What is the Venous Excess Ultrasound (VEXUS) grading system?

VEXUS Grading System

The Venous Excess Ultrasound (VExUS) grading system is a point-of-care ultrasound protocol that combines inferior vena cava (IVC) diameter assessment with Doppler flow patterns from hepatic, portal, and intrarenal veins to quantify systemic venous congestion on a 0-3 scale, with Grade 3 representing severe congestion associated with acute kidney injury, diuretic resistance, and increased mortality. 1, 2

Core Components of VExUS Assessment

The VExUS system requires evaluation of four distinct ultrasound windows 1, 3:

• IVC diameter measurement: A dilated IVC (≥2 cm) serves as the foundational criterion for venous congestion 1
• Hepatic vein Doppler: Assesses pulsatility patterns reflecting right atrial pressure transmission 1, 3
• Portal vein Doppler: Evaluates flow pulsatility indicating hepatic congestion 1, 3
• Intrarenal vein Doppler: Detects flow abnormalities suggesting renal venous hypertension 1, 3

VExUS Grading Scale

The severity of venous congestion is classified into four grades 1, 2:

• Grade 0: No venous congestion—IVC <2 cm with normal Doppler patterns in all three veins 1, 2
• Grade 1: Mild congestion—IVC ≥2 cm but normal or minimal flow abnormalities in hepatic, portal, and renal veins 1, 2
• Grade 2: Moderate congestion—IVC ≥2 cm with severe flow abnormalities in one Doppler pattern 1
• Grade 3: Severe congestion—IVC ≥2 cm with severe flow abnormalities in two or more Doppler patterns 1, 2

Clinical Significance and Outcomes

VExUS Grade 3 demonstrates the strongest association with adverse clinical outcomes 1, 2:

• Acute kidney injury risk: Grade 3 increases AKI risk 11-fold (OR: 11.17,95% CI: 3.86-32.29) in acute heart failure patients 2
• Diuretic resistance: 15-fold increased risk (OR: 15.31,95% CI: 5.05-46.43) of requiring doubled furosemide doses 2
• Reduced natriuretic response: 21-fold increased odds (OR: 21.53,95% CI: 5.32-87.06) of spot urine sodium <50 mmol/L 2
• Hospital mortality: 26-fold increased risk (OR: 26.4,95% CI: 5.29-131.55) compared to lower grades 2
• Need for vasopressor/inotropic support: 12-fold increased risk (OR: 11.82,95% CI: 3.59-38.92) 2

The adjusted hazard ratio for AKI development with Grade 3 congestion remains significant (HR: 2.82,95% CI: 1.21-6.55) even after controlling for baseline AKI risk and hemodynamic support 1.

Diagnostic Performance

VExUS Grade 3 at ICU admission provides superior diagnostic utility compared to traditional central venous pressure measurements 1:

• Positive likelihood ratio: 6.37 (95% CI: 2.19-18.50) for predicting subsequent AKI 1
• Feasibility: 91% successful completion rate across all timepoints in perioperative settings 4

Clinical Applications

VExUS has demonstrated utility across multiple cardiovascular conditions 3:

• Acute decompensated heart failure: Guides diuretic therapy and predicts treatment response 2, 3
• Perioperative fluid management: Monitors volume status in noncardiac surgery patients 4, 5
• Cardiorenal syndromes: Identifies patients at risk for worsening renal function 1, 2, 3
• Cardiac surgery: Predicts postoperative AKI in the first 72 hours 1

Practical Implementation

The examination requires real-time dynamic ultrasound with Doppler capabilities 1, 3:

• Hepatic vein assessment uses pulsed-wave Doppler to characterize systolic and diastolic flow patterns 1, 3
• Portal vein evaluation detects pulsatility that should normally be absent or minimal 1, 3
• Intrarenal vein Doppler identifies discontinuous or reversed diastolic flow patterns 1, 3
• IVC diameter is measured in the subcostal view approximately 2 cm from the right atrial junction 1

Common Pitfalls

Severe congestion (Grade 3) requires both IVC dilation AND multiple abnormal Doppler patterns—isolated IVC dilation without Doppler abnormalities represents only Grade 1 congestion 1. This distinction is critical because Grade 1 does not carry the same prognostic significance as Grade 3 2.

Perioperative venous congestion is common, with 44-49% of noncardiac surgery patients developing Grade 1-2 congestion postoperatively, even when preoperative assessment showed Grade 0 4. This highlights the dynamic nature of venous congestion and the need for serial assessments rather than single timepoint evaluation 4.