Sinusoidal obstruction syndrome overview
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Differentiating Sinusoidal obstruction syndrome from Other Diseases |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Overview
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
The development of sinusoidal obstruction syndrome begins with the injury to hepatic venous endothelium. It is thought that preexisting liver disease increases the risk of developing sinusoidal obstruction syndrome (SOS) due to impairment of drug metabolism which predisposes to the endothelial injury. The endothelial cells in patients with hepatitis may have abnormal expression of adhesion molecules and procoagulant factors. The deposition of fibrinogen and factor VIII within the sinusoids leads to their dilation and congestion by erythrocytes. The progressive occlusion of venules leads to widespread zonal liver disruption and centrilobular hemorrhagic necrosis. Hepatic sinusoidal obstruction syndrome (SOS) is mainly seen in patients of hematopoietic cell transplantation.
Causes
The most common cause of sinusoidal obstruction syndrome is hematopoietic cell transplantation. Other less common causes include chemotherapeutic agents and pyrrolizidine alkaloids.
Differentiating Sinusoidal obstruction syndrome from Other Diseases
The differential diagnosis of sinusoidal obstruction syndrome includes other causes of hepatic failure that may have abnormal liver function tests such as increased conjugated bilirubin and alkaline phosphatase or a clinical presentation as right upper quadrant abdominal pain, jaundice or ascites.
Epidemiology and Demographics
The incidence of sinusoidal obstruction syndrome depends on the presence of risk factors, chemotherapy regimen and the clinical criteria used for the diagnosis. The incidence after allogeneic hematopoietic cell transplant ranges from a low of 10,000 persons per 100,000 persons to a high of 15,000 persons per 100,000 persons. The incidence of sinusoidal obstruction syndrome after autologous hematopoietic cell transplant is below 5,000 persons per 100,000 persons.
Risk Factors
Common risk factors in the development of sinusoidal obstruction syndrome are stem cell transplantation, preexisting liver dysfunction and high-dose conditioning regimens.
Screening
Natural History, Complications, and Prognosis
Natural History
Complications
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
History and Symptoms
Physical Examination
Features of VOD include weight gain, tender hepatomegaly, ascites, and increased bilirubin. It often is associated with renal failure.
Laboratory Findings
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.
Other Diagnostic Studies
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.
Surgery
Prevention
See also
- Budd-Chiari syndrome (large liver vein obstruction due to thrombosis)