Portal Vein Thrombosis

Portal vein thrombosis (PVT) involves partial or complete obstruction of the portal vein by thrombus, disrupting hepatic portal blood flow. Acute PVT in patients without cirrhosis typically results from local factors (abdominal infection, pancreatitis, splenectomy, intra-abdominal malignancy) or systemic hypercoagulable states (myeloproliferative neoplasms -- particularly JAK2 V617F-positive polycythemia vera, factor V Leiden, antiphospholipid syndrome). In cirrhosis, PVT develops from reduced portal flow velocity (portal hypertension), endothelial dysfunction, and local hypercoagulability. Acute PVT presents with sudden abdominal pain, nausea, and fever; extension to the superior mesenteric vein can cause intestinal ischemia and infarction (surgical emergency). Chronic PVT leads to portal hypertension with development of portosystemic collaterals and cavernous transformation of the portal vein (network of periportal collateral veins). The nurse monitors for abdominal pain (particularly if acute onset suggesting mesenteric extension), assesses for signs of portal hypertension (ascites, variceal bleeding, splenomegaly), administers anticoagulation therapy (LMWH followed by warfarin for non-cirrhotic PVT), monitors for bleeding complications of anticoagulation in cirrhotic patients, monitors liver function, and coordinates imaging surveillance for thrombus resolution.