Liver Flashcards
Methods for Liver Anatomy
Traditional: based on external appearance (lobes & contour)
Couinaud’s: based on functionality (hepatic & portal veins)
Layers of Liver
- Outer layer from visceral peritoneum
2. Glisson’s capsule
Glisson’s Capsule
Echogenic layer that surrounds liver, hepatic artery, portal vein, and bile ducts
Morrison’s Pouch
Space between liver & right kidney
Ascites
Fluid that accumulates the left & right sub-diaphragmatic spaces
Pleural effusion
Liquid around lungs (left & right sub-phrenic space)
Normal size of liver
13-15 cm
Average size of liver
15-17 cm
Atrophic
Smaller than normal
Hepatomegaly
Enlarged liver
Lobes of Liver
- Right
- Left
- Caudate
- Quadrate
What structure is posterior to the left lobe?
Aorta
What structure is anterior/posterior/inferior to the caudate lobe?
Anterior: Ligamentum venosum
Posterior: IVC
Inferior: Main portal vein
The main lobar fissure connects what 2 structures
Portal vein & neck of the gallbladder
Where is the quadrate lobe located?
Between the gallbladder fossa & falciform ligament
From which structures does the liver receive blood?
Hepatic artery & portal vein
What structures form the portal vein?
Superior mesenteric vein & splenic vein
What is the main source of blood to the liver?
Portal vein
From where does the hepatic artery orginiate?
Aorta > Celiac Trunk > Hepatic Artery
Portal Triad consists of
Hepatic artery, portal vein, common bile duct
Function of hepatic veins
Drain blood from liver into IVC
How does the left HV divide the liver?
Medial/lateral
How does the middle HV divide the liver?
Right/left
How does the right HV divide the liver?
Anterior/posterior
Where are the portal veins largest?
At the porta hepatis
Porta hepatis
Door of the liver, where portal triad enters
The portal veins run which direction
Horizontally & intrasegmentally
The hepatic veins run which direction
Vertically/longitudinally & intersegmentally
Where do hepatic veins increase in size?
As they run toward the IVC
Appearance of porta hepatis
Hyperechogenic, b/c it is surrounded by a fibro fatty channel
Falciform ligament
Divides liver into right/left
Main lobar fissure
Inferior to hepatic vein & superior to right portal vein & gallbladder neck
Right intersegmental fissure
Divides right lobe into anterior & posterior segments; identified by right heptatic vein
Left intersegmental fissure
Divides left lobe into medial & lateral segments; identified by left hepatic vein
Ligamentum teres originates from
the obliterated umbilical vein of fetus
Ligamentum teres originates from
ductus venosus of fetus
Average size of portal vein
13 mm
Average size of spleen
13 cm
Ligaments that anchor liver to abdomen
Coronary, right/left triangular ligaments
Main liver function tests
AST (SGOT) - aspartate aminotransferase ALT (SGPT) - alanine aminotransferase Albumin Bilirubin AFP - alpha fetoprotein CEA - carcinoembryonic antigen
Normal Anatomic Variants
- Reidel’s lobe
- Caudate lobe size
- Hepatic Veins
- Situs inversus
Reidel’s lobe
Extension of the right lobe
Situs inversus
Organ reversal to left side of body
Echogenicity of liver compared to spleen
Isoechoic
Echogenicity of liver compared to kidney
Isoechoic, or slightly greater than renal cortex
Echogenicity of liver compared to pancreas
Slightly hypoechoic
Fatty Infiltration is also known
Steatosis
2 most common cause of steatosis
Obesity & alchohol abuse
Steatosis ultrasound appearance
Increased echogenicity, obscure vessels, difficulty in penetration
Focal Fatty Infiltration
Areas of increased echogenicity, can appear as a hyperechoic mass/tumor
Focal Sparing
Area spared from fatty infiltration
Focal Sparing Ultrasound Appearance
Irregular shaped hypoechoic area
Hepatitis
Inflammation of the liver caused by the hepatitis A-F virus
Clinical Signs & Symptoms of Hepatitis
Anorexia, jaundice, nausea, fatigue, joint pain
Ultrasound Appearance of Acute Hepatitis
Normal, decreased echogenicity, larger portal veins, thickened gallbladder wall, enlarged and tender
What is the reasoning behind the appearance of a liver with acute hepatitis?
Because the liver is under attack from the virus, all the blood is rushing to the liver to fight off the attack. This causes to liver to be enlarged and tender. More blood = less echogenicity
Ultrasound Appearance of Chronic Hepatitis
Coarse echo pattern, increased echogenicity, decreased echogenicity in PV walls
What is the reasoning behind the appearance of a liver with chronic hepatitis?
Because the organ is dying, blood has left the vessel to tend to other organs. There is also less vasculature
Cirrhosis
Liver parenchyma is replaced by fibrosis and abnormal modules.
Fibrosis
Dead tissue/cells
Ultrasound Appearance of Early Cirrhosis
Hepatomegaly, fatty infiltration
Ultrasound Appearance of Chronic Cirrhosis
Coarse texture, ascites, dialated PV, portosystemic varices, hepatofugal portal flow, splenomegaly, recanalized ligamentum teres, enlarged caudate lobe
What is the reasoning behind the appearance of a liver with chronic cirrhosis?
Because the liver is starting to atrophy, the liver cannot process all the blood coming to the organ. Backed up blood leads to increased pressure around the liver which results in:
- Dilation of portal vein (Brings blood to heart)
- Increased blood flow to the spleen (PV leads to splenic vein)
- Ligamentum teres has restored blood flow
- Varices form (small blood channels)
Portal Hypertension
PV larger than 13 mm
Dilated splenic vein/SMV measurement
> 10mm
Hepatofugal
Away from liver
Hepatopetal
Towards liver
Budd-Chiari Syndrome
Blockage of hepatic veins; very urgent b/c hepatic veins → IVC → heart
Ultrasound Appearance of Budd-Chiari Syndrome
Compressed IVC, ascites, enlarged caudate lobe, splenomegaly
Cyst Requirements
- Anechoic
- Well defined walls
- Posterior enhancement
Cysts are most common in
Right lobe (bigger) & females
Hyatid Disease
Echinococcal Cyst, caused by parasitic worm
Mostly found in liver, can also be found in lung, brains, and bone
Ultrasound Appearance of Hyatid Disease
Simple cyst with or w/o wall calcification, mother cyst w/ daughter cyst, honeycomb/water lilly design
Pyogenic Abscess
Abscess caused by bacterial invasion of liver
Bacteria that cause pyogenic abscess
E. coli
Clostridium
Bacteriodes
Infection routes for pyogenic abscess
Biliary tree, portal vein, hepatic artery
Symptoms of Pyogenic Abscess
Fever, pain, nausea, vomiting, diarrhea
Lab Values for Pyogenic Abscess
Leukocytosis, increased LFTs, anemia
Ultrasound Appearance of Pyogenic Abscess
Irregular shape and walls, may have shadowing or comet tail artifact
Amoebic Abscess
Caused by amebas that liquefy hepatic tissue; can lead to death without treatment
Ultrasound Appearance of Amoebic Abscess
Subcapsular, low amplitude cyst fill in, thickened irregular walls, posterior enhancement
Signs/Symptoms of Amoebic Abscess
Abdominal pain, diarrhea, melena
Name the benign neoplasms
Cavernous hemangioma, focal nodular hyperplasia, adenoma, hematoma
Cavernous Hemangioma
Vascular structures filled w/ blood cells, most common benign liver tumor!
Ultrasound Appearance of Cavernous Hemangioma
Round, highly echogenic, well defined solid mass
Focal Nodular Hyperplasia
Very rare, benign tumor
2 masses caused by oral contraceptives
FNH, adenoma
Focal Nodular Hyperplasias are composed of
- Hepatocytes
- Kupffer cells
- Fibrous connective tissue & bile duct elements
Liver Cell Adenoma
Benign tumor
Increased incidence for adenoma with
- Oral contraceptives in women
- Steroid use in men
- Type 1 glycogen storage disease
Hematoma
Mass filled w blood, often caused by trauma
Ultrasound Appearance of Hematoma
If hematoma has old blood → hyperechoic
If hematoma has new blood → hypoechoic
Name the malignant neoplasms
Hepatocellular carcinoma (aka hepatoma, HCC), metastases
Increased risk for hepatoma can be due to
Hepatitis & cirrhosis
Ultrasound Appearance of HCC
Hepatomegaly, ascites, invasion of portal & hepatic veins, distorted parenchyma
Metastases
Cancer that has originated from another organ and spread to the liver, most common liver malignancy!
Signs/Symptoms of Metastases
Jaundice, pain, hepatomegaly
Ultrasound Appearance of Metastases
Lung: Bull’s eye/target
Colon: Hyperechoic
Liver/kidney: Moth eaten
Can also be calcified