, and is in direct relation to the visceral surface of the liver.

It lies in close proximity to the following structures:

• Anteriorly and superiorly – inferior border of the liver and the anterior abdominal wall.
• Posteriorly – transverse colon and the proximal duodenum.
• Inferiorly – biliary tree and remaining parts of the duodenum.

Anatomical Structure

The gallbladder has a storage capacity of 30-50ml and, in life, lies anterior to the first part of the duodenum. It is typically divided into three parts:

• Fundus – the rounded, distal portion of the gallbladder. It projects into the inferior surface of the liver in the mid-clavicular line.
• Body – the largest part of the gallbladder. It lies adjacent to the posteroinferior aspect of the liver, transverse colon and superior part of the duodenum.
• Neck – the gallbladder tapers to become continuous with the cystic duct, leading into the biliary tree.
• The neck contains a mucosal fold, known as Hartmann’s Pouch. This is a common location for gallstones to become lodged, causing cholestasis.

The Biliary Tree:

The biliary tree is a series of gastrointestinal ducts allowing newly synthesised bile from the liver to be concentrated and stored in the gallbladder (prior to release into the duodenum).

Bile is initially secreted from hepatocytes and drains from both lobes of the liver via canaliculi, intralobular ducts and collecting ducts into the left and right hepatic ducts. These ducts amalgamate to form the common hepatic duct, which runs alongside the hepatic vein.

As the common hepatic duct descends, it is joined by the cystic duct – which allows bile to flow in and out of the gallbladder for storage and release. At this point, the common hepatic duct and cystic duct combine to form the common bile duct.

The common bile duct descends and passes posteriorly to the first part of the duodenum and head of the pancreas. Here, it is joined by the main pancreatic duct, forming the hepatopancreatic ampulla (commonly known as the ampulla of Vater) – which then empties into the duodenum via the major duodenal papilla. This papilla is regulated by a muscular valve, the sphincter of Oddi.

CLINICAL RELEVENCE OF GALL STONES:

Cholelithiasis, commonly known as gallstones, are small lumps of cholesterol, bile salts or a mixture of the two, which may form within the gallbladder. They are relatively common and often asymptomatic. 

However, they may be associated with pain, jaundice and systemic upset (depending on the location of the gallstone, and the presence or absence of associated infection or inflammation).

Different terminologies are applied to distinguish between these pathologies:

Cholelithiasis – uncomplicated gallstones

Biliary colic – typically right upper quadrant pain following a fatty meal as gallstones obstruct the cystic duct during contraction of the gallbladder. Not associated with systemic upset

Cholecystitis – inflammation of the gallbladder. Pain is often associated with nausea, vomiting or fever

Choledocholithiasis –  gallstone within the common bile duct. Often causes deranged liver function tests.

Cholangitis – infection of the common bile duct often secondary to choledocholithiasis. Typically presents with right upper quadrant pain, fever and jaundice (Charcot’s Triad)

Once diagnosed, most symptomatic patients have surgical removal of the gallbladder (cholecystectomy); which is now often performed via laparoscopic (key-hole) surgery during the acute phase or once recovery has taken place (often at 6 weeks). In the interim, patients are prescribed analgesia and antibiotics when required

CALOT'S TRIANGLE:

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.

Borders

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).

Contents

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.
• Lymphatics

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.