Definition | |
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Intra-luminal: | • Web: multiple septae and/or flaps located in a cluster. |
This is an echogenic structure detected by DS or by IVUS extending from the endothelial lining of the vein wall with/without the presence of functional abnormality. Use of a diluted angiographic contrast may help identification of these abnormalities on CV. These abnormalities include web, flap, septum, membrane, hyperechoic filling defect, double parallel lumen and malformed valve. | • Flap: thin linear echogenic structure extending from the endothelial lining of a vein wall. |
• Septum: thin linear echogenic structure extending from the endothelial lining of a vein wall and attached to it at both ends. The septum may extend across a vein to attach on opposing sides or attach on the same side. | |
• Membrane: membranous structure almost occluding the entire diameter of the vein. | |
• Hyperechoic filling defect: an eccentric hyperechoic crescent with a distinct sonographic signal, reminiscent of chronic organized thrombus. | |
• Double parallel lumen: multiple small channels in the venous wall. | |
• Malformed valve: dysdynamic or fibrous valve. | |
Extra-luminal: | • Narrowing: presence of significant narrowing (defined as venous lumen reduction ≥50% respect to the proximal adjacent vein segment on CV or CSA measurement of proximal IJV ≤0.3 cm2 on DS. |
This is a restriction of the venous wall or narrowing detected on DS, CV, IVUS or MRV. These abnormalities include narrowing and annulus. | • Annulus: circumferential thickened vein wall that is restricting the vein from fully expanding with respiratory or positional changes. |
• Vein wall not reacting to a given change in transmural pressure on CV, IVUS or DS; non-compliant. | |
Abnormal IJV distensibility/pulsatility/paradox: |