In brief
What the examination assesses
Examination of the IVC gives indirect information on right-sided filling pressures. VExUS adds Doppler of the hepatic veins, portal vein and intrarenal veins to look for transmission of venous pressure to the organs.
Acquisition
Duplex ultrasound of the inferior vena cava
- Use a convex (about 2.5–5 MHz) or cardiac probe and image the IVC in a longitudinal subcostal view.
- Display the terminal segment of the IVC and measure its diameter about 1–2 cm from the right atrium, just proximal to the entry of the main hepatic vein. In M-mode, place the cursor perpendicular to the walls, about 1.5 cm from the atrial junction.
- Record the maximum internal diameter at end-expiration during spontaneous breathing (Dmax). During a rapid, deep sniff with the mouth closed, record the minimum diameter (Dmin).
- For the VExUS protocol, also acquire pulsed-wave Doppler traces of the hepatic, portal and intrarenal veins, with scale, filter, gain and sample volume set to distinguish the flow components.
Report both diameters, the percentage and the respiratory manoeuvre used: a percentage on its own loses the dimensional context of the cava.
Indicative interpretation
Collapsibility and RAP/CVP estimation
According to the 2025 ASE recommendations, in spontaneous breathing the maximum diameter is combined with the inspiratory change. The algorithm assigns indicative discrete values of right atrial pressure (RAP), also used as a proxy for central venous pressure (CVP).
| Maximum IVC diameter | Inspiratory collapse | Indicative RAP | Cautious reading |
|---|---|---|---|
| ≤ 2.1 cm | > 50%* | 3 mmHg (range 0–5) | Normal or low RAP; on its own this does not diagnose hypovolaemia |
| ≤ 2.1 cm | ≤ 50% | 8 mmHg (range 5–10) | Intermediate value; combine with secondary indices |
| > 2.1 cm | ≥ 50% | 8 mmHg (range 5–10) | Discordant result; combine with other findings |
| > 2.1 cm | < 50% | 15 mmHg (range 10–20) | Right atrial pressure probably raised |
| > 2.5 cm | < 50% | Possible RAP ≥ 20 mmHg | Also requires dilated hepatic veins and reflux into the IVC or spontaneous echo contrast |
*The teaching material on which this summary is based gives collapse > 50% for the normal category; the 2025 ASE recommendations give ≥ 50% for the 3 mmHg threshold. When the measurement is exactly 50%, follow the local protocol and consider the result together with the other indices. With positive-pressure ventilation, do not automatically apply the spontaneous-breathing collapse criteria: IVC dynamics depend on ventilation and intrathoracic pressure; consider additional indices, including distensibility where appropriate.
Integrated assessment
VExUS protocol
The protocol summarised in the reference guide uses 21 mm as its operational threshold: VExUS 0 with IVC < 21 mm; with IVC ≥ 21 mm the Doppler findings in the three territories are graded. The original VExUS publication uses a threshold of 2 cm; the threshold and how a borderline value is classified should therefore be stated in the protocol adopted. The linked calculator has been aligned to 21 mm.
- Hepatic veins: PW sample about 1–2 cm from the junction with the IVC. Assess the relationship between the S and D waves and whether the S wave remains antegrade or reverses.
- Portal vein: right intercostal window on the main portal branch; assess the pulsatility of hepatopetal flow over the cardiac cycle.
- Intrarenal veins: renal scan with PW sampling of the intraparenchymal veins, usually interlobar or arcuate; determine whether flow is continuous, biphasic or diastolic only.
| Territory | Normal | Mildly abnormal | Severely abnormal |
|---|---|---|---|
| Hepatic vein | Dominant S wave or S ≥ D, antegrade flow | S wave smaller than D but still antegrade | Systolic reversal of the S wave |
| Portal vein | Pulsatility < 30% | Pulsatility 30–<50% | Pulsatility ≥ 50% |
| Intrarenal vein | Continuous venous flow | Discontinuous biphasic flow with S and D components | Monophasic pattern with D component only |
In the reference document, portal pulsatility is calculated as the change in velocity over the cardiac cycle:
| Grade | Findings with IVC ≥ 21 mm | Summary |
|---|---|---|
| VExUS 0 | IVC < 21 mm | No significant congestion according to the initial criterion of the grading adopted in the guide |
| VExUS 1 | No severe Doppler pattern; normal or mild patterns | Mild congestion |
| VExUS 2 | One severe Doppler pattern | Moderate congestion |
| VExUS 3 | At least two severe Doppler patterns | Severe congestion |
If one or more territories cannot be assessed, document it: the grading is incomplete and must not be completed by assuming the pattern is normal.
Portal PI calculator and VExUS conclusion
Enter the minimum and maximum portal velocities to calculate the pulsatility index. To generate the VExUS conclusion, add the maximum IVC diameter and the hepatic and intrarenal patterns.
Context
Limitations and interpretive caveats
- IVC dilatation may also be due to right ventricular dysfunction, tricuspid regurgitation, pulmonary hypertension, raised intra-abdominal pressure or individual characteristics.
- Atrial fibrillation and marked respiratory variation may make it advisable to average several cycles and to check trace quality.
- Cirrhosis or portal vein thrombosis may limit interpretation of the portal vein; advanced renal failure and technical difficulties may limit intrarenal Doppler.
- VExUS is an assessment of systemic venous congestion. It does not replace the history, physical examination, complete echocardiography or assessment of perfusion, and must not on its own guide fluids, diuretics or ultrafiltration.
- A small, highly collapsible IVC is not enough to diagnose hypovolaemia or to establish that the patient will tolerate fluids.
References
Key sources
- Mukherjee M, et al. Guidelines for the Echocardiographic Assessment of the Right Heart in Adults and Special Considerations in Pulmonary Hypertension. J Am Soc Echocardiogr. 2025;38(3):141–186. doi:10.1016/j.echo.2025.01.006.
- Beaubien-Souligny W, et al. Quantifying systemic congestion with Point-Of-Care ultrasound: development of the venous excess ultrasound (VExUS) grading system. Ultrasound J. 2020;12:16. doi:10.1186/s13089-020-00163-w.
- Soliman-Aboumarie H, Denault AY. How to assess systemic venous congestion with point of care ultrasound. Eur Heart J Cardiovasc Imaging. 2023;24(2):177–180. doi:10.1093/ehjci/jeac239.
- Study guide: colour Doppler of the IVC and the VExUS protocol — reference material (in Italian) provided for this summary.