Management of liver sinusoidal obstruction syndrome/veno-occlusive disease in adults: a 2025 perspective from an international expert group

Sinusoidal obstruction syndrome (SOS) formerly known as Veno-occlusive disease (VOD) is a potentially fatal complication that occurs mainly after haematopoietic cell transplantation, especially allogeneic transplantation. The liver is the principal organ affected, though other organs, such as the lungs, may also be involved to a lesser extent. The condition is characterised by obstruction of the hepatic venules, leading to sinusoidal congestion, hepatic ischaemia and, in severe cases, fulminant liver failure. Recent refined diagnostic criteria, published by the European Society for Blood and Marrow Transplantation in 2023, provide a more accurate method of detecting SOS/VOD, allowing earlier intervention and better stratification of patients according to the severity of their disease. This article focuses on liver SOS/VOD and discussing key risk factors, new diagnostic methods and therapeutic strategies, with an emphasis on the early use of defibrotide, which remains the reference treatment for severe SOS/VOD.