GastroenterologyTier 2Disease (DEADMAN)

Portal vein thrombosis

Description

Thrombotic occlusion of the portal vein (or its branches) - can occur in a cirrhotic liver (where portal flow is already reduced and prothrombotic factors are altered) or a non-cirrhotic liver (usually from a local precipitant or systemic hypercoagulable state)

In cirrhosis, portal vein thrombosis is relatively common and its incidence rises with disease severity; in the non-cirrhotic liver it is rarer and prompts a specific search for a local or systemic cause

Cirrhotic: reduced/turbulent portal flow (portal hypertension) plus the altered, often net-prothrombotic coagulation balance of cirrhosis
Non-cirrhotic: local factors (intra-abdominal infection/inflammation - e.g. appendicitis, pancreatitis, cholangitis - causing pylephlebitis; intra-abdominal malignancy invading/compressing the vein; prior abdominal surgery) or systemic hypercoagulable states (myeloproliferative neoplasms/JAK2 mutation, inherited thrombophilia) - a myeloproliferative neoplasm should specifically be considered in non-cirrhotic portal vein thrombosis, similar to Budd-Chiari syndrome

Can be asymptomatic (found incidentally on imaging) or present with abdominal pain, and (if extensive/acute) signs of bowel ischaemia if mesenteric venous involvement is extensive
Doppler ultrasound or contrast-enhanced CT/MRI confirms the diagnosis and defines extent (partial vs complete, and whether it extends into the mesenteric venous system)
In non-cirrhotic patients, investigate for an underlying cause (local intra-abdominal pathology, myeloproliferative neoplasm/JAK2, thrombophilia screen) given the frequency of an identifiable driver

Anticoagulation is generally indicated, particularly for acute/extensive thrombosis or in non-cirrhotic patients, to prevent extension (particularly into the mesenteric veins, risking bowel ischaemia) and promote recanalisation
In cirrhotic patients, the decision is more nuanced (bleeding risk from varices must be weighed against thrombosis progression risk) and generally involves specialist hepatology input
Treat any identified underlying cause (source control for intra-abdominal infection, cytoreductive therapy for an underlying myeloproliferative neoplasm)

Cirrhosis/portal hypertension, myeloproliferative neoplasms, intra-abdominal infection/inflammation (pylephlebitis), pancreatitis

Portal vein thrombosis can progress to involve the mesenteric venous system, risking bowel ischaemia/infarction if extensive - a key reason for prompt anticoagulation in appropriate candidates rather than simply observing an incidentally found thrombus

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