Duplex ultrasonography of the portal vein.

Although the ability of ultrasonography to provide anatomic detail and physiologic information about the arterial system is well established, its applicability for the venous system and the splanchnic circulation has only recently been recognized. We have found duplex scanning, which is non-invasive, rapid, inexpensive, and reproducible, to be highly accurate in (1) establishing or confirming the diagnosis of portal hypertension, (2) demonstrating portal and splenic vein patency and direction of flow, (3) assessing portosystemic shunt patency, and (4) providing novel anatomic and physiologic information regarding the normal and diseased splanchnic venous system. These ultrasonographic techniques also have a significant role to play in the surveillance of patients who have undergone liver transplantation or massive liver resection. To a great extent, ultrasonography may supplant the invasiveness, discomfort, and expense of contrast angiography in the evaluation of many patients with advanced liver disease.