From the Department of Radiology, Baylor University Medical Center, Dallas, Texas.

Corresponding author: Joseph A. Kuhn, MD, Department of Radiology, Baylor University Medical Center, 3500 Gaston Avenue, Dallas, Texas 75246.

DIAGNOSIS: Budd-Chiari syndrome (BCS) secondary to paroxysmal nocturnal hemoglobulinuria.

DISCUSSION

BCS is a rare, life-threatening disorder caused by hepatic venous outflow obstruction. The obstruction may occur at any level from the hepatic lobule efferent vein to the junction of the inferior vena cava with the right atrium. Classic BCS results from obstruction of the 3 major hepatic veins or the inferior vena cava. Liver failure and portal hypertension ensue regardless of the cause or level of obstruction.

BCS has been associated with multiple etiologies; however, many cases are idiopathic. Primary BCS is caused by membranous (or web) obstruction of the suprahepatic inferior vena cava. Congenital webs are more common in Asian and South African populations; this is a relatively rare cause of BCS in the USA. Webs or membranes may also form in adult populations, and there is some evidence that these membranes are acquired lesions from an organized thrombus of the inferior vena cava (1).

Secondary BCS results from obstruction of the hepatic veins or the inferior vena cava by thrombus or tumor. In most cases of thrombotic occlusion, a hypercoagulable state is present (1-3). Pregnancy, eclampsia, the postpartum state, and oral contraceptive use increase the risk of thrombus formation in women. Blunt abdominal trauma and subsequent vessel wall injury may also predispose to thrombus formation. Tumor thrombosis occurs in hepatocellular carcinoma, renal cell carcinoma, and adrenal carcinoma and rarely with primary leiomyosarcoma of the inferior vena cava. Space-occupying lesions such as tumors, cysts, and abscesses may also obstruct outflow by extrinsic compression of the major venous structures.

The classic syndrome consists of ascites, hepatomegaly, and abdominal pain. The acute presentation is often fulminant hepatic failure, encephalopathy, severe coagulopathy, and rapid death. The chronic form of BCS is much more common. Abdominal pain may be secondary to ascites or distention of Glisson's capsule by hepatic congestion. Nausea, vomiting, and diarrhea may be present in either the acute or chronic form of the disease. Jaundice is typically mild or absent. Wasting and signs and symptoms of portal hypertension are more common in the chronic disease state. If the inferior vena cava is obstructed, leg edema and venous distention of the trunk will occur.

Routine laboratory studies are often of little value in diagnosing BCS. There may be mild elevation of serum transaminases, bilirubin, and alkaline phosphatase, which merely indicates hepatic dysfunction. Serum albumin is commonly low. Evaluation of the ascitic fluid typically reveals a high albumin content. Liver biopsy shows zone 3 congestion and is important in determining the degree of fibrosis and cirrhosis (1).

Ultrasound is the best modality for initially evaluating patients with suspected BCS. Pulsed and color flow Doppler sonography allow for direct, noninvasive evaluation of the venous structures. The presence of collateral circulation pathways and patency and direction of portal venous flow should be determined. Demonstration of intrahepatic or capsular collateral pathways is pathognomonic for BCS (3). Ascites, caudate lobe enlargement, and changes of the hepatic echotexture are also defined by ultrasound.

CT and magnetic resonance imaging (MRI) are also useful in evaluating the liver in BCS. Both will demonstrate hepatomegaly in the acute syndrome and caudate lobe enlargement in the chronic disease. Diffuse hypodensity of the hepatic parenchyma is seen on noncontrast CT. Patchy central enhancement with a nonenhancing peripheral zone of tissue is the classic enhancement pattern seen on contrast-enhanced CT (Figure 1). Additionally, the hepatic veins may not be visualized or thrombus may be directly visualized (Figure 1). MRI provides essential flow information and can determine the presence of collateral circulation. Collaterals appear as comma-shaped varices (3). The hepatic parenchyma is typically heterogeneous on MRI evaluation (Figure 2).

Angiography is the gold standard for defining the location and extent of occlusion in BCS (3). Inferior venacavography and hepatic venography demonstrate patency of these vessels. The pathognomonic finding of BCS is the presence of spider web collaterals (Figure 5). Additionally, wedge pressures may be obtained during angiography.

The etiology, degree of occlusion, and presence of collaterals determine the clinical course of BCS. If the disease is untreated, death will occur in months to years. Medical management including diuretics and anticoagulants is rarely effective. Regional and systemic thrombolytics have also been utilized. Direct treatment with balloon angioplasty of a short-segment stenosis, occlusion, or web can restore physiologic hepatic venous drainage. Other therapeutic options include stenting, laser treatment, transcardiac membranotomy, or membrane excision (2). Surgical portosystemic shunting reduces high intrahepatic pressures, providing an outflow tract. The transjugular intrahepatic portosystemic shunt procedure has recently been utilized. Finally, liver transplantation is advocated in patients with acute BCS, those with end-stage liver disease, and those who rapidly deteriorate after more conservative treatment options have been implemented (2).

1. Sherlock S. Diseases of the Liver and Biliary System, 8th ed. Oxford: Blackwell Scientific Publications, 1989:212-220.
2. Tilanus HW. Budd-Chiari syndrome. Br J Surg 1995;82:1023-1030.
3. Hahn PF, Yucel EK. Imaging of Budd-Chiari syndrome. In Ferrucci JT, Stark DD, eds. Liver Imaging. Reading: Andover Medical Publishers, 1990:260-268.