GIT short answer

Question 1

Describe/draw the liver using Couinaud’s classification of the liver segments

Answer 1

The Couinard classification divides the Liver into 8 independently functional segments. This division is based on the right and left branches of the hepatic artery and the portal vein with tributaries of bile (hepatic) ducts following.

The hepatic veins run in three vertical planes radiating from the intrahepatic IVC separating the liver into 4 sections. A section is two segments on top of eachother.

• Right hepatic vein is located in the right intersegmental fissure
• Middle hepatic vein lies in the main lobar fissure, divides the liver into right and left lobes. This vertical plane runs from the inferior vena cava to the gallbladder fossa and is known as Cantlie’s line.
• Left hepatic vein is located in the left intersegmental fissure

A horizontal plane further divides the liver, known as the portal plane where the portal vein bifurcates and becomes horizontal, dividing each section (or sector) of the liver into superior and inferior segments.

Each segment has its own vascular inflow, outflow and biliary drainage. In the centre of each segment, there is a branch of the portal vein, hepatic artery and bile duct. In the periphery of each segment there is vascular outflow through the hepatic veins.

Segment 1: Caudate lobe
The remainder of the segments (2 to 8) are numbered in a clockwise fashion starting superiorly in the left hemiliver
Segment 2: Lateral segment left lobe (superior)
Segment 3: Lateral segment left lobe (inferior)
Segment 4: medial segment left lobe ( separated into 4a superior and 4b inferior (quadrate lobe))
Segment 5: Anterior segment right lobe (inferior)
Segment 6: Posterior segment right lobe (inferior)
Segment 7: Posterior segment right lobe (superior)
Segment 8: Anterior segment right lobe (superior)

Question 2

List 3 causes of liver cirrhosis.

Answer 2

Alcoholic liver disease and hepatitis C are the most common causes in the Western world, while hepatitis B prevails in most parts of Asia and sub-Saharan Africa.

Question 3

List 3 causes of hepatocellular carcinoma

Answer 3

• Viral Hepatitis B and C
• NASH - non-alcoholic steatohepatitis
• Cirrhosis

Question 4

What is ascites? why does it occur. Explain the mechanism

Answer 4

Ascites is defined as an abnormal amount of intraperitoneal fluid and a common complication of diseases presenting with portal hypertension. The most common cause of ascites is cirrhosis. The mechanism by which ascites develops in cirrhosis is multifactorial. Severe sinusoidal portal hypertension and hepatic insufficiency are the initial factors. Ascites occurs when there is a disruption in the pressure forces between intravascular and extravascular fluid spaces, which allows extravascular fluid to accumulate in the anterior peritoneal cavity.

Question 5

Define pancreatitis. What is the common cause? Explain one possible complication of pancreatitis

Answer 5

Acute pancreatitis is described as inflammation of the pancreas resulting in the release of digestive enzymes (trypsin, amylase and lipase) which then may cause further complications by autolysis of the pancreas itself resulting in interstitial oedema, necrosis and haemorrhage and also the destruction of surrounding tissues such as fat.
Gallstones & alcohol abuse are the most common causes and accounts for more than 85 % of all patients who develop pancreatitis.
A possible complication of acute pancreatitis is necrotic pancreas tissue which may cause
• continuous fever, abdominal pain, and inability to tolerate a diet,
• development of infection in the dead pancreatic tissue can give rise to life-threatening infection in the blood,
• separation of the dead pancreas from the remaining living pancreas often leads to leakage of pancreatic juice into the abdomen. This is often associated with development of a condition called a pancreatic pseudocyst and
• damage to surrounding structures in the abdomen from the inflammation and leakage of pancreatic juice such as the colon, blood vessels, splenic vein, and the duodenum.

Question 6

Describe the presentation, aetiology and risk factors for gallstones

Answer 6

Gallstones occur in ~10% of the population with a predominance in women (F: M = 2:1). The prevalence increases with age in both sexes.
Gallstones may be symptomatic in only 25% of cases. The most common presentation is with biliary colic (right upper quadrant or epigastric abdominal pain or discomfort, especially after a fat-rich meal). Other symptoms include belching, bloating, flatulence, heartburn, and nausea. Abdominal pain is often referred to the right shoulder tip.
Jaundice and dark urine occur in patients with gall stones when a stone migrates from the gall bladder into the common bile duct, blocking to flow of bile out of the liver. Dark urine results from excess bilirubin excreted by the kidneys. Jaundice is a yellow color of the skin and eyes that results from excess bilirubin deposited in the skin.

There are three main pathways in the formation of gallstones:
• Cholesterol supersaturation: Normally, bile can dissolve the amount of cholesterol excreted by the liver. But if the liver produces more cholesterol than bile can dissolve, the excess cholesterol may precipitate as crystals..
• Excess bilirubin: Bilirubin, a yellow pigment derived from the breakdown of red blood cells, is secreted into bile by liver cells. Certain hematologic conditions cause the liver to make too much bilirubin through the processing of breakdown of hemoglobin. This excess bilirubin may also cause gallstone formation.
• Gallbladder hypomotility or impaired contractility: If the gallbladder does not empty effectively, bile may become concentrated and form gallstones.

Common risk factors for cholesterol gallstones include:
•	female sex
•	middle age
•	obesity
•	positive family history
•	recent rapid weight loss