Sinusoidal obstruction syndrome overview

Sinusoidal obstruction syndrome Microchapters
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

Historical Perspective

Hepatic veno-occlusive disease or sinusoidal obstruction syndrome was first described in 1905 as endophelibitis of the terminal hepatic veins. Ionizing radiations as a cause of sinusoidal obstruction syndrome was identified in the 1960's and bone marrow transplant in the 1970's. However, sinusoidal obstruction syndrome or hepatic veno-occlusive disease was a well-established concept by the mid-1960's.

Classification

There is no established system for the classification of sinusoidal obstruction syndrome. However, it can be classified on the basis of severity as mild, moderate and severe.

Pathophysiology

In the BMT setting, VOD is felt to be due to injury to the hepatic venous endothelium from the conditioning regimen.

Toxic agents causing veno-occlusive disease include plants as well as the medication cyclophosphamide.

Natural History, Complications, and Prognosis

Prognosis

When associated with bone marrow transplant, VOD is fatal in over 30% of cases. Cases due to plant alkaloids often have a longer and more unpredictable course.

Diagnosis

Physical Examination

Features of VOD include weight gain, tender hepatomegaly, ascites, and increased bilirubin. It often is associated with renal failure.

Diagnosic Criteria

Imaging Findings

Ultrasound

Hepatic doppler ultrasound is typically utilized to confirm or suggest the diagnosis. Most common findings on liver doppler ultrasound include increased phasicity of portal veins with eventual development of portal flow reversal. The liver is usually enlarged but maintained normal echogenicity. A liver biopsy is required for a definitive diagnosis.

Treatment

Medical Therapy

Treatment for VOD is primarily supportive. In the BMT setting, defibrotide is an investigational treatment that may be promising. Defibrotide is a polydeoxyribonucleotide isolated from pig intestine. Although its mechanism of action in VOD is unclear, the drug is believed to have antithrombotic properties. In August 2009, Gentium S.p.A., which sponsored the phase 3 clinical trial (pivotal) of defibrotide in hepatic VOD, announced disappointing results. Further clinical development of defibrotide for this indication is uncertain.

See also

• Budd-Chiari syndrome (large liver vein obstruction due to thrombosis)