Portal Hypertension and Varices

Published on 13/07/2015 by admin

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Last modified 13/07/2015

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 Ascites: Fluid in dependent recesses of peritoneal cavity

image Splenomegaly: Spleen is enlarged > 500 cc
image Varices: Well-defined, tubular or serpentine collateral vessels with same enhancement as adjacent veins

– Usually opacify on venous phase (not arterial phase)
image Mesenteric edema: ↑ attenuation of mesenteric fat
image Dilation of mesenteric veins : Portal vein > 13 mm
image Slow or reversed flow in portal veins on ultrasound

– Slow flow in portal vein (< 15 cm/sec)
– Portal flow may be biphasic or completely reversed
– ↑ risk of portal vein thrombosis
image Portal gastropathy, enteropathy, and colopathy

– May manifest as thickening of colon (especially right colon), small bowel, and stomach
image Gallbladder wall thickening

PATHOLOGY

• Causes of portal hypertension divided into 3 categories

image Pre sinusoidal: Portal vein/splenic vein thrombosis
image Sinusoidal: Cirrhosis (most common), extensive hepatic tumor, or any severe hepatocellular disorder
image Post sinusoidal: Right-sided heart failure, constrictive pericarditis, Budd-Chiari syndrome
• Varices (portosystemic collaterals) develop when portal pressures increase beyond critical value

image Blood in portal venous system bypasses liver and empties into systemic veins via portosystemic collaterals

CLINICAL ISSUES

• Asymptomatic until varices rupture or ascites are infected
• 30% of patients with esophageal varices experience variceal hemorrhage within 2 years of diagnosis
• Many patients with cirrhotic ascites develop spontaneous bacterial (or rarely tuberculous) peritonitis
image
(Left) Graphic shows esophageal varices image as serpiginous, longitudinally oriented submucosal venous collaterals extending into the gastric fundus.

image
(Right) Esophagram performed after endoscopic sclerosis of varices shows defects image in the esophageal wall. Varices are usually pliable and easily compressed. Varicoid carcinoma could have a similar appearance.
image
(Left) Coronal CECT demonstrates multiple varices image in the left upper quadrant in communication with the splenic vein and the left renal vein image, which appears dilated, forming a splenorenal shunt.

image
(Right) Coronal CECT in a patient with cirrhosis and portal hypertension demonstrates thrombus image in the portal and superior mesenteric veins, with calcification suggesting chronicity. Portal hypertension increases the risk of portal vein thrombus due to stasis and slow flow.

TERMINOLOGY

Definitions

• Portal hypertension: Elevated portal pressures due to resistance to portal flow, defined as absolute portal venous pressure of > 10 mm Hg or gradient between portal and systemic veins of > 5 mm Hg
• Varices: Abnormally dilated and tortuous veins due to rerouting of blood flow away from liver into lower pressure systemic veins through collateral pathways
• Ascites: Pathologic fluid accumulation in peritoneal cavity

IMAGING

General Features

• Best diagnostic clue
• Location

image Ascites: Dependent recesses of peritoneal cavity
• Common features of portal hypertension

image Ascites: Water density fluid in dependent recesses of peritoneal cavity
image Splenomegaly: Spleen is enlarged > 500 cc

– CT or US can estimate or calculate splenic volume
– Usual upper limits: 13 cm in length and 6 × 8 cm in width and breadth, respectively
image Varices: Well-defined, tubular or serpentine portosystemic collateral vessels with same enhancement as adjacent veins

– Usually opacify on venous phase images (not on arterial phase)
image Mesenteric edema: Stranding and increased attenuation in mesenteric fat
image Dilation of mesenteric veins (portal vein, superior mesenteric vein, and splenic vein)

– Portal vein is often dilated > 13 mm
image Slow or reversed flow in portal veins on Doppler ultrasound

– Normal portal vein flow is hepatopetal (toward liver) with normal flow velocity of 15-40 cm/sec
– As portal hypertension progresses, portal blood flow velocities decrease
– Eventually, portal flow may be biphasic (alternating hepatopetal/hepatofugal flow) or completely reversed
– Stasis of blood flow in portal vein as well as hypercoagulability due to intrinsic liver disease increases risk of portal vein thrombosis
image Portal gastropathy, enteropathy, and colopathy

– May manifest as thickening of colon (especially right colon), small bowel, and stomach
image Gallbladder wall thickening: Due to combination of portal hypertension, hepatocellular dysfunction, and hypoproteinemia
• Varices: Types or locations

image Left gastric venous collateral vessels

– Vascular channels in triangular fatty tissue between medial wall of upper gastric body and posterior margin of left hepatic lobe in lesser omentum
– Coronary (left gastric) vein ≥ 5-6 mm in diameter is considered abnormal
– Usually accompanied by esophageal or paraesophageal varices
image Esophageal varices

– Dilated tortuous submucosal venous plexus of esophagus can be divided into “uphill” and “downhill” varices

image Uphill varices (collateral blood flow into superior vena cava (SVC) from portal vein via azygous vein): Result from portal hypertension and found in distal 1/2 of esophagus
image Downhill varices (collateral flow from SVC into inferior vena cava [IVC] or portal system): Usually due to SVC obstruction and found in proximal 1/3 of esophagus
– Tortuous or serpiginous longitudinal filling defects on esophagography

image Varices may collapse during esophageal peristalsis or with distention of lumen
image Best detected when esophagus is collapsed and esophageal mucosa coated with thick barium
– CECT has limited sensitivity for small esophageal varices, which may not be evident when collapsed

image Can be simulated or hidden by esophagitis or hiatal hernia
– Endoscopy is most sensitive diagnostic tool
– Most clinically significant varices due to risk of bleeding
image Paraesophageal varices

– Collateral vessels in posterior mediastinum behind esophageal wall connect coronary vein with azygos and hemiazygos veins and vertebral plexus
– Can mimic posterior mediastinal mass on chest x-ray
image Recanalized paraumbilical vein

– Dilated collateral vein (≥ 3 mm) arising from left portal vein and coursing between medial and lateral segments of left hepatic lobe in anterior edge of falciform ligament
– Presence is virtually diagnostic of portal hypertension
image Abdominal wall varices

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