You scan the subcostal view and the IVC is big, barely moving with respiration. Does this patient need diuresis? Should you stop giving fluid? The IVC alone cannot answer either question.

A plethoric IVC is a clue to raised right atrial pressure or altered pressure transmission. First identify the cause, then decide whether the patient needs better perfusion, relief of congestion, or both. Numerical thresholds below are for adults.

What “plethoric IVC” really means (and what it doesn’t)

IVC size reflects the pressure inside the vessel relative to the surrounding pressure, together with venous compliance. Raised right atrial pressure usually distends the IVC and reduces inspiratory collapse. This estimates pressure, not circulating blood volume: acute RV pressure overload and chronic tricuspid regurgitation can produce similar images for different reasons.

Keep three questions separate: Is organ perfusion inadequate? Would increasing preload increase stroke volume (fluid responsiveness)? Can the patient tolerate added fluid without harmful pulmonary or systemic congestion? A patient can be fluid responsive and already congested. A multicenter observational study demonstrated coexisting congestion signals in 90 mechanically ventilated ICU patients receiving vasopressors; it did not establish which patients benefit from a fluid bolus.

Step 0: Make sure it’s a real plethoric IVC (scan quality pitfalls)

• Follow the IVC into the right atrium and identify hepatic venous drainage. Do not mistake the adjacent aorta for the IVC.
• Use a true long-axis view and avoid excessive probe pressure. For adult RAP estimation, the 2025 ASE guideline specifies end-expiratory diameter 0.5–3.0 cm from the RA ostium, on the abdominal side and distal to the hepatic vein. Track the same segment during respiration; translation out of plane can mimic collapse.
• Check image quality in two dimensions before trusting M-mode. Use a consistent site, position and breathing maneuver for serial measurements.

In spontaneously breathing adults, the ASE framework combines a 2.1-cm diameter cutoff with respiratory collapse to estimate RAP; discordant findings require additional indices. Its RAP estimate is not a fluid prescription. The 2-cm IVC threshold used in VExUS is a separate scoring convention, not an interchangeable diagnostic boundary for volume overload.

Step 1: Ask the ventilation question (because respiratory variation flips)

During spontaneous inspiration, falling intrathoracic pressure usually increases venous return and narrows the IVC. A forceful inspiratory effort can exaggerate collapse; shallow breathing can reduce it. With positive-pressure inspiration the IVC may instead enlarge. PEEP, tidal volume, patient effort and RV function all affect the result.

Do not apply spontaneous-breathing collapse rules to positive-pressure ventilation: IVC collapse does not reliably estimate RAP in that setting. Pulmonary hypertension and RV dysfunction also weaken simple fluid-responsiveness interpretations. A change after altering PEEP may reflect changed pressure transmission rather than removed fluid.

Step 2: Add organ venous Doppler when it can clarify congestion (VExUS logic)

Hepatic, portal and intrarenal venous Doppler can show how right-sided pressure is transmitted into organ venous drainage. They complement cardiac and lung ultrasound, examination, urine output and renal-function trends; they do not prove the cause of AKI or replace assessment of perfusion.

• Hepatic vein: systolic forward flow normally predominates. Systolic blunting or reversal can accompany congestion; severe TR and arrhythmia confound interpretation.
• Portal vein: pulsatility fraction (%) = 100 × (Vmax − Vmin) / Vmax, measured over the cardiac cycle. The original VExUS figure uses <30%, 30% to <50%, and ≥50% for normal, mildly abnormal and severely abnormal patterns.
• Intrarenal veins: normal flow is continuous. Discontinuous systolic/diastolic or diastolic-only flow is abnormal. Reserve “monophasic” for the latter.

Liver disease, intrinsic renal disease, urinary obstruction, raised intra-abdominal pressure, venous obstruction and rhythm abnormalities can confound interpretation. Severe TR and constrictive disease may cause genuine venous hypertension; an abnormal waveform still does not establish excess removable volume.

Figure: Ei Khin and colleagues, Imaging of Congestion in Cardio-renal Syndrome, Figure 3, 2025, CC BY 4.0. Its “no congestion” label denotes score 0; it does not exclude every form of congestion, including pulmonary congestion.

The original VExUS study was a post-hoc analysis of 145 cardiac-surgery patients: severe abnormalities were associated with postoperative AKI. That is prognostic association, not proof that score-guided treatment improves outcomes. A 145-patient general-ICU cohort did not find an association with AKI or 28-day mortality.

In a 140-patient randomized trial in cardiorenal syndrome type 1, VExUS-guided care improved decongestion measures but not kidney-function recovery; 90-day survival was similar. A 44-patient acute-heart-failure trial reported in a 2026 conference abstract found no significant between-group difference in NT-proBNP reduction. These results support selective use, not an automatic ED diuresis algorithm or a proven survival benefit.

Step 3: Think “plethoric IVC differential,” not “CHF by ultrasound”

• Shock or sudden deterioration: assess immediately for tamponade, acute RV failure from PE, and tension or dynamic-hyperinflation physiology. Do not delay treatment of a clear emergency to complete venous Doppler.
• Tamponade: a plethoric IVC is supportive but nonspecific. A collapsible IVC cannot exclude low-pressure tamponade. Integrate the effusion, chamber collapse, Doppler and clinical findings; obtain urgent expert assessment when suspicion remains.
• RV pressure overload: acute PE, pulmonary hypertension and cor pulmonale may elevate RAP without a simple excess-volume problem. RV strain alone does not diagnose PE.
• Raised surrounding pressure: high PEEP and auto-PEEP alter venous return; tense ascites or abdominal hypertension can distort or compress the IVC. Interpret the cause rather than labeling the image “fluid overload.”
• Chronic or local findings: athletes may have a large IVC; chronic severe TR may leave it persistently dilated. Compare previous studies. Thrombosis, masses, filters and ECMO cannulas can further alter local anatomy or flow.

ED approach when you see a plethoric IVC

Start with perfusion and respiratory status: mental state, capillary refill, blood pressure trend, urine output, oxygen requirement and the clinical meaning of lactate. Congestion can coexist with low cardiac output and hypoperfusion.

• If fluid is being considered for hypoperfusion: use a suitable dynamic test, such as passive leg raising with direct stroke-volume or cardiac-output measurement, when feasible. A positive response predicts increased flow, not necessarily clinical benefit or tolerance.
• If the clinical syndrome supports decompensated congestive heart failure: treat that syndrome and reassess. Venous Doppler may help when uncertainty remains, but treatment should not wait for a VExUS score.
• If shock, RV failure or obstruction dominates: address the cause and obtain urgent specialist support. Neither routine diuresis nor reflex fluid loading follows from a large IVC.

After an intervention, reassess perfusion, breathing, urine output, renal function and electrolytes, together with cardiac/lung and venous findings where useful. Stop or change the strategy when the intended benefit is absent or harm appears. Do not chase normalization of an isolated IVC measurement.

Take-home points

A plethoric IVC asks you to explain right-sided pressure. It does not tell you to give fluid, withhold all fluid, or diurese. Combine the mechanism, perfusion, fluid responsiveness and tolerance, then reassess the response to treatment.

Primary references

• ASE right-heart assessment guideline, 2025
• Beaubien-Souligny et al. Original VExUS derivation, 2020
• Andrei et al. General-ICU VExUS cohort, 2023
• Islas-Rodríguez et al. VExUS-guided decongestion trial, 2024
• Muñoz et al. Fluid responsiveness and venous congestion, 2024
• Sierra et al. VExUS-guided acute-heart-failure trial abstract, 2026
• Sagristà-Sauleda et al. Low-pressure tamponade, 2006