Cholelithiasis

Notes

Definition & classification

Cholelithiasis (gallstones) refers to the development of a solid deposit or ‘stone’ within the gallbladder.

Though largely asymptomatic in a significant proportion of patients they become problematic. In the UK around 60,000 cholecystectomies are performed each year.

Cholelithiasis stats

Classically gallstones are categorised by their composition:

  • Cholesterol: the most common type found in western populations.
  • Pigmented: dark stones composed of bilirubin.
  • Mixed: a combination of the above. 

Anatomy

The gallbladder is a small organ with a capacity, in an adult, of about 50ml. 

A diverticulum, the gallbladder is continuous with the cystic duct and thus common hepatic duct.  It measures between 7-10 cm in an adult. It receives a blood supply from the cystic artery. This vessel has variable origin but most commonly arises from the right hepatic artery.

Note: Hartmanns pouch refers to dilatation at the neck of the gallbladder typically secondary to cholelithiasis. 

The biliary tree is a ductal system that transmits bile produced by hepatocytes to the second part of the duodenum (via the ampulla of Vater). By convention it is divided into intrahepatic and extrahepatic ducts. Here we will focus on the extrahepatic ducts.

Biliary tree anatomy

The right and left hepatic duct converge to form the common hepatic duct. The gallbladder meanwhile is drained by the cystic duct. The cystic duct and common hepatic duct converge to form the common bile duct.

The common bile duct forms a common channel with the pancreatic duct just proximal to the ampulla of Vater. The ampulla of Vater is an orifice that allows bile to drain into the second part of the duodenum, it is surrounded by the sphincter of Oddi. 

Aetiology & pathophysiology

The gallbladder stores bile where it is concentrated through absorption of water and electrolytes.

Bile is secreted hepatocytes into the biliary circulation. It is composed of bile acids (or salts), phospholipid, bilirubin, cholesterol and water. Imbalance in composition and stasis leads to stone formation.

Stone composition

The majority of gallstones in the developed world are composed primarily of cholesterol (80%). Increased cholesterol secretion relative to other components of bile, increased concentration or prolonged stasis may lead to cholesterol stones.

Pigment stones (10-15%) are formed from bilirubin. They are seen in patients with increased red cell turnover.

Symptomatic disease

Gallstones are normally asymptomatic. However in a proportion of patients they may cause a biliary colic. This is an acute, severe, RUQ pain that tends to be self-limiting.

A gallstone may progress through the biliary tree becoming impacted in the cystic duct or the common bile duct. Here it impairs biliary drainage leading to stasis and infection.

Impaction within the cystic duct leads to acute cholecystitis, an infection of the gallbladder.  It presents with signs of infection in addition RUQ pain and guarding.

Impaction in the common bile duct impairs drainage of bile from the liver. This leads to acute cholangitis with an infection and obstructive jaundice.

Biliary pathology

Clinical features

Biliary colic

  • Intermittent RUQ pain
  • Nausea
  • Bloating

Acute cholecystitis

  • RUQ pain
  • Guarding
  • Murphy's sign
  • Fevers
  • Tachycardia
  • Hypotension

Acute cholangitis

  • Fevers*
  • Jaundice* 
  • RUQ pain*
  • Hypotension
  • Confusion

* Charcot's triad

Investigations

Bedside

  • Observations
  • BM
  • Urine dip
  • Pregnancy test (any woman of child-bearing age)

Bloods

  • Full blood count (FBC)
  • Urea & electrolytes (U&Es)
  • CRP
  • Liver function tests (LFTs): an ‘obstructive picture’ may be demonstrated by the liver function tests with a raised bilirubin and ALP.
  • Amylase

Imaging

Ultrasound: used to demonstrate gallstones or a dilated common bile duct.

Computed tomography: may be used to demonstrate cholecystitis and exclude alternative causes of symptoms. It is useful in the diagnosis of ascending cholangitis. 

MRCP: offers excellent visualisation of the biliary tree and any calculi present.

Special

ERCP: involves the endoscopic intubation of the ampulla of Vater. It offers excellent views of the biliary tree whilst allowing therapeutic intervention such as drainage. 

Management

Biliary colic

In the acute phase patients should be given analgesia and anti-sickness to manage their symptoms.

A low-fat diet may be trialled with some patients receiving significant benefit. Typically however once gallstones have become symptomatic, cholecystectomy is indicated. It is known that once they have become symptomatic they are likely to be troublesome in the future. A routine surgical review with a view to surgery should be arranged.

Acute cholecystitis

Acute cholecystitis requires hospital-based management. Initial management should follow an ABC approach. Intravenous fluids and antibiotics should be commenced. 

Some centres offer ‘hot’ laparoscopic cholecystectomy where surgery is arranged within 72 hours of the onset of symptoms. If this is not available interval surgery indicated after a period of recovery. 

Acute cholangitis

Acute cholangitis requires hospital based management. Initial management should follow an ABC approach. Intravenous fluids and antibiotics should be commenced. 

Drainage of the infected biliary system is key to effective management. This is achieved utilising non-operative techniques. ERCP may be used to place a biliary stent to relieve the obstructed system. If this fails percutaneous transhepatic biliary drainage effectively drains the biliary tree.

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