Portal vein thrombosis (PVT) is partial or complete thrombotic occlusion of the portal vein or its branches. Cirrhosis (25-40% of PVT cases), hepatocellular carcinoma (tumor thrombus), myeloproliferative disorders, hypercoagulable states (protein C/S deficiency, antiphospholipid syndrome, JAK2 mutation), pancreatitis, abdominal surgery, and intra-abdominal infection are major etiological factors. Acute PVT may present with abdominal pain, ascites, and bowel ischemia. Chronic PVT develops cavernous transformation (portal cavernoma — multiple tortuous collateral veins at portal hilum), portal hypertension, splenomegaly, and esophageal varices. CT angiography is the primary diagnostic method; filling defect in portal vein lumen, surrounding collateral venous enlargement, and mesenteric congestion are evaluated. Tumor thrombus vs bland thrombus distinction determines treatment plan.
Age Range
30-75
Peak Age
50
Gender
Equal
Prevalence
Uncommon
Virchow's triad plays a role in PVT development: (1) Portal flow stasis — portal hypertension and hepatofugal flow in cirrhosis, venous congestion in heart failure. (2) Vessel wall injury — portal vein endothelial damage from pancreatitis, surgery, or infection. (3) Hypercoagulability — myeloproliferative disorders (JAK2 V617F mutation positive in 17-35% of PVT), protein C/S deficiency, antiphospholipid syndrome, paroxysmal nocturnal hemoglobinuria. In hepatocellular carcinoma, tumor cells directly invade the portal vein lumen → tumor thrombus forms; this thrombus shows enhancement unlike bland thrombus (tumor neovascularity). In acute PVT, thrombus occludes the portal vein lumen → portal pressure increases → bowel and splenic congestion → ascites, mesenteric edema, bowel ischemia. In chronic PVT, the body develops cavernous transformation to bypass the thrombus: multiple small tortuous venous channels (portal cavernoma) form at the portal hilum → partial portal flow restoration but portal hypertension persists. The filling defect on CT represents the thrombus appearing as a low-density area within the contrast-filled lumen.
Portal cavernoma, the pathognomonic finding of chronic portal vein thrombosis, is the formation of multiple tortuous venous channels replacing the normal portal vein at the portal hilum. These channels are compensatory collateral veins attempting to provide hepatopetal flow bypassing the occluded portal vein. Appears as serpiginous enhancing channels on portal venous phase CT. This finding, which is the definitive diagnostic criterion of chronic PVT, is also critical in distinguishing from acute PVT.
Low-density filling defect in the main portal vein trunk and/or branches on portal venous phase CT — cardinal finding of acute PVT. If thrombus is partial, 'tram track' sign may be seen (contrast-filled lumen surrounding the thrombus). Complete occlusion shows non-opacification of lumen. Portal vein diameter may increase in acute thrombosis (>13 mm). Periportal edema (fatty stranding) indicates acute inflammation. Thrombus hypodensity is usually 20-40 HU (soft tissue density). Density slightly increases in subacute thrombus (organized thrombus).
Report Sentence
Intraluminal hypodense filling defect in the main portal vein trunk/right-left branches on portal venous phase, consistent with acute portal vein thrombosis.
Enhancement within the thrombus in the portal vein lumen on arterial phase — key finding for distinguishing tumor thrombus from bland thrombus. HCC-related tumor thrombus shows prominent enhancement on arterial phase due to tumor neovascularity. Bland thrombus shows no enhancement. Thrombus density increase >20 HU on arterial phase (compared to non-contrast CT) supports tumor thrombus. Portal vein diameter >23 mm suggests tumor thrombus. Neovascularity — new vessel formation within thrombus may appear as thin linear enhancement on arterial phase. Tumor thrombus indicates portal vein invasion of HCC (BCLC stage C).
Report Sentence
The thrombus in the portal vein lumen shows enhancement on arterial phase, consistent with tumor thrombus related to hepatocellular carcinoma (BCLC stage C).
Formation of multiple tortuous venous channels at the portal hilum replacing the portal vein in chronic PVT — portal cavernoma/cavernous transformation. CT shows organized thrombus or calcification in portal vein lumen with surrounding serpiginous (tortuous) enhancing venous channels. These collateral channels attempt to provide hepatopetal (toward liver) flow. Portosystemic collaterals develop along with portal cavernoma (esophageal/gastric varices, umbilical vein recanalization, splenorenal shunt, retroperitoneal collaterals). Splenomegaly accompanies. Portal biliopathy — compression of bile ducts by cavernoma causing dilatation — is a late complication.
Report Sentence
Multiple tortuous venous channels (portal cavernoma/cavernous transformation) replacing the normal portal vein at the portal hilum, consistent with chronic portal vein thrombosis.
Echogenic material (thrombus) in the portal vein lumen on B-mode ultrasound. Acute thrombus may be hypoechoic or isoechoic — sometimes not visible on B-mode. Absence or partial flow in the portal vein on Doppler — no flow signal in complete occlusion, residual flow around thrombus in partial thrombosis. Echogenic calcified thrombus and cavernous transformation in chronic thrombus (multiple small venous channels at portal hilum). Color Doppler may show hepatofugal flow (away from liver) — sign of portal hypertension. Splenomegaly and ascites may accompany.
Report Sentence
Echogenic thrombus in the portal vein lumen and absent/decreased flow on Doppler on ultrasound, consistent with portal vein thrombosis.
Extension of portal vein thrombosis to superior mesenteric vein (SMV) and/or inferior mesenteric vein (IMV) branches. CT shows filling defect in SMV/IMV, thrombus in mesenteric venous arcades, and bowel wall thickening + mesenteric edema combination. Bowel wall enhancement may decrease (ischemia) or show hyperemic enhancement (congestion). Pneumatosis intestinalis (gas in bowel wall) and portomesenteric venous gas — late and severe ischemia/infarction findings. Mesenteric vein involvement may create acute abdomen presentation and requires surgical evaluation.
Report Sentence
Portal vein thrombosis extends to the superior mesenteric vein with accompanying bowel wall thickening and mesenteric edema suggesting mesenteric ischemia; urgent surgical evaluation is recommended.
MRI signal characteristics of portal vein thrombus enable assessment of thrombus age and tumor thrombus differentiation. Acute thrombus: isointense-slightly hyperintense on T1 (deoxyhemoglobin/methemoglobin), slightly hyperintense on T2. Chronic thrombus: hypointense on T1 and T2 (hemosiderin, fibrosis). Tumor thrombus: thrombus showing arterial enhancement and diffusion restriction on DWI → pathognomonic for tumor thrombus. Phase-contrast or time-of-flight techniques can evaluate portal vein flow on MRI without contrast. Gadolinium-enhanced MRI shows prominent arterial enhancement in tumor thrombus.
Report Sentence
Arterial enhancement and diffusion restriction on DWI in the portal vein thrombus on MRI, consistent with tumor thrombus; portal vein invasion by HCC should be considered.
Criteria
Symptom onset <60 days. Hypodense filling defect in portal vein lumen, portal vein diameter enlarged (>13 mm), periportal edema. No cavernous transformation.
Distinct Features
Anticoagulation therapy effective (85% recanalization). Bowel ischemia risk with mesenteric vein extension. Thrombolytic therapy may be considered in selected cases. Portal vein diameter wider than normal.
Criteria
Cavernous transformation and/or portosystemic collateral development. Organized/calcified thrombus. Portal vein diameter decreased or normal. Portal hypertension signs (splenomegaly, varices, ascites).
Distinct Features
Anticoagulation does not achieve recanalization but prevents progression. Variceal bleeding risk — endoscopic band ligation/sclerotherapy. Portal biliopathy may develop. TIPS (transjugular intrahepatic portosystemic shunt) may be considered.
Criteria
Portal vein tumor invasion due to HCC or other hepatic/perihepatic malignancies. Enhancement within thrombus on arterial phase (tumor neovascularity). Portal vein diameter enlarged (>23 mm). Diffusion restriction in thrombus on DWI.
Distinct Features
Elevates to BCLC stage C in HCC → curative treatment (resection/transplantation) generally not suitable. Sorafenib/lenvatinib systemic therapy indication. Anticoagulation contraindicated. Portal vein diameter >23 mm is 95% specific for tumor thrombus.
Distinguishing Feature
HCC-related tumor thrombus shows arterial phase enhancement and significantly enlarges portal vein diameter (>23 mm); bland thrombus shows no enhancement and portal vein diameter is less enlarged. Tumor thrombus usually shows continuity with HCC mass. Diffusion restriction is present in tumor thrombus on DWI.
Distinguishing Feature
IVC thrombosis involves hepatic veins and IVC; PVT involves the portal venous system. Both show filling defects but anatomical location differs. IVC thrombosis is more commonly associated with lower extremity DVT; PVT is more commonly associated with cirrhosis and intra-abdominal pathology. In Budd-Chiari syndrome, hepatic vein and IVC thrombus may coexist — creating a different clinical picture from PVT.
Distinguishing Feature
SMA thrombosis/embolism involves the arterial system and causes mesenteric ischemia through a different mechanism (arterial inflow loss); PVT involves the venous system (venous outflow obstruction). In SMA occlusion, filling defect or abrupt cutoff in SMA on arterial phase; in PVT, filling defect on portal venous phase. Arterial and venous causes of mesenteric ischemia differ in treatment approach.
Distinguishing Feature
Intrahepatic cholangiocarcinoma (ICC) may encapsulate or invade portal vein branches but tumor thrombus is rare compared to HCC. ICC is usually hypovascular and does not show arterial enhancement; HCC is hypervascular and tumor thrombus shows arterial enhancement. Bile duct dilation and capsular retraction are more common in ICC; cirrhosis and AFP elevation more commonly accompany HCC.
Urgency
urgentManagement
medicalBiopsy
Not NeededFollow-up
3-monthPVT treatment is determined by etiology, acute/chronic distinction, and tumor thrombus presence. Acute bland PVT: Anticoagulation (low-molecular-weight heparin → warfarin or DOAC) for 3-6 months; 85% recanalization rate within first 6 months. Mesenteric vein involvement + bowel ischemia: urgent surgical evaluation + anticoagulation + thrombectomy/thrombolytic therapy may be considered. Chronic PVT: Management of portal hypertension complications (endoscopic treatment for variceal bleeding, diuretics for ascites); anticoagulation prevents progression but does not achieve recanalization. Tumor thrombus: Anticoagulation contraindicated; BCLC stage C in HCC → systemic therapy (sorafenib/lenvatinib); palliative radiotherapy or TACE may be considered. Etiological workup mandatory: myeloproliferative disease (JAK2 V617F), hypercoagulability screening, cirrhosis evaluation, HCC screening.
Acute PVT is treated with anticoagulation; acute bowel ischemia requires emergency surgery. PVT in cirrhosis affects liver transplant planning. Tumor thrombus presence in HCC makes Barcelona staging (BCLC) C, indicating chemotherapy/sorafenib. In chronic PVT, portal hypertension and variceal bleeding management is important.