Portal hypertension is defined as a hepatic venous pressure gradient (HVPG) >5 mmHg, which is a surrogate for the portosystemic pressure gradient. Clinically significant portal hypertension is defined as a gradient >10 mmHg, and variceal bleeding may occur at a gradient >12 mmHg. 

Pathology

Etiology

Causes can be split by their relation to the hepatic sinusoids ⁷:

Prehepatic causes

• portal vein thrombosis

• extrinsic compression of portal vein

• congenital portal vein stenosis

• arteriovenous fistula

• SVC obstruction (downhill varices)

Hepatic/sinusoidal causes

• cirrhosis

• viral hepatitis

• schistosomiasis (S. mansoni or S. japonicum)

• congenital hepatic fibrosis

• infiltrative liver diseases

• polycystic liver disease

• nodular regenerative hyperplasia

• idiopathic portal hypertension

Posthepatic causes

• Budd-Chiari syndrome

• sinusoidal obstruction syndrome

• congestive cardiac failure

• constrictive pericarditis

Subtypes

• sinistral portal hypertension ⁵

Radiographic features

Ultrasound

• dilated portal vein (>13 mm): non-specific as an isolated finding ¹⁰

• decreased portal vein velocity <16 cm/sec ¹⁰

  • if recanalized paraumbilical vein, velocity may be increased ⁹

• pulsatile portal waveform as pressure increases ^9,10

• biphasic or reverse flow in the portal vein (late stage): pathognomonic ¹¹

• portal-systemic collateral pathways: varices (e.g. paraumbilical, splenorenal) are considered pathognomonic ¹¹

• splenomegaly

• ascites

• cause of portal hypertension often identified, most commonly cirrhosis

CT and MRI

• dilated portal vein +/- mesenteric veins

• contrast enhancement of the paraumbilical vein: pathognomonic ^ref

• portosystemic collaterals ⁴

• splenomegaly

• ascites

• cause of portal hypertension can often be identified

Treatment and prognosis

Management ultimately depends on the underlying etiology and the associated complications. Generally, management options include:

• lifestyle modifications: dietary sodium restriction (e.g. for ascites)

• medications: propranolol (e.g. for varices), diuretics (e.g. for ascites)

• interventional procedures

  • creation of shunts: transjugular intrahepatic portosystemic shunt (TIPS), surgical portosystemic shunt, surgical splenorenal shunt 

  • balloon dilatation of hepatic vein (e.g. for thrombosis/web in hepatic vein)

  • transhepatic clot thrombolysis (e.g. for portal vein thrombosis)

  • splenic artery embolization ³

  • liver transplantation

Complications

• ascites

• esophageal varices and gastric varices

  • variceal bleeding (30-50% mortality with each bleed)

• portal hypertensive gastropathy/enteropathy/colopathy

• hepatic encephalopathy

• hepatorenal syndrome

• hepatopulmonary syndrome

• congestive splenomegaly and hypersplenism

Differential diagnosis

Dilatation of splenic veins at the splenic hilum without splenomegaly may occur in situations such as a state of increased perfusion of splenic tissue associated with an immune response ⁶.