Liver Flashcards
Anatomic location of liver
RUQ
superior and posterior bounds are diaphragm
lateral- ribs
inferior- GB, stomach, duod, colon, kidney, R adrenal
covered by glisson’s capsule and peritoneum
What defines the R and L lobes of the liver?
the plane formed by the GB fossa and the IVC
What is the falciform ligament?
goes bt liver and diaphragm
landmark bt the lateral and medial segments of the L lobe
What are the coronary ligaments?
They continue laterally from the falciform and end at the R and L triangular ligaments, which define the bare area of the liver (no peritoneum)
How many segments is the liver divided into?
8 parenchymal segments, based on arterial and venous anatomy.
T/F portal circulation gives the liver first access to all venous flow from the intestines.
True
Where does hepatic blood flow come from?
75% from the portal vein (splenic vein joins w SMV)
rest of it is from the hepatic artery, via the celiac axis.
How does blood leave the liver?
via the right, middle, and left hepatic veins to the IVC
What metabolic events occur in the liver?
Glucose is take up and stored as glycogen
Glycogen is broken down to maintain blood glucose leve.
FAs are oxidized to ketones for the brain to use
Proteins are made (coagulation factors, albumin, alpha globulin)
What coagulation proteins are made in the liver?
fibrinogen prothrombin prekallikrein high molecular weight kininogen factors 5, 7, 8, 9, 10, 11, 12
Which coagulation factors are dependent on vitamin K?
prothrombin
factors 7, 9, 10
How does warfarin (coumadin) affect coagulation?
It’s an anticoagulant, and affects the vit-K dependent pathways (prothrombin, 7, 9, 10)
Causes increased prothrombin time.
What are the digestive functions of the liver?
Makes bile
Metabolizes cholesterol
What is used to make bilirubin? How is bilirubin excreted?
Heme is used to make bilirubin
Bilirubin is first conjugated with glycine or taurine and then excreted in bile
What is the fn of bile?
It emulsifies fats so that they can be digested, and helps with vitamin uptake
T/F Bile salts excreted into the intestine are reabsorbed into the portal circulation
True
What is enterohepatic circulation?
The cycle of bile excretion and absorption- bile is excreted from the liver/GB and emulsifies fats, then is reabsorbed back into the liver via the portal circulation (which drains the intestines)
>95% of excreted bile is reabsorbed.
What is the rate-limiting step of cholesterol synthesis?
HMG-coA reductase
acetyl coA –> mevalonate
T/F cholesterol metabolism to bile salts occurs in the GB
False, it occurs in the liver.
What are the two detoxification pathways in the liver?
Phase I (CytP450) reactions- oxidation, reduction, hydrolysis Phase II- conjugation reactions. Imp for toxin clearance.
T/F the first hydroxylation of Vit D occurs in the liver
True
What cells of the liver mediate immunologic fns?
Kupffer cells (liver macrophages)
What are the kinds of benign liver tumors?
Hepatocellular adenoma Focal nodular hyperplasia Hemangioma (most common) Lipoma Only 5% of all liver tumors are benign tho.
What are the types of liver hemangiomas?
Capillary- no clinical consequence
Cavernous- can get to a large size and rupture
Use of what drug increases the risk of adenoma?
Oral contraceptives
HPE of benign liver tumors
If adenoma or hemangioma- can be asx or can px w dull pain.
Rupture - sudden severe pain
If lesions are large, they can be palpated, and they can cause jaundice (dt bile duct obstruction) or sx of gastric outlet obstruction, naus/vom
Focal nodular hyperplasic is usu asx
Dx Eval of benign liver tumors
Usu found incidentally
If there is an adenoma hemorrhage, it can cause hepatocellular necrosis and rise in transaminase levels.
Hemangioma- can cause consumptive coagulopathy.
US- to differentiate cysts from solid lesions
CT- to distinguish bt malignant and benign
How do adenomas appear on CT?
Low density lesion
How do focal nodular hyperplasias appear on CT?
Filling defect or central scar
How do hemangiomas appear on CT?
Have peripheral enhancement after contrast is given
T/F you should not biopsy a hemangioma
True, bc of risk of bleeding
Rx for adenoma
If using OCPs, stop
If it doesn’t regress, resect if pt is healthy bc of risk of malignant degeneration or hemorrhage.
Relative contraind for resection- technically difficult to resect; large size and a lot of liver would need to be removed
Rx for symptomatic hemangioma
Resect
Rx for focal nodular hyperplasia
Don’t resect, it’s not malignant and doesn’t cause sx usu.
Only exception is if you are already doing laparotomy and it’s small and peripheral.
What are the types of malignant liver cancer?
Hepatoma (aka hepatocellular carcinoma)
Mets from other sources
T/F Hepatoma (hepatocellular carcinoma) has a higher incidence in the US than worldwide.
False. Low rates in the US, high abroad.
What factors predispose to hepatoma?
Cirrhosis Hep B (cause of cirrhosis) alcoholism fungal aflatoxins hemochromatosis (iron overload) smoking vinyl chloride OCPs
HPE for hepatoma (hepatocellular carcinoma)
weight loss, RUQ/shoulder pain, weakness
hepatomegaly
signs of portal HTN- splenomegaly and ascites
Jaundice in 50%
Mets often indistinguishable from primary.
Dx eval for hepatoma
Abn LFTs AFP XR- benign vs malignant US- cystic vs solid lesions CT or MRI- shows multiple lesions, shows anatomy better For hemangioma- hepatic arteriography.
Rx for hepatoma
Resect tumor (but dep on comorbid dz, location, size)
Do a wedge resection if possible.
If small tumor and can’t be resected, or if cirrhosis- consider liver txplant
Overall, pgx is poor
Where do mets to liver come from?
Most frequent: lung. Then colon, pancr, breast, stomach
Should liver mets be resected?
In general no
But if it’s from colon ca, resection of up to 3 lesions can help.
What is the cause of liver abscesses?
Usu dt bacteria, amoebas, or Echinococcus (tapeworm)
Where do bacterial abscesses come from?
intra-abd infection in the appendix, GB, or intestine
can also be dt trauma or complication from surgery
What bacteria cause liver abscess?
Gut flora- Ecoli, Klebsiella, enterococci, anaerobes(Bacteroides)
T/F amoebic abscesses are a frequent complication of GI amebiasis
False. They are not so common, only occur in 3-25%
Risk factors of amoebic abscess
HIV
alcohol abuse
foreign travel
What is the most common cause of liver abscess worldwide?
Echinococcus (tapeworm)
Rare in the US tho.
Seen in eastern Europe, Greece, S Africa, S America, Australia
HPE for liver abscess
usu non-specific, vague abd pain, weight loss, malaisem anorexia, fever.
ask about travel for Echinococcus
Liver may be tender/enlarged, may have jaundice
If rupture of abscess- peritonitis, sepsis, circulatory collapse.
Dx eval for liver abscess
WBC and transaminase are high
If amebic abscess- will have Ab to amoeba
if echinococcus- will have eosinophilia and +heme agglutination test
US or CT shows lesion
If multiple cysts/”sand” on CT- Echinococcus
When should you sample a liver abscess?
If it’s pyogenic- it usually shows the causative organism. (but doesn’t show amoebas)
DON’T aspirate Echinococcal cysts bc can contaminate the peritoneal cavity.
Rx for pyogenic abscess
Abx
sometimes w percutan or open drainage
Rx for amoebic abscess
metronidazole (flagyl) +/- chloroquine
only drain if there are complications/rupture
Rx for Echinococcal abscess
open procedure to remove.
give scolicidal agents (ethanol or 20% NaCl) directly into cyst, then drain it. Be careful not to spill worms into peritoneum!!
What are the three general categories of cause of portal HTN?
presinusoidal
sinusoidal
postsinusoidal
Presinusoidal causes of portal HTN
schisto
portal vein thrombosis
Sinsuoidal causes of portal HTN
cirrhosis (usu dt alcohol or Hep B or C)
Post-sinusoidal causes of portal HTN
Budd-Chiari syndrome (hepatic vein occlusion)
pericarditis
R-sided HF
What is a varices?
an abnormally dilated vessel (usu venous)
Bleeding varices are a life-threatening complication of portal HTN
When there is portal HTN, what vessels become the lowest-resistant route for blood flow?
hemorrhoidal veins, umbilical vein, coronary vein.
the coronary vein empties into the plexus of veins draining the stomach and esophagus.
Engorgement of these veins means increased risk for bleeding into stomach/esophagus.
HPE for portal HTN
Hx of alcoholism, hep, prev variceal hemorrhage
Ascites, jaundice, “cherub face” spider angioma, testicular atrophy, gynecomastia, palmar erythema
Dx Eval for portal HTN
increased LFTs
abn clotting times, albumin level
T/F in pts with advanced cirrhosis and portal HTN, increased liver enz may return to normal as the cirrhosis progresses
True. The amt of functioning parenchyma decreases with increased cirrhosis. So there will not be as much increase in liver enz, since there is nothing to make them.
Rx for portal HTN
B-blockers (to decrs risk of bleeding)
Endoscopic surveillance and banding to prevent bleeding.
Rx for portal HTN w upper GI bleed
large bore IVs and immed volume resuscitation
NG tube
if can’t be lavaged clear, emergency endoscopy for dx and therapy.
What should you do if endoscopy fails to control upper GI bleed?
balloon tamponade with Sengstaken-Blakemore tube and vasopressin
put gastric balloon in stomach, then inflate esophageal balloon. (this can cause ischemia tho, so be careful)
What is TIPS?
Transjugular intrahepatic portosystemic shunting.
put metallic shunt from hepatic vein to R portal vein (place it via IJV catheter)
good for controlling acute bleeding.
After initial episode of bleeding varices is controlled, what should you do?
40% will develop a bleeding complication, 70% will rebleed- so consider a definitive procedure(?)
