Duplex sonography and colour Doppler in the diagnosis and follow-up of portal vein thrombosis

Clinical findings in acute portal vein thrombosis are often limited and non-specific. Many portal vein thromboses probably remain undiagnosed during the acute stage, and some of these may be discovered later because of complications such as variceal bleeding. Ultrasound with pulsed Doppler and colour Doppler is useful in the diagnosis of the thrombus, and for evaluation of its extension, hemodynamic significance and complications. We present a case of acute portal vein thrombosis associated with protein S deficiency, and review the findings of ultrasound and Doppler in the light of those previously reported. We describe the lack of Doppler signal in the splenic vein and inability to visualize the portal vein and its intra-hepatic branches as one normally can. Further observations include a thrombosed portal vein branch within the liver, prominent branches of the hepatic artery, splenomegaly, partial recanalization and development of collaterals. In the hepatic veins, we found pathologic blood flow with reduced heart-synchronous variations of velocity, as often found in portal hypertension due to cirrhosis. This is not previously reported in portal vein thrombosis, and may be a sign of a portal vein thrombosis with a large degree of obstruction to blood flow and development of portal hypertension. This phenomenon can be explained using hemodynamics.