From the Guidelines
Portal vein thrombosis (PVT) is primarily caused by cirrhosis of the liver, which accounts for approximately 25-30% of cases, due to altered blood flow and coagulation abnormalities, as well as other factors such as portal hypertension, slow portal flow, metabolic syndrome, and hepatocellular carcinoma, as supported by the most recent study 1. The causes of PVT can be multifactorial, including:
- Cirrhosis of the liver, which is the most common cause, accounting for approximately 25-30% of cases, due to altered blood flow and coagulation abnormalities 1
- Portal hypertension, which can lead to enlargement of the portal vein and formation of porto-systemic collateral vessels, increasing the risk of PVT 1
- Metabolic syndrome, which has been reported as a risk factor for PVT in patients with cirrhosis 1
- Hepatocellular carcinoma, which can cause PVT through direct invasion or compression of the portal vein 1
- Other factors, such as slow portal flow, which can contribute to the development of PVT 1 It is essential to understand these causes to properly manage and prevent complications such as portal hypertension and intestinal ischemia. The pathogenesis of PVT is thought to differ from more common venous thrombotic diseases, with the portal venous system being unique in that it does not drain blood to the heart, but to hepatic sinusoids in the liver, and the portal vein does not have venous valves, which are important in the development of deep vein thrombosis (DVT) 1. Recent studies have shown that anticoagulant therapy is central to the management of non-malignant PVT in patients with cirrhosis, and that it is safe and effective in preventing the development of PVT, with a survival benefit independent of portal vein recanalization 1. However, the value of thromboprophylactic therapy aimed at primary prevention of PVT is unclear, and further studies are needed to determine the optimal management of PVT in patients with cirrhosis. In terms of risk factors, patients with cirrhosis have PVTs identified on Doppler ultrasound should undergo anticoagulation, and measurable pro-coagulant changes in hemostasis in cirrhosis have not been predictive of PVT development 1. The American Association for the Study of Liver Diseases proposes that PVT be characterized by chronicity, extent, degree of lumen obstruction, and responsiveness to therapy, and recent PVT is pragmatically defined as occurring within the last 6 months, based on data suggesting that PVTs that are not recanalized within 6 months are unlikely to recanalize with anticoagulation 1. Overall, the management of PVT in patients with cirrhosis requires a comprehensive approach, taking into account the underlying causes and risk factors, as well as the latest evidence on anticoagulant therapy and thromboprophylaxis.
From the Research
Causes of Portal Vein Thrombosis
- Liver cirrhosis is a common cause of portal vein thrombosis (PVT), as stated in studies 2, 3, 4, 5, 6
- Hepatobiliary malignancy is also a cause of PVT, as mentioned in study 3
- Abdominal infectious or inflammatory diseases can lead to PVT, as reported in study 3
- Myeloproliferative disorders are another cause of PVT, as stated in study 3
- Acquired and inherited clotting abnormalities may play a role in the development of PVT in cirrhosis, as mentioned in study 6
Risk Factors
- The severity of cirrhosis is a risk factor for the occurrence and progression of PVT, as stated in studies 4, 5
- The presence of hepatocellular carcinoma is a risk factor for PVT, as mentioned in study 3
- The formation of collateral veins can allow many patients to remain asymptomatic, but can also prevent the onset of clinical complications, as reported in study 6