Non Cirrhotic Portal Vein Thrombosis (PVT)

Description

Portal vein thrombosis (PVT) is a partial or complete obstruction of the portal vein (the blood vessel that carries blood from the intestines and spleen to the liver) due to a blood clot (thrombus). The location of the thrombus varies and can be present in the main portal vein trunk and/or in the intrahepatic branches and can possibly involve splenic vein or the mesenteric veins. PVT can occur in cirrhotic and non-cirrhotic patients with different causes and pathogenesis. 

On this page we refer to non malignant non-cirrhotic and non malignant PVT.

What are the symptoms?

PVT can present acutely (usually with symptoms) or can be identifed at a chronic stage with complications due to increased increased pressure in the portal vein (Portal Hypertension). Acute and chronic PVT are managed differently.

Recent PVT: The severity of recent PVT presentation depends mainly on the extent of thrombosis. Extensive and complete thrombosis can cause intestinal ischemia, and if not urgently treated, intestinal infarction, a very severe condition. Symptoms are: abdominal pain, bleeding from the gastrointestinal tract, occasionally fever, diarrhea with or without blood in stool.

Chronic PVT: Persistence of thrombosis more than 6 months after the acute event. As a  result of chronic portal vein obstruction cavernomatous transformation can occur. Cavernoma is a network of porto-portal collaterals. About half of recent PVT evolve to chronic PVT/cavernoma despite treatment. Chronic PVT can be asymptomatic or symptomatic (complications related to portal hypertension: esophageal and gastric varices with gastrointestinal bleeding; ascites and hepatic encephalopathy. Rarely febrile episodes and cholangitic complications for portal biliopathy (extrinsic compression of the bile ducts by the cavernoma) can occur. 

Diagnosis

The diagnosis of PVT is reached through non-invasive imaging tests 

• Ultrasound with Doppler study: a procedure that transmits high-frequency sound waves through body tissues. The echoes are recorded and transformed into video or photographs of the internal structures of the body. Doppler study allows to see the vessels that goes to and move away from the liver. If a clot exists, usually it is seen with this technique.
• Computed Tomography (CT) scan and Magnetic Resonance Imaging (MRI):  second-level imaging to define clot presence and extension. CT uses X-rays and MRI uses uses a large magnet, radio waves, and a computer to produce very clear pictures of the body.  

What are the causes?

Etiological factors for PVT can be divided into local and systemic factors. 

The most frequent local risk factors in non-cirrhotic PVT are intra-abdominal surgery, infections, or abdominal infammation (i.e. pancreatitis). In pediatric age, previous umbilical catheterization is the most prevalent local factor. 

Underlying prothrombotic conditions  for PVT (Systemic factors) can be identified in up to 60% of patients:

• Myeloproliferative disorder (overproduction of white blood cells, red blood-cells or platelets). Myeloproliferative disorder is an acquired disease; it is not transmitted by parents at birth.
• Natural anticoagulant deficiency (protein C, protein S, antithrombin) and mutation of factor V Leiden or prothrombin gene mutation are the main congenital anomalies
• Other acquired disorders are antiphospholipid syndrome, paroxysmal nocturnal hemoglobinuria  and autoimmune disorders like Behcet’s disease
• Other risk factors are exogenous: oral contraceptives containing estrogen and pregnancy.
• Other virus infections like Covid 19 or CMV

Management

Your doctor will perform blood tests to make a diagnosis. These tests include genetic testing for genetic disorders (thrombophilia) and other tests to diagnose myeloproliferative disorders such as Jak2 V617f/exon 12  or Cal r mutations, and other tests to discard antiphospholipid syndrome ( antiphospholipid antibodies, lupus anticoagulant, anti beta2 gp1). He will also discard other more rare causes (see chapter what are the causes). All these tests need to be performed, as sometimes several causes can be identified. Diagnosis of these associated diseases may be more difficult than in the absence of PVT, and deserve exhaustive screening by expert centres. 

In the case of myeloproliferative disorder, further tests can be required, including a bone marrow biopsy or a measurement of the blood mass.

How is PVT treated?

Treatment of acute and chronic PVT is slightly different. However in both conditions the treatment is based on medical therapy with anticoagulants and radiological procedures as well as treatment of the cause.

In acute PVT anticoagulant therapy must start early. Therapy usually starts with subcutaneous injections of Low Molecular Weight Heparin (LMWH) and then continues with oral therapy (vitamin K antagonists or  direct-acting oral anticoagulants – DOAC)

Anticoagulant agents (blood thinners)

These decrease the blood’s tendency to clot and prevent future blood clots (thrombus=obstruction) which could block blood flow in the veins, and extension of a preexisting clot. Two kinds of blood thinners are available, the oral ones and those given by injection. In the case of oral treatment with vitamin K antagonists, regular blood tests are performed to measure INR. There are new oral blood thinners that do not need to be monitored.

In patients at risk of intestinal infarction despite anticoagulant therapy, radiological procedures can be considered. Interventional vascular radiology techniques (with or without pharmacological and/or mechanical thrombolysis) have been proposed for treating acute PVT to avoid intestinal ischemia and prevent portal hypertension complications. However, radiological techniques must be considered in selected cases in expert centers with multidisciplinary approach. 

In chronic PVT long-term anticoagulation treatment should be maintained in patients with  thrombophilic risk factors and history of intestinal infarction. Oral anticoagulant therapy with vitamin K antagonists or DOAC is preferable. 

Long-term treatment of PVT includes management of possible complications related to portal hypertension:

• esophageal and gastric varices at risk of bleeding: pharmacological treatment with non-selective beta blockers or endoscopic treatment with band ligation
• ascites: medical treatment (diuretics, albumin infusion) anda paracentesis

Rarely, Portal vein recanalization with endovascular radiological techniques can be considered only in selected cases, with complications, that can not be treated with pharmacological treatments. Transjugular intrahepatic portosystemic shunt (TIPS) may also be considered for recurrent ascites or variceal bleeding, associated to recanalization. TIPS is a vascular radiological procedure: a transhepatic stent is placed to connect the portal vein (or one of its branches) and the hepatic vein to reduce portal hypertension and treat its complications. The TIPS procedure reroutes blood flow in the liver and reduces pressure in all abnormal veins, including the bowel and the liver.

Do I need medical checkups? 

Yes, it is very important to have regular blood tests, imaging and outpatient clinic checkups, by hepatologists, or an experts in PVT management, in addition to the other specialists.

How can I find a specialist?

PVT may need to be managed by a doctor or a hospital network with experience or an interest in PVT. PVT is a rare disease that not every doctor has an interest in or experience with. However, some hospitals are part of the Europe-wide reference network for rare liver diseases, ERN RARE-LIVER. Therefore patients seen at hospitals within the network can benefit from the expertise of specialists who work at other hospitals within the network. For more information about the ERN RARE-LIVER, visit https://rare-liver.eu/. You can find information and patient support in the section “patients” on the ERN RARE-LIVER website (https://rare-liver.eu/).

Disclaimer

The information provided free of charge on our website has been compiled to the best of our knowledge in order to give interested readers an initial overview of possible diseases and treatment options. They are intended solely for informational purposes and in no case replace personal advice, examination or diagnosis by authorized doctors.