This study involves screening for portal vein thrombosis and portal hypertension in patients with Philadelphia negative myeloproliferative neoplasms (MPNs). These include polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis.

Portal vein thrombosis and portal hypertension are serious complications that are often seen in myeloproliferative patients. These complications are usually diagnosed when patients become symptomatic, and are often already at an advanced stage. They can further progress to cause non-reversible damage to the liver, also called cirrhosis of the liver. As a result of this, patients often accumulate fluid in the abdomen which is ascites; and can develop swelling of veins in the lining of the esophagus known as varices. If untreated, varices have the risk of rupturing resulting in life-threatening bleeding. When diagnosed at an advanced stage, the treatment is usually supportive therapy and there are no treatments available at present which can reverse these conditions.

This study is looking at screening for these two conditions using Doppler ultrasound and upper gastrointestinal endoscopy.

Inclusion Criteria:

• One of the three classical Philadelphia negative myeloproliferative neoplasms (polycythemia vera (PV), essential thrombocythemia (ET) and myelofibrosis (MF)) diagnosed according to WHO or International working group-Myelofibrosis research and treatment (IWG-MRT) criteria
• Palpable spleen length greater than 5 cm below the costal margin in MF (including primary MF or post-polycythemia vera MF (PPV-MF) post-polycythemia vera ET (PPV-ET)) or palpable spleen of any size in patients with PV or ET.
• Ability to understand and willing to sign a written consent form.
• Age 18 years or older at time of consent.

Exclusion criteria:

• Known history of portal vein thrombosis
• Known history of Budd-chairi syndrome
• Known history of oesophageal varices
• Known history of cirrhosis from any cause
• Known history of active bleeding