TIPS evaluation is useful to ensure that the shunt is working properly and that no stenosis has occurred within the stent. Ultrasound is often used as a first-line modality.
Trending stent velocities over multiple exams adds specificity to a single evaluation. If there is a concern for a stenosis based on a combination of abnormal findings, venography can be pursued.
- normal TIPS velocity: 90-190 cm/sec
- normal portal vein velocity before entering the TIPS: ~30 cm/sec
- phasic waveform
- the portal vein branches normally reverse their flow into the shunt
- color Doppler aliasing at the site of the stenosis
- velocity of >190 cm/sec at a stenotic segment
- velocity of <90 cm/sec in nonstenotic segments
- velocity <30 cm/sec in the pre-stent portal vein (accessory sign)
- complete occlusion: lack of color Doppler flow
Always be sure to thoroughly evaluate the hepatic vein distal to the stent as well.
3D and 4D ultrasound techniques to evaluate TIPS flow volumes are being developed as a possible improvement over using velocities 3.
To be added. If you have some interventional radiology experience and would like to add to this article, click "Edit Article" above.
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