HPB Flashcards
Describe the course and tributaries of the portal vein.
Formed by the confluence of the superior mesenteric and the splenic vein. It lies anterior to the IVC and posterior to the head of the pancreas and first part of duodenum.
Other tributaries include:
R&L gastric veins
Superior pancreaticoduodenal
Cystic vein
Peri-umbilical vein in the ligamentum teres
It ascends in the free edge of the lesser omentum posterior to the bile duct and hepatic artery
At the porta hepatis it divides into two and supplied the respective halves of the liver
Describe the ligaments of the liver.
The falciform ligament: attaches the anterior surface of the liver to the abdominal wall. It splits the anatomical lobes of the liver. The free border is the ligamentum teres (the remnant of the umbilical vein).
The R and L coronary ligaments attach the R and L lobes of the liver to the diaphragm. It starts from the falciform ligament and diverges at the superior aspect. It surrounds the bare area.
The R and L triangular ligaments are the edges of the coronary ligaments.
What is the relationship of the liver and the omentum?
The lesser omentum emerges from the porta hepatis to the lesser curve of the stomach. It consists of the hepatogastric ligament and the hepatoduodenal ligament.
Where are the hepatic recesses and what are their clinical signficance?
Subphrenic: between diaphragm and anterior liver.
Subhepatic: between inferior liver and the transverse colon
Morrisons pouch: potential space between visceral liver and R kidney. This is the deepest part of the peritoneal cavity when supine.
They are clinically significant as they are sites of fluid collection and therefore abscess sites in infection
How many lobes does the liver have?
8
Caudate (on posterior aspect between the IVC and the ligamentum venosum.
Quadate: anterior, latral to the falciform ligament.
2 and 3 are lateral,
5,6,7,8 are medial
What are the anatomical and functional lobes of the liver?
Anatomical: R and L divided by the falciform ligament.
Functional: R and L divided by an imaginary line between GB and IVC
What is the microscopic structure of the liver?
The hepatocytes are arranges into lobules which are hexagonal and are drained by a central vein. Peripherally they have portal triads with a sinusoid, portal vein and hepatic artery alongside lymphatics and branches of the vagus nerve.
What is the blood supply to the liver?
70% is via the portal vein (formed by the confluence of the SMV and splenic vein behind the neck of the pancreas)
30% is via the hepatic arteries (from the coeliac trunk).
30% of people have accessory hepatic arteries arising from the SMA and the L gastric.
Describe the venous drainage of the liver.
The L hepatic vein drains the functional left lobe (segments 2 and 3)
The middle hepatic vein drains segments 5 and 8 which drains into the R hepatic.
The R hepatic drains lobes 6 and 7.
The caudate drains directly into the IVC`
All hepatic veins drain into the IVC.
What is the porta hepatis?
This is a fissure extending across the posterior R lobe transmitting the common hepatic duct, common hepatic artery and the portal vein (+ lymphatics and nerves)
What is the nerve supply to the liver?
The hepatic plexus contains sympathetic nerves from the coeliac plexus and parasympathetic fibres from the Vagus nerve.
Both enter via the porta hepatis.
Glisson’s capsule is also innervated by the lower intercostal nerves.
Describe the lymphatic drainage of the liver.
Anterior: hepatic lymph nodes to coeliac nodes.
Posterior: phrenic and posterior mediastinal
What is the surface anatomy of the liver?
Draw a line between the 3 points:
Mid axillary line of the 10th costal cartilage on the Right, the 4th intercostal space in the midaxillary line on the right and the 5th intercostal space midclavicular line on the left
What are the functions of the liver?
- Protein and Ammonia metabolism (including albumin, globulin, fibrinogen, CRP, clotting factors, angiotensinogen)
- Vitamin metabolism (vitamin D)
- Carbohydrate metabolism (gluconeogenesis and glycogenolysis)
- Lipid metabolism
- Immune function.
How does liver failure affect clotting?
Almost all the clotting factors are synthesised by the liver.
Vitamin K is essential to the carboxylase enzyme that makes factors, 2,7,9,10 and protein C and S and therefore if no bile is produced vitamin K cannot be absorbed.
How does lipolysis occur in the liver?
Triglycerides form fatty acids and glycerol.
Fatty acids then bind to albumin to become soluble and transport to the liver. Glycerol enters the hepatocytes and undergoes the glycolysis pathway.
Fatty acids undergo beta-oxidation and enter the TCA cycle to form ATP.
Excess acetyl CoA from this process is converted into ketone bodies which can be used as energy.
What does liver failure cause?
- Increased ammonia leading to Encephalopathy.
- reduced clotting factors leading to bleeding
- reduced CRP and acute phase proteins therefore immunosuppression
- reduced lipid and carbohydrate metabolism leading to lactic acidosis and hypoglycaemia
- reduced albumin leading to ascitis.
Describe the lifecycle of bilirubin.
Reticuloendothelial cells (macrophages responsible for the maintenance of blood) metabolise haem and globin. The iron from haem is recycled and the remaining substance is called bilividen.
Bilividen then becomes unconjugated bilirubin, this then conjugates with albumin and travels to the liver.
Once in the liver glucoronic acid is added via the enzyme gluconyl transferase to form conjugated bilirubin which is water soluble and therefore can be excreted in bile.
The bile is then excreted in bile and once in the colon bacteria deconjugate it to urobilinogen and stercobilin. Stercobilin is excreted in faeces and urobilinogen is reabsorbed into the enterohepatic circulation whilst some will be excreted as urobilin in urine
What is the purpose of the enterohepatic circulation?
This is where bile salts are reabsorbed in the terminal ileum and then pass via the portal system back to the liver where they can be reabsorbed.
What are the causes of jaundice?
Prehepatic:
Will have high unconjugated bilirubin, normal ALP, AST, PT and normal urine/stool.
Causes include:
- haemolytic anaemia (malaria and sickle cell crisis)
- Spherocytosis
- ABO incompatibility
Hepatic:
Will have high unconjugated or high conjugated bilirubin, high AST , high ALY, high PT (not correctable with VitK)
Caused by hepatocellular dysfunction including cirrhosis, hepatitis, toxins, TPN, haemochromatosis.
Post-hepatic:
Will have a high unconjugated bilirubin with normal ALT, high ALP, prolonged PT (correctable with VitK), often pale stools and dark urine.
Caused by bile duct obstruction.
What are the drug causes of Jaundice?
Hepatic Jaundice:
- paracetamol
- amiodarone
-diclofenac
-fluconazole
- heparin
- labetalol
Obstructive:
- co-amoxiclav
- flucloxacillin
- erythromycin
-cotrimoxazole
What are some causes of post-operative Jaundice?
Operative complications:
- retained CBD stone
-CBD injury
Anaesthetic complications:
- drug induced hepatitis
- hypotension causing liver ischaemia
Pre-existing conditions:
- decompensation of pre-existing liver failure
Other:
- haemolysis secondary to major transfusion
- TPN
What is the embryological structure that forms the portal vein, SMV and splenic vein?
The vitilline veins
Why do caput medussae form?
In adults a small lumen still persists in the ligamentum teres (remnant of the umbilical vein) therefore in portal HTN it can recannulate and forms a site of porto-systemic anastamosis and this causes the dilatation