Textbook of Diagnostic Sonography - Chapter 9 Liver - Pathology of the Liver Including Developmental Anomalies and Hepatic Vascular Flow Abnormalities

congenital diaphragmatic hernia

Diaphragm doesn't fully develop allowing abdominal organs (varying amounts of liver tissue) to migrate into the chest cavity

Differential Considerations for Portal Venous Hypertension

Occlusion of vessels

When acute or chronic hepatocellular disease blocks the flow of blood throughout the liver, what happens?

blood backs up into the hepatic portal circulation, causing the blood pressure in the hepatic circulation to increase, resulting in portal hypertension

Constrictive pericarditis or other right-sided heart failure over time will cause

centrilobular fibrosis, hepatic regeneration, and cirrhosis - all leading to subsequent portal hypertension

In portal hypertension, the most common mechanism for increased resistance to flow occurs in patients with

cirrhosis

what disease process produces areas of micronodular and macronodular regeneration, atrophy, and fatty infiltration, which makes it difficult for the blood to perfuse?

cirrhosis

What hepatocellular diseases may be detected with ultrasound examination?

cirrhosis acites fatty liver

sonographic findings of portal venous hypertension

collateral circulation/reversal of flow ascites hepatosplenomegaly

Primary Budd-Chiari syndrome

congenital obstruction of hepatic veins or IVC by membranous webs across upper vena cava at or just above entrance of left and middle hepatic veins. most common in asia

vascular anomalies

developmental anomaly -includes variations of hepatic artery as it arises from celiac axis. 45% of patients may have a hepatic artery variation: 1. replaced left hepatic artery originating from left gastric artery, 2. replaced right hepatic artery originating from SMA, 3. replaced common hepatic artery originating from SMA - Variations in portal venous anatomy are uncommon, but include atresias, strictures, and obstructing valves -Variations in branching of hepatic veins are common. Most common when accessory vein drains superoanteior segment of right lobe. It may empty into middle hepatic vein or join right hepatic vein.

Agenesis

developmental anomaly -incompatible with life -when this anomaly occurs in the right, left, or caudate lobes, hypertrophy of the other lobes occurs

Anomalies of Position

developmental anomaly -situs inversus (organs are reversed with liver on left and spleen on the right) -congenital diaphragmatic hernia or omphalocele (varying amounts of liver tissue may herniate into thorax or outside abdominal cavity).

accessory fissures

developmental anomaly -true accessory fissures are uncommon. caused by infolding of peritoneum

collateral circulation

develops when normal venous channels become obstructed. the diverted flow causes embryologic channesl to reopen; blood flows hepatofugally (away from liver) and is diverted into collateral vessels

Ultrasound findings of portal hypertension

dilation of the portal, splenic, and mesenteric veins; reversal of portal venous blood flow; and development of collateral vessels (patent umbilical vein, gastric varices, splenorenal shunting)

Collateral channels of circulation

gastric veins (coronary veins) esophageal veins recanalized umbilical vein splenorenal veins gastrorenal veins retroperitoneal veins hemorrhoidal veins intestinal veins

what portal vein diameter has been associated with portal hypertension?

greater than 13 mm

Portal hypertension: -splenic vein pressure of

greater than 15 mm Hg

Portal hypertension: -portal vein pressure of

greater than 30 cm H20

clinical findings in portal venous hypertension

increased liver enzymes -gastrointestinal bleeding -jaundice -hematemesis

portal hypertension may develop along two pathways. One entails increased resistance to flow. The other entails...

increased portal blood flow

Cirrhosis is the most common cause of

intrahepatic portal hypertension

Transjugular intrahepatic portosystemic shunt (TIPS)

intrahepatic shunts created percutaneously with use of metallic expandable stents

portal hypertension that develops along the pathway involving increased resistance to flow is found in patients with

liver disease or diseases of the cardivascular system

Portal Hypertension: -Hepatic venous gradient is

more than 5 mm Hg

differential consideration for portal venous hypertension

occlusion of vessels

Portal vein compression or thrombosis is an indication for

portal hypertension

acute onset of congestive heart failure w/tricuspid regurgitation is an indication of

portal hypertension

acute onset of constrictive pericarditis is an indication for

portal hypertension

acute onset of hepatic vein occlusion (Budd-Chiari syndrome) is an indication for

portal hypertension

congenital, traumatic, or neoplastic arterioportal fistula is an indication of

portal hypertension

when hepatopetal flow (toward liver) is impeded by thrombus or tumor invasion, what may develop?

portal hypertension

How is portal hypertension divided and what does it depend on?

presinusoidal (hepatic vein wedged pressure is normal) intrahepatic (hepatic vein wedged pressure is elevated)

situs inversus

reversed position of organs - liver L, spleen R

If portal hypertension becomes extensive, the portal system can be decompressed by

shunting blood to the system venous system via portacaval shunts

Evaluation of the liver parenchyma includes assessment of

size configuration homogeneity contour

Liver volume can be determined from serial scans in an effort to detect

subtle increases in size or hepatomegaly

What causes extrahepatic portal hypertension?

the development of increased pressure in the portal-splenic venous system

Secondary Budd-Chiari Syndrome

thrombosis in hepatic veins or IVC occurs in patients with predisposing conditions: *prolonged oral contraceptive use, *pregnancy tumors (hepatocellular carcinoma, renal cell carcinoma, adrenal carcinoma, leiomyosarcoma of the IVC) *infections *trauma 25%-30% unknown cause

Sonographic findings in portal venous hypertension

-collateral circulation/reversal of flow -ascites -hepatosplenomegaly

Major sites of portosystemic venous collaterals

-gastroesophageal junction located between coronary and short gastric veins and systemic esophageal veins -paraumbilical vein runs in the falciform ligament and connects l. portal vein to systemic epigastric veins near umbilicus -splenorenal and gastrorenal veins -intestinal veins -hemorrhoidal veins

Clinical findings in portal venous hypertension

-increased liver enzymes -gastrointestinal bleeding -jaundice -hematemesis

sonographic protocol of portal hypertension includes:

-perform routine abdominal imaging protocol -assess for presence of ascites -obtain diameter measurements of splenic and main portal veins on inspiration and expiration -assess for presence of collateral blood vessels (splenic hilum, porta hepatis, umbilical vein) -determine flow direction of portal veins (main, left, and right) and splenic and SM veins -assess for presence of splenorenal shunting -assess for patency of umbilical vein -determine patency and direction of flow in IVC and hepatic veins -assess and document patency of surgically placed shunts

Indications for Portal Hypertension

-suspected portal hypertension secondary to liver disease -portal vein compression or thrombosis -acute onset of hepatic vein occlusion (Budd-Chiari syndrome), constrictive pericarditis, or congestive heart failure with tricuspid regurgitation -congenital, traumatic, or neoplastic arterioportal fistula

splenorenal shunt

Attaches the splenic vein to the left renal vein

Portal hypertension: -A wedged hepatic vein pressure or direct portal vein pressure of more than

5 mm Hg greater than the IVC pressure

Clinical symptoms of portal hypertension secondary to portal vein thrombosis are very different from those of intrahepatic disease. What is the primary complaint?

Ascites No jaundice No tender enlarged liver Splenomegaly and bleding varices may be present

portacaval shunt

Attaches the main portal vein at the superior mesenteric vein-splenic vein confluence to the anterior aspect of the inferior vena cava.

mesocaval shunt

Attaches the mid-distal superior mesenteric vein to the inferior vena cava May be difficult to image if overlying bowel gas is present

Extensive hepatic vein occlusion that can occur with this condition is usually fatal within weeks or months at the onset of symptomsf

Budd-Chiari syndrome

what causes intrahepatic portal hypertension?

It is the result of diseases that affect the portal zones of the liver like primary biliary cirrhosis, schistosomiasis, congenital hepatic fibrosis, or toxic drugs ***Cirrhosis is the most common cause.*** Diffuse metastatic liver disease, thrombotic diseases of IVC and hepatic veins, constrictive pericarditis or other right-sided heart failure over time will cause centrilobular fibrosis, hepatic regeneration, and cirrhosis, all leading to portal hypertension May also develop when hepatopetal flow (toward the liver) is impeded by thrombus or tumor invasion

associated with cirrhosis, hepatic vein thrombosis, portal vein thrombosis, and thrombosis of the IVC

Portal Hypertension

Is the inferior accessory hepatic fissure a true accessory fissure?

Yes. It stretches inferiorly from the right portal vein to the inferior surface of the right lobe of the liver.

Portal hypertension: -portal venous pressure

above 10 mm Hg

developmental anomalies

agenesis, anomalies of position, accessory fissures, and vascular anomalies

portal hypertension that develops along the pathway involving increased portal blood flow is found in patients that may have

an arteriovenous fistula or splenomegaly secondary to a hematologic disorder

where do collateral veins most frequently occur?

area of the esophagus, stomach, and rectum. rupture of these can cause massive bleeding/death

the most definitive way to diagnose portal hypertension

arteriography

most characteristic clinical feature of budd-chiari syndrome

ascites

The more common form of Budd-Chiari syndrom is the chronic form in which patients...

have a vague illness and abdominal distress weeks or months in duration, followed by ascites and hepatomegaly. -jaundice is mild or absent -spleen becomes palpable as portal hypertension increases -when thrombus is found in the IVC - edmea of legs is gross and there is venous distention over the abdomen, flanks, and back. Albuminuria may be found.

Hepatocellular disease affects

hepatocytes and interferes with liver function enzymes

in portal hypertension, the sonographer should search for

hepatofugal flow in the portal vein

omphalocele

herniation at the umbilicus (a part of the intestine protrudes through the abdominal wall at birth) varying parts of liver may herniate outside of abdominal cavity

why are collateral veins formed?

in an effort to relieve the pressure of portal hypertension, these veins are formed that connect to the systemic veins. known as varicose veins

Portal Hypertension

increase in portal venous pressure or hepatic venous gradient exists when portal venous pressure is above 10 m Hg or hepatic venous gradient is more than 5 mm Hg caused by increased resistance to venous flow through the liver

Budd-Chiari syndrome

thrombosis of the hepatic veins or IVC. uncommon, dramatic illness characterized by abdominal pain, massive ascites, and hepatomegaly other symptoms include: jaundice, vomiting, diarrhea may present acutely (rare) or as a chronic illness (common)

the most common collateral pathways

through the coronary and esophageal veins - as occur in 80%-90% of patients with portal hypertension

why is sonography useful in patients with portal hypertension?

to define presence of ascites, hepatosplenomegaly, and collateral circulation; the cause of jaundice; and the patency of hepatic vascular channels

Portal vein thrombosis may develop secondary to

trauma sepsis cirrhosis hepatoceullar carcinoma -definitive diagnosis made w/liver biopsy and positive findings of portal hypertension

the TIPS is evaluated for patency how?

using the liver as an acoustic window to image the flow velocity pattern

what may develop due to increased pressure in the portal vein, usually secondary to cirrhosis?

varices - tortuous dilations of veins bleeding from the varices occurs with increased pressure