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Portal vein thrombosis (PVT) is a condition characterized by partial or complete obstruction of the portal vein lumen by thrombus, which may be acute or chronic.

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It results in impaired portal venous flow and portal hypertension, with or without hepatic ischemia depending on collateral circulation and extent of occlusion.

Classification

• Acute PVT: sudden occlusion, abdominal pain, fever, ascites, risk of intestinal ischemia (if mesenteric extension).
• Chronic PVT: long-standing; cavernomatous transformation (multiple periportal collaterals replacing thrombosed vein); presents with portal hypertension (varices, splenomegaly).
• Bland vs Tumor thrombus:
  • Bland: thrombotic clot.
  • Tumor: direct invasion by HCC or metastasis (shows arterial enhancement on imaging).

![Classification of portal vein thrombosis. (A). It is crucial to characterize the extension of the portal vein thrombosis and its relationship with the main portal vein (MPV). The involvement of the superior mesenteric vein (SMV) and splenic vein (SV) should be properly characterized due to its implication in prognosis and treatment. (B). Cavernous transformation of the portal vein. Atrophy of the MPV (marked in red) secondary to chronic PVT causes hypertrophy in the vasa vasorum of the portal vein with the apparition of porto-portal shunts.

Odriozola A, Puente Á, Cuadrado A, Rivas C, Anton Á, González FJ, Pellón R, Fábrega E, Crespo J, Fortea JI. Portal Vein Thrombosis in the Setting of Cirrhosis: A Comprehensive Review. Journal of Clinical Medicine. 2022; 11(21):6435. https://doi.org/10.3390/jcm11216435](attachment:2898b10f-5966-4bf1-9148-62e5276f6c9a:jcm-11-06435-g002.png)

Classification of portal vein thrombosis. (A). It is crucial to characterize the extension of the portal vein thrombosis and its relationship with the main portal vein (MPV). The involvement of the superior mesenteric vein (SMV) and splenic vein (SV) should be properly characterized due to its implication in prognosis and treatment. (B). Cavernous transformation of the portal vein. Atrophy of the MPV (marked in red) secondary to chronic PVT causes hypertrophy in the vasa vasorum of the portal vein with the apparition of porto-portal shunts.

Odriozola A, Puente Á, Cuadrado A, Rivas C, Anton Á, González FJ, Pellón R, Fábrega E, Crespo J, Fortea JI. Portal Vein Thrombosis in the Setting of Cirrhosis: A Comprehensive Review. Journal of Clinical Medicine. 2022; 11(21):6435. https://doi.org/10.3390/jcm11216435

Etiopathogenesis

Risk Factors

| Local factors (≈30–40%) | • Cirrhosis (most common cause). • Hepatocellular carcinoma (HCC) or other abdominal malignancies (pancreas, stomach). • Abdominal infections/inflammation: appendicitis, diverticulitis, pancreatitis, cholangitis. • Post-surgical or post-procedural (splenectomy, TIPS, liver transplantation). | | --- | --- | | Systemic / Prothrombotic states (≈30%) | • Myeloproliferative disorders (JAK2 mutation, polycythemia vera). • Antiphospholipid antibody syndrome. • Protein C, S, antithrombin III deficiency. • Factor V Leiden, Prothrombin G20210A mutation. • Oral contraceptives, pregnancy, postpartum state. | | Idiopathic (≈30%) | |

Clinical Features

Acute PVT

• Sudden abdominal pain, nausea, fever.
• Ascites.
• Possible intestinal ischemia (if mesenteric involvement).

Chronic PVT

• Features of portal hypertension: splenomegaly, variceal bleeding, hypersplenism.