Biliary and Liver Flashcards
abnormal development of intrahepatic bile ducts due to ductal plate malformation are likely the underlying cause of which
- congenital hepatic fibrosis with cystic kidney disease
2. ciliopathies- joubert, meckel-gruber, ivermark syndrome
What direction do bile duct develop occur
-start at the hilum and progress to the periphery of the liver
How does bile get from the liver to the duodenum
- Bile passes from canaliculi to canals of Hering
- Canals of Hering empty into the interlobular bile ducts
- Interlobular biliary ducts join larger portal tract bile ducts
- Portal tract bile ducts join to form right and left hepatic ducts which form the common hepatic duct at porta hepatis
- Cystic duct joins common hepatic duct to form common bile duct
- common bile duct and pancreatic duct join at ampulla of vater at 2nd portin of duodenum
What is the vascular supply of the intrahepatic biliary ducts
-the hepatic artery
What conditions does intrahepatic bile duct occur
- chronic biliary tract obstruction
- primary sclerosing cholangitis
- primary biliary cirrhosis
- ischmia, hepatic artery thrombosis
- chronic GVHD
- Chronic graft rejection
Paucity of intrahepatic bile duct
- Premature neonates
- Alagille syndrome
What are the 3 tissue layers of the gallbladder
- mucosa
- muscular propria
- serosa
No muscularis mucosa or submucosa
Risk factors for gallstones
- Age: bimodal distribrution in peds
- Gender: 3:1 female:male
- Obesity: responsible for majority of recent increase in nonhemolytic cholelithiasis
- related to increase dietary intake and hypersecretion of cholesterol into bile a well as gallbladder (GB) dysmotility
- insulin resistance may increase cholesterol synthesis - Hemolytic disease: sickle cell, thalassema, hereditary spherocytosis, Gilbert syndrome and wilsons
- Meds
- Genetics/ethnicity: PFIC - heterozygous mutations in ABCB4
- TPN/biliary stasis
- bowel resection/ileal disease
- Other: down syndrome, hypertriglyceridemia and pregnancy
Medications that result in choledocholithiasis
- OCP : cholesterol hypersecretion
- Ceftriaxone: secreted in bile and then precipitates with Ca2+ into an insoluble salt to form sludging and pseudoliths
- Lasix
- Cyclosporine
- Octreotide: biliary sludging though to be due to GB dysmotility
What are the steps in the bile cycle
a. breakdown of RBC = formation of lipid-soluble bilirubin
b. bilirubin (water insoluble) binds to albumin and picked up by hepatocytes
c. bilirubin conjugated in liver to glucuronic acid (water soluble) and secreted into ductules (3% of bile)
d. oxidation of cholesterols in hepatocytes to produce bile acids (cholic and chendeoxycholic acid)
e. BA conjugated with taurine and glycine to make them more soluble at acidic pH and less likely to preceipitate with Ca when secreted into bile (61% of bile)
f. other main components of bile:
- fatty acids (12%)
- cholesterol (9%)
- protein (7%)
- inorganic salts/metals (5%)
- phospholipids (3%)
- GB absorbs water, Cl- and H2O and concentrates bile 5-10x
- intestinal bacteria create 2dary bile salts by 7 alpha-dehyroxylation
- bile salts are reabsorbed TI and colon to help maintain BA pool via enterohepatic circulation
How are cholesterol stones formed
- increased secretin of cholesterol and/or decrease secretion of bile = supersaturated bile
- usually from increased dietary intake
- to much cholesterol can’t be solublized into micelles = cholestrol crystals and microliths
- leads to frank gallstones intra- or extra-hepatically
Risk factors for cholesterol stones
- female
- pregnancy
- obesity
- hypertriglyceridemia
- OCP use
Characteristics of cholesterol stones
- yellow/white
- > 50% cholesterol by weight
- radiolucent due to decrease Ca content
What are the characteristics of black pigment stones
increased unconjugated bilirubin combined with ionized Ca2+ to form calcium bilirubinate
What are the etiologies of Black Pigment stones
- decreased conjugation activity of uridine diphosphate glucuronosyltransferase (UGT1-A1) in Gilbert syndrome
- excessive bilirubin load overwhelming bilirubin conjugation as in hemolytic anemia
- decreased bile pool (ileal disease)
- TPN use (decrease BA reabsorption, stasis, decreased acidification of bile = decreased solubility of bile
- increase beta-glucoronidase activity = increased deconjugation of previous conjugated bilirubin
- CF/pancreatic insufficiency: via increased enterohepatic circ of bili and decreased bile reabsorption
Characteristics of black pigment stones
- brown/black color
- > 50% are radiopaque due to increased Ca content
- usually > 1 stone
- no female preponderance
How are brown pigment stones formed
-increased microbial beta-glucuronidase activity in bacterial or helminthi infections = increased deconjugation of bilirubin in bile
- infection and stasis = increased mucin production, the nidus for stone formation
- increased unconjugated bilirubin in bile = calcium bilirubinate stones
- also contain large amounts of fatty acids
Risk factors for brown pigment stones
-bile stasis and bile duct abnormalities = form stone w/n CBD
Characteristics of brown pigment stones
- brown to orange in color due to increase Ca2+ bilirubinate concentration
- usually Ca2+ content still too low to be radiopaque
What are microlithiasis stones formed from
- < 3 mm
- from precipitation of cholesterol monohydrate crystals, Ca 2+ bilirubinate, Ca2+ phosphate, Ca2+ carbonate and Ca2+ salts of fatty acids
Risk factors for microlithiasis
- PN
- fasting
- rapid weight loss
- systemic infection
- biliary stasis
- GB dysfunction
How can urso work for gallstones
-decrease cholesterol saturation in bile and may dissolve cholesterol stones
Etiology/pathogenesis of acute calculous cholecystitis
-gallbladder stasis common to all causes
1 Cholelithiasis
2. external compression of biliary tree with stasis
3. trauma
4 Structural duct abnormalities
5. Microlithiasis may be underdiagnosed causse of cholecystitis
Songraphic findings of acute calculous cholecystitis
- Gallbladder wall thickening: > 3.0-3.5 in some pediatric reports and > 4-5 in adults
- Gallstones
- Pericholecystic fluid
- Sonagraphic murphy’s sign
What HIDA scan finding is consistent with cholecystitis
- Technetium 99m labeled IDA given IV taken up in the liver, secreted into bile and concentrated into GB
- normal IDA hepatic uptake with decrease conc in GB bile after 60 mins consistent with cholecystitis
- morphine administration reduces fall positives by increaesing sphincter of oddi pressure - back pressure in CBD and force more radionuclide into GB
False positives for HIDA scan for cholecystitis
- obstruction of cystic duct by stone, inflammation or tumor
- hyperbili
- severe parenchymal liver disease
- prolonged fasting or TPN - full gallbladder resists further filling
- prior sphincterotomy - decrease resistance to bile out of the gallbaldder
Complications of acute calculous cholecystitis
Complications of cholecystectomy
- Gallbladder perf
- abscess
- empyema
- gangrene of GB
- Perforation of GB
- pancreatitis
Conditions associated with acute acalculous cholecystitis
- sepsis
- gastroenteritis
- abdominal trauma/surgery
- extensive burns
- shock/cardiac resus
- IV nutrition and prolonged fasting
- systemic inflammatory disease- SLE, kawasaki, Polyarteritis nodosa
- Congestive heart failure
Pathophys of acalculous cholecystitis
-gallbladder stasis and/or ischemia
Risk factors for acalculous cholecystisis
- prolong fasting
- TPN
- IV opiate narcotics
- volume depletion
- multiple transfusions
- sepsis
What is chronic acalculous cholecystitis/biliary dyskinesia
-abnormal gallbadder contractility as measured by decreased GB ejection fraction (EF) on HIDA
Clinical features of biliary dyskinesai
- chronic RUQ pain in absence of other findings with normal imaging of GB
- fatty food causes abdo pain
- normal LFT
-surgery often shows chronic inflammatory changes of GB
How do you dx biliary dyskinesia
- HIDA scan before and after CCK or fatty meal stimulation used to calculate GB EF
- GB EF = difference btw amount of tracer in GB before and after CCK or fatty meal stimulation/ amount of tracer in GB before stim
HIDA EF in adults < 35% considered abnormal
Is unconjugated bili hydrophobic or hydrophili
- hydrophobic
- circulates bound to albumin preventing toxicity of free (unbound) bilirubin)
how is bilirubin made water solube
-conjugated to glucuronic acid to make water soluble by UDP-glucuronyl transferase (UGT)
How does conjugated bili get into the bile
-secreted into bile by ATP dependent transporter ABCC2/MRP2 on the hepatocyte canalicular membrane
reabsorbed by SI, circulates back into liver and imported into hepatocytes by transport protein OATP1B
What is Rotor Syndrome
-defective hepatocyte “reuptake” of circulating conjugated bili
SLCO1B encoding OATP1B
- Episodic jaundice otherwise Asymptomatic
- histology = normal liver absent OATP1B
- no treatment required
Dubin-Johnson Syndrome
-defective “secretion” of conjugated bili into bile canaliculi
defective ABCC2 gene - encoding ABCC2/MRP2 transporter that couples with ATP hydrolysis to actively pump organic anions into bile canaliculus
- low grade, nonpruritic jaundice; increased in pregnancy and with use of oral contraceptives or other steroid hormones
- jaudice, scleral icterus +/- mild hepatomegaly
Histology: liver black with pigment deposits
Treatment: none necessarily
Gilbert Syndrome
- defect in UGT1A1 - encodes UGT1A1 bilirubin-conjugating enzyme < 50% normal enzyme activity
- Episodic jaundice often during fasting, nonspecific viral illness, poor sleep or physically strenuous activity
Histo: normal liver with decreased UGT staining
Treatment: non necessary -, phenobarb lowers serum bili often to normal levels
Crigler-Najjar
defect in UGT1A encodes UGT1A1 bilirubin-conjugating enzyme- completely absent (type I) or severely reduced (type II)
-Type 1: most severe form: progressive jaundice for first few days of life - high risk of kernicterus
Type II: less severe: lower levels of kernicterus
Histology: normal liver, decrease UGT staining
Treatment:
Type 1 - lifelong phototherapy for 8-12 hrs per day, exchange transfusions to < threshold for kernicterus, consider liver txt
Type II- lifelong phenobarbital thearpy to induce remaining UGT1A! activity (only works for type II). Oral binding agents (cholestyramine, caclium phosphate and agar) to prevent enterohepatic reuptake of bili
What are the most common types of choledocyl cysts
- 5 subtypes
- Most common: type 1 and 4
Type 1: saccular dilatation of extrahepatic duct
Type 4: saccular dilation of intra- and extrahepatic biliary tree
if untreated - risk of cholangiocarcinoma
What is Inspissated bile syndrome
- impaired bile flow= cholestasis
- neonates on chronic TPN or severe intestinal disease at risk
-Urso can improve bile flow
Histological findings of Biliary atresia
- proliferation of bile ducts
- bile plugs of intrahepatic bile ducts
- fibrosis
- cirrhosis
What are the stats for timing and successful Kasai
-bile driainage if portoenterostomy is preformed before
60 days = 70%
60-90 days = 40-50%
90-120 days = 25%
120 days = 10-20%
What is the first line diuretic in ascites managaement
- K sparing diuretics
- often require adding furosemide
What features in a neonate outside of cholestasis would make you think of galacatesomia
- E. coli sepsis
- absent red reflux = cataracts
Key features of Tyrosinemia?
- can present in fulminant liver failure in neonates
- degree of coagulopathy out of proportion of mild increase of liver enzymes
- increased urine succinylacetone is diagnostic
Treatment: NTBC- an inhibitor of an enzyme in the tyrosine degredation pathway
In bile acid synthesis defects what is the level of the serum bile acids
-below normal compared to all other cholestatic diseases
confirm BSAD by fast atom bombardment
-also low GGT
Treat: oral bile acid supplementation
What organ systems are involved in Alagille
- Liver: cholestasis- paucity of bile duts
- Eyes; posterior embryotoxin
- Cardiac: Congenital heart disease with pulmonic stenosis
- Skeletal: butterfly or hemivertebrae
- Renal: common to have renal disease
Features of PFIC 1
FIC1 disease - defect in canalicular surface protein FIC1
- low/normal GGT
- growth failure/diarrhea
- neonatal period or later
Features of PFIC 2
- BSEP (bile salt export pump) mutation - mutation in bile transport into the canaliculus
- low/normal GGT
- pruritis can be severe
- high risk of hepatocellular carcinoma
Features of PFIC 3
-MDR3 deficiency
- mutation in gene coding transporter MDR3 - affecting phosphatidylcholine secretion into bile canaliculus
High GGT
-can present later in life
What are the characteristic findings of PSC on ERCP
- irregular narrowing and stricture of hepatic and common bile ducts
- areas of stenosis diffuse or multifocal
- characteristic “beaded appearance” resulting from areas of stricture with intervening areas of normal or minimally dilated segments
What are the histological findings of PSC
-Fibrous obliteration of small bile ducts with concentric fibrous tissue rings in an “onion skin” appearance
What happens in congenital hepatic fibrosis
- AR disease
- ductal plate malformation of small inter lobular bile ducts
- biliary stricture and periportal fibrosis
- can be associated with ARPKD
- 3 different forms - portal hypertensive, cholangitic, latent
What is the difference btw Caroli disease and syndrome
-congenital disorder resulting in dilation of intrahepatic biliary tree
Disease:
- less common
- sporadic inheritance
- ectasia or segmental dilatin of the large intrahepatic bile ducts
- no other hepatic disease present
Caroli syndrome
- more common
- AR
- biel duct dilation of small or large intrahepatic ducts
- congenital hepatic fibrosis present
- often associated with ARPKD
Liver Biopsy of Caroli syndrome
- show broad bands of fibrosis and distorted, dilated bile ducts often in whorls.
Liver bx findings of Alagilles
- paucity of intrahepatic bile ducts
- 15-20% with periportal and centrilobular fibrosis
- progressive liver disease with fibrosis and cirrhosis in 10-15%
What are the different types of choledochal cysts
Type 1: Cystic dilation of CBD - 90%
A: large saccular cystic dilation
B: small localized segmental dilation
C: diffuse cylindric fusiform dilation
Type 2: diverticulum of CBD and/or GB
Type 3: Choledochocele (intraduoadenal)
Type 4: Multiple cysts
A: cysts both intral and extra hepatic
B: isolated extrahepatic
What is the treatment for choledochal cyst
- Complete surgical resection of cyst with a Roux-en-Y choledochojejunostomy proximal to the mist distal lesion
- risk of malignancy in residual cyst tissue and increases with age - adenocarcinoma of bile duct or GB most common
Pathophysiology behind pruritus in cholestasis
thought to be mediated by opioid neuttransmission
- opioid peptides = mast cells to release histamine
- exogenous opiods cause pruritis relieved by only opiod antagonists
- cirrhotic adults of increase endogenous opioids such as enkephalins
- opioid antagonists in cholestatic individuals may cause a withdarwal response simialr to opiod abusers
Medications for Pruritis
-diphenhydramine
-hydorxyzine
-UDCA
-Cholestyramine
-Rifampin
Naloxon and naltrexone
How do antihistamines prevent itching
- block H1-receptors on peripheral noiceptors = decrease sensation and itching
- compete with histamine for H1-receptor sites
How does UDCA work
- hydrophilic bile acids stimulates hepatic bile production and protects hepatocytes against cytotoxicity by hydrophilic bile acids
- reduces toxicity of endogenous bile acids but competitively inhibiting intestinal absorption
How does cholestyramine work
-binds bile acids in intestine forming nonabsorable complex, preventing enterohepatic reuptake of bile salts
UDCA not effective in dissolving radio-opaque stones, bile pigment stones and calcified cholesterol stones
How does naloxone and naltrexone work
-bind competitively with opioid receptors with high affinity but without activating receptors
Where is AST found outside of the liver
- heart muscle
- skeletal muscle
- kidney
- brain
- pancreas
- lung
- leukocyte
- RBCs
Where is ALP found outside the liver
- bone
- placenta
- intestine
- WBCs
What is low ALP suggestive of
- zinc deficiency
- Wilsons disease
Where is GGT found outside of the liver
- kidney
- pancreas
- spleen
- brain
- breas
- small intestine
What is the half life of Albumin
-20 days
AST:ALT ratios suggestive of
a) NASH
b) ETOH liver disease
c) Fulminant wilsons
a) <1 : NASH
b) > 2: ETOH liver disease
c) > 4: fulminant wilson disease
DDX for increase transaminase in post liver txt pt
- acute/chronic rejection
- AIH
- infection
- biliary complications
- vascular complications
What are the 5 mechanisms of hepatomegaly
- inflammation
- excessive storage
- infiltration
- congestion
- obstruction
What is the definition of portal pressure
-portal pressure > 10 mmHg
OR
-HVPG > 5mmHg
How does PHTN affect circulation
- results in hyperdynamic circulation with:
- increased cardiac output
- decreased splanchnic tone
- decreased splanchic vasconstrictor responsiveness
- leads to vasodilation = Na retention and increased vascular volume due to renal response to vasodilation
Prehepatic causes of PHTN
- PV thrombosis
- AV fistula
- Splenic vein thrombosis
- Congenital stenosis or external compression of the PV
Posthepatic causes of PHTN
- Budd-chiari
- congestive heart failure
- constrictive pericarditis
- inferior vena cava obstruction
What type of hepatic flow indicates worse PHTN
-heaptofugal flow - flow away from the liver
What is the HVPG
- Hepatic venous pressure gradient
- difference between wedge hepatic venous pressure (indicates PV pressure) and free hepatic venous pressure
What HVPG is associated with
1) Varices
2) Variceal bleed/ascities
1) HVPG > 10
2) HVPG > 12
What cause a variceal to bleed
-when the wall tension exceeds the variceal wall strength
Definition of Hepatopulmonary syndrome
-oxygen partial pressure < 70 mm Hg
OR
-increase in alveolar-arterial oxygen gradient > 15 mm Hg
What is portopulmonary hypertension
-Pulmonary artery HTN in pt with PHTN
- fatigue, chest pain, syncope and dyspnea with activity
- tricupsid reurge
How does octreotide work in variceal bleed
-decreases splanchnic flow which decreased PV inflow and decreases PV pressure
How do you treat gastric varices
- endoscopic variceal obturation with cyanoacrylate is first line therapy for gastric variceal bleed
- Balloon-occluded retrodgrade transveous obliteration eliminates gastric varices in the fundus
Indication for surgical management of varices
- extrahepatic PV thrombosis
- variceal bleed refractory to medical/endoscopic management and does not meet criteria for transplantation
- refractory ascities
- complications due to hypersplenism (severe pain, plts < 10000, recurrent infections)
- medical refractory portosystemic encephalopathy
What is a mesorex shunt
- mesenteric left PV bypass
- 1st opt for pts with extrhepatic PV thrombosis - must have normal liver architecture
-jugular venous autograft to shunt blood from superior mesenteric vein into intrahepatic PV
restores hepatopetal flow, decompreses varices, improves spleen size
What is a distal splenorenal shunt
- decompresses esophageal and gastric varices through the short gastric vein, spleen and splenic vein to the left renal vein
- lower risk of portosystemic encephalopathy than mesocaval shunt
What is TIPS
- communication between hepatic and PV
- decreases portal pressure
- recurrent variceal bleeding not responsive to medical/endoscopic therapy, refractory ascities, Budd-chiari syndrome, VOD, HRS, HPS
- can use as bridge to transplant
Complications of TIPS
- encephalopathy
- PV leakage
- restenosis
- peforation
- infection
- hemolysis
What factors lead to ascites development in cirrhosis
- splanchnic vasodilation
- hyperadosteronism
- PHTN
- disturbed hydrostatic and oncotic forces that regulate splanchnic portal and hepatic blood and lymphatic flow
- increased Na retention via RAS system and secretion of antidiuretic hormone
- Na retention = expansion of extracellular volume and accumulation of ascities
- PHTN contributes to increased splanchnic capillary pressure = excessive lymph formation
What is the SSAG
- serum ascites albumin gradient
- difference between serum and ascitic fluid albumin
SAAG < 11 = not PHTN as cause fo ascites
What are treatment strategies for ascites
Strategies focus on mobilizing intraperitoneal fluid and correcting the relative systemic hypovolemia
- Na restriction
- Diuresis:
a. spironolactone: counters hyperaldosterone. Competitive inhibitor of aldosterone at distal renal tubules: increase Na, CL and H2O excretion and conserve K and H
b. Loop diuretic: directly inhibits reabsorption of Na and Cl in the ascending loop of Henle and distal renal tubules; excretion of Mg, Na, Cl, H2O and Ca - Fluid restrictionp
- IV albumin
- Paracentesis
- Surgical management: shunts
Definition of Acute Liver Failure
- biochemical evidence of injury to the liver
- no history of known chronic liver disease
- Coagulopathy not corrected by vit K
- INR > 1.5 if the pt has HE or > 2 if the pt does not have HE
Features of tyrosinemia
-profound coagulopathy and normal or near normal serum aminotransferase
Factors that play a central role in the pathogenesis of HE
- hyperammonemia: - associated with increase levels of glutamine in astrocytes = cell swelling
- increased central blood flow may contribute to the development of cerebral edema
- enhanced inflammatory response and inflammatory cytokines such as TNFalpha
What is the histology of CMV liver infection
-large intranuclear inclusion bodies in bile duct epithelium and occasionally in hepatocytes or kupffer cells and intracytoplasmic inclusion bodies in hepatocytes
Treat with gancyclovir or foscarnet
Histology of HSV liver bx
-necrosis with characteristic intranuclear acidophilic inclusions in hepatocytes and multinucleated giant cells
What are the two different forms of Acute Hep D infection
- coinfection: simultaneous acquisition of HBV and HDV
- superinfection:
Perihepatitis (Fitz-Hugh-Curtis syndrome)
- Associated with salpingitis/history of pelvic inflammatory disease
- infection from genital tract or hematologic spread
- “violin string” adhesions between hepatic capsule, abdominal wall and diaphragm
- hemorrhagic spots and white fibrous plaques on liver surface