Inferior vena cava (IVC) thrombosis is thrombus formation within the IVC lumen. Two main types exist: bland (non-tumoral) thrombosis and tumor thrombus. Bland thrombosis most commonly develops from lower extremity deep vein thrombosis (DVT) propagation, hypercoagulability syndromes (antiphospholipid syndrome, Factor V Leiden, malignancy), IVC compression (retroperitoneal mass, gravid uterus), or IVC filter presence. Tumor thrombus is most commonly associated with renal cell carcinoma (4-10% IVC invasion), hepatocellular carcinoma, and adrenocortical carcinoma — tumor cells extend into the IVC via the renal vein or hepatic veins. Bland vs tumor thrombus distinction is critical for treatment planning: bland thrombosis is treated with anticoagulation, while tumor thrombus requires surgical thrombectomy and/or neoadjuvant therapy. CT venography (CTV) is the gold standard for diagnosis; thrombus enhancement pattern (bland: non-enhancing, tumor: enhancing), DWI restriction, and IVC diameter are the main distinguishing criteria.
Age Range
30-75
Peak Age
55
Gender
Equal
Prevalence
Uncommon
IVC thrombosis develops from activation of one or more components of Virchow's triad: stasis (DVT propagation, IVC compression, or immobilization), endothelial injury (IVC filter, catheter, or surgical trauma), and hypercoagulability (malignancy, thrombophilia, or hormonal therapy). In bland thrombosis, fibrin network, platelets, and red blood cells form a homogeneous thrombus — no vascularization exists, therefore it shows no enhancement. On CT, bland thrombus separates from surrounding enhanced blood (150-250 HU) by its low density (30-60 HU). In tumor thrombus, neoplastic cells enter the venous system through direct invasion — in renal cell carcinoma, tumor cells extend from the intimal surface of the renal vein into the IVC lumen. Tumor thrombus contains neovascularization (tumoral angiogenesis) → shows enhancement (arterial phase enhancement distinguishes from bland thrombus). On DWI, tumor thrombus shows diffusion restriction because high cellularity restricts intracellular water movement (hyperintense on high b-value, low ADC) → bland thrombus shows no or minimal diffusion restriction. IVC thrombosis leads to collateral development in the azygos-hemiazygos and lumbar venous systems — these collaterals become prominent in chronic thrombosis.
Arterial phase enhancement and DWI diffusion restriction of the IVC luminal thrombus are the most reliable distinguishing criteria for tumor thrombus. The combination of these two findings strongly supports tumor thrombus diagnosis and mandates investigation for primary malignancy.
Low-density filling defect within the IVC lumen on portal venous phase contrast CT. Acute bland thrombus is homogeneously hypodense (30-60 HU), creating marked contrast against surrounding enhanced blood (150-250 HU). Proximal and distal extent of the thrombus, renal vein and hepatic vein involvement should be carefully assessed. Calcification and IVC wall thickening may accompany chronic thrombosis.
Report Sentence
Low-density filling defect measuring __ mm in length within the IVC lumen, consistent with IVC thrombosis.
Enhancement of the thrombus within the IVC lumen on arterial phase CTA is pathognomonic for tumor thrombus. Tumor thrombus shows heterogeneous enhancement on arterial phase because it contains neovascularization — >20 HU increase from precontrast density is considered significant enhancement. The enhancement pattern of tumor thrombus resembles the primary tumor (e.g., RCC tumor thrombus shows hypervascular arterial enhancement). Bland thrombus shows no enhancement.
Report Sentence
Enhancement of thrombus within the IVC lumen on arterial phase, consistent with tumor thrombus; investigation for primary malignancy is recommended.
On MRI DWI, tumor thrombus shows markedly hyperintense signal on high b-value (b=800-1000) and hypointense signal on ADC map — diffusion restriction. Bland thrombus shows no restriction or minimal isointensity on DWI. DWI restriction combined with enhancement is the most reliable criterion for distinguishing tumor from bland thrombus. ADC value of tumor thrombus is generally <1.0 × 10⁻³ mm²/s while bland thrombus shows >1.2 × 10⁻³ mm²/s.
Report Sentence
Thrombus within the IVC lumen shows diffusion restriction on DWI, consistent with tumor thrombus.
In chronic IVC thrombosis, compensatory dilatation of azygos and hemiazygos veins, prominence of the lumbar venous plexus, and paravertebral-epidural venous collateral development is seen. Azygos vein diameter >10 mm and hemiazygos vein diameter >7 mm are considered abnormal. Anterior abdominal wall superficial veins (caput medusae-like) and gonadal vein dilatation may also accompany. Collateral extent reflects the level and chronicity of obstruction.
Report Sentence
Compensatory dilatation of azygos and hemiazygos veins with lumbar venous collateral development, consistent with chronic IVC obstruction.
On US, echogenic material (thrombus) within the IVC lumen. Acute thrombus is low echogenicity (hypoechoic) and partially or completely fills the lumen. Chronic thrombus appears hyperechoic and heterogeneous as it becomes organized. On Doppler, no flow signal in lumen occlusion; residual flow detected in partial thrombosis. IVC diameter change with Valsalva maneuver decreases or disappears in chronic thrombosis (loss of compliance).
Report Sentence
Echogenic thrombus material in the IVC lumen with __ (no flow / residual flow) on Doppler; consistent with IVC thrombosis.
IVC thrombus can be aged on MRI based on T1 and T2 signal characteristics, and type distinction can be supported. Acute bland thrombus is isointense on T1, hypointense on T2 (deoxyhemoglobin). Subacute bland thrombus is hyperintense on T1 (methemoglobin). Tumor thrombus is heterogeneously hyperintense on T2 and shows enhancement on contrast-enhanced sequences. Non-contrast TOF MRA may be useful for thrombus and patent lumen differentiation.
Report Sentence
Thrombus in the IVC lumen shows heterogeneous T2 hyperintensity and enhancement, should be evaluated for tumor thrombus.
Criteria
No enhancement, no or minimal DWI restriction, IVC diameter generally normal. In the setting of DVT propagation, hypercoagulability, filter, or compression.
Distinct Features
Treated with anticoagulation. Thrombus is homogeneously hypodense. Chronic form may show IVC wall thickening and calcification.
Criteria
Arterial phase enhancement, DWI restriction, IVC diameter expansion (>28 mm). Continuity with primary tumor (via renal vein or hepatic vein).
Distinct Features
Most commonly RCC (4-10%), HCC, and adrenocortical carcinoma. Surgical thrombectomy +/- neoadjuvant therapy. IVC involvement level (infrahepatic, retrohepatic, suprahepatic, intra-atrial) determines surgical approach.
Criteria
Organized thrombus or complete occlusion in IVC lumen, extensive venous collateral development, IVC wall thickening and/or calcification.
Distinct Features
Bilateral lower extremity edema, venous ulcers, varicose veins. IVC reconstruction (stent or bypass) may be needed. Overlap with Budd-Chiari syndrome possible (in hepatic vein thrombosis).
Distinguishing Feature
In IVC filter complications, metallic filter structure is visible in the lumen; thrombus accumulation around the filter and filter migration/penetration are distinguishing.
Distinguishing Feature
Portal vein thrombosis is in the portal venous system, no IVC involvement. Portal hypertension findings (splenomegaly, varices) accompany. IVC thrombosis is in the systemic venous system.
Distinguishing Feature
In RCC tumor thrombus, continuity of enhancing thrombus from renal mass through renal vein into IVC is pathognomonic. In isolated bland thrombosis, no primary renal mass.
Distinguishing Feature
In HCC tumor thrombus, hepatic liver mass and enhancing thrombus continuity from hepatic vein into IVC is seen. Cirrhotic liver background supports the diagnosis.
Urgency
urgentManagement
medicalBiopsy
Not NeededFollow-up
3-monthIVC thrombosis management varies by type distinction. Bland thrombosis: anticoagulation (heparin → warfarin/DOAC), IVC filter (if anticoagulation contraindicated), compression therapy. Tumor thrombus: primary tumor treatment + surgical thrombectomy — IVC involvement level (infrahepatic vs suprahepatic vs intra-atrial) determines surgical approach; suprahepatic/atrial extension may require cardiac bypass. Neoadjuvant TKI (sunitinib/pazopanib in RCC) may shrink the thrombus. Follow-up: CTV every 3-6 months for thrombus regression, collateral development, and complication (PE, Budd-Chiari) assessment.
IVC thrombosis treatment depends on etiology: anticoagulation for bland thrombosis, surgery (thrombectomy + tumor resection) for tumor thrombus. Tumor thrombus level (infrahepatic/hepatic/suprahepatic/atrial) affects surgical planning. Pulmonary embolism risk exists. IVC thrombus extension in RCC changes staging.