Colour Doppler ultrasonography of a segmental branch of the portal vein is useful for early diagnosis and monitoring of the therapeutic course of veno-occlusive disease after allogenic haematopoietic stem cell transplantation.

We report two cases in which visualization of the segmental branch of the hepatic portal vein with the colour Doppler ultrasonography (US) technique was useful for the early diagnosis of veno-occlusive disease. The change in blood flow in the segmental branch of the portal vein occurred 5 and 6 d before the clinical criteria were fulfilled in the two cases. Reverse flow in the segmental branch began partially in the liver at first, and then spread to the whole liver several days later. All the US findings in both cases disappeared after thrombolytic therapy.