Venous Excess Ultrasound (VExUS): Definition and Interpretation
VExUS is a point-of-care ultrasound protocol that rapidly assesses systemic venous congestion by integrating analysis of the inferior vena cava (IVC) and Doppler waveforms from multiple venous beds—specifically the hepatic vein, portal vein, and intrarenal veins—to grade the severity of venous congestion and guide therapeutic interventions. 1, 2
What VExUS Measures
VExUS differs fundamentally from traditional venous ultrasound for DVT evaluation. While standard venous ultrasound focuses on detecting thrombosis through compression techniques 3, VExUS evaluates hemodynamic congestion resulting from elevated right atrial pressure and functional right ventricular failure 4.
The examination integrates:
- IVC diameter assessment to evaluate central venous pressure 2
- Hepatic vein Doppler waveforms to detect flow reversal patterns 2
- Portal vein Doppler patterns to identify pulsatility from venous congestion 2
- Intrarenal venous Doppler to assess kidney congestion 2
How to Perform VExUS
Technical Approach
- Use a low-frequency curvilinear probe (typically 2-5 MHz) for adequate tissue penetration 2
- Position the patient supine with the probe in the subxiphoid or right subcostal region 2
- Optimize Doppler settings with appropriate scale, gain, and angle correction (<60 degrees) 2
- ECG tracing should be used concurrently during image acquisition, as this significantly improves inter-rater reliability and reproducibility 5
Examination Sequence
- IVC measurement: Assess diameter and collapsibility in the subcostal view 2
- Hepatic vein Doppler: Evaluate for normal triphasic flow versus abnormal patterns (biphasic, monophasic, or flow reversal) 2
- Portal vein Doppler: Assess for abnormal pulsatility (>30-50% variation) 2
- Intrarenal venous Doppler: Examine for discontinuous versus continuous flow patterns 2
VExUS Grading System
The VExUS score stratifies congestion severity from 0-3 based on IVC diameter and the number of abnormal venous Doppler patterns: 2
- Grade 0: IVC <2 cm with normal Doppler patterns in all three venous beds
- Grade 1: IVC ≥2 cm with normal Doppler patterns in all three venous beds
- Grade 2: IVC ≥2 cm with severe abnormalities in one venous bed
- Grade 3: IVC ≥2 cm with severe abnormalities in two or more venous beds
Severe Doppler Abnormalities Defined
- Hepatic vein: Monophasic flow or flow reversal 2
- Portal vein: Pulsatility >50% 2
- Intrarenal vein: Discontinuous (monophasic) flow 2
Clinical Interpretation and Applications
VExUS provides real-time assessment of venous congestion that cannot be reliably detected by physical examination or standard laboratory tests alone. 4, 2
Key Clinical Uses
- Fluid management decisions in critically ill patients to avoid worsening congestion 1
- Assessment of organ perfusion in shock states where venous congestion contributes to organ dysfunction 1
- Guiding diuresis in heart failure and volume overload states 4
- Evaluating hemodynamic status in patients with acute kidney injury where venous congestion may be contributing 4
Reliability Considerations
- VExUS demonstrates substantial inter-rater reliability (Kappa 0.71, ICC 0.83) when interpreted by clinicians from diverse specialties 5
- ECG-augmented VExUS shows greater agreement among interpreters compared to non-ECG studies 5
- The technique is reproducible (Kappa 0.63, ICC 0.8) across different users 5
Critical Pitfalls to Avoid
- Do not confuse VExUS with DVT evaluation: VExUS assesses hemodynamic congestion, not thrombosis 3, 1
- Inadequate Doppler angle correction (>60 degrees) leads to inaccurate velocity measurements 2
- Respiratory variation can significantly affect waveforms; obtain measurements during quiet breathing 2
- Cardiac arrhythmias may complicate waveform interpretation; ECG correlation is essential 5
- Operator dependency requires adequate training in Doppler techniques for accurate interpretation 2