Portal vein problems might be caused by portal hypertension - cirrhosis, malignancy or hypercoagulable - prothrombotic conditions, malignancy, oral contraceptive pill, pregnancy, trauma.
Portal vein thrombosis may present with many things including abdominal pain, nausea and fever, variceal bleeding, and encephalopathy - or be completely asymptomatic.
Treatment includes observation, anticoagulation, thrombectomy and shunts. Need to prevent thrombus extension and mesenteric ischaemia. May present as an acute ischaemic bowel.
References
https://www.gpnotebook.com/simplepage.cfm?ID=-1214644198&linkID=27047&cook=no
https://radiopaedia.org/articles/portal-vein-thrombosis?lang=gb
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4353656/
https://wikem.org/wiki/Portal_vein_thrombosis
https://journals.sagepub.com/doi/pdf/10.1177/1358863X15611224
