venoocclusive

Venoocclusive, often written veno-occlusive, is an adjective used in medicine to describe processes or conditions that involve occlusion of a vein or venous outflow. It is most commonly encountered in reference to veno-occlusive disease (VOD), a pathologic sequence in which small veins or hepatic sinusoids become obstructed, leading to impaired venous drainage and tissue congestion.

The most well-known form is veno-occlusive disease of the liver, also called sinusoidal obstruction syndrome. It frequently occurs after high-dose chemotherapy or hematopoietic stem cell transplantation. Clinically it presents with hepatomegaly, weight gain, right upper quadrant pain, jaundice, and ascites; in severe cases it can progress to liver failure and multi-organ dysfunction. Pathophysiology involves injury to the endothelium, swelling, inflammation, and intravascular fibrin deposition that narrows or blocks venous outflow.

Outside the liver, venous occlusion describes other conditions in which venous drainage is impeded, such as retinal vein occlusion in ophthalmology, or other tissue-specific venous occlusive processes. The unifying feature is disruption of venous outflow that leads to edema, hypoxia, and organ dysfunction.

Diagnosis is based on clinical presentation and is supported by imaging and laboratory findings. Management focuses on supportive care and treatment of complications. In severe hepatic VOD after transplantation, defibrotide is an approved therapy. Preventive strategies emphasize risk assessment, careful dosing of cytotoxic regimens, and close monitoring for early signs of venous outflow obstruction.