Venous excess doppler ultrasound: What radiologists should know in 2026

Abstract

Systemic venous congestion is increasingly recognized as a key contributor to organ dysfunction and adverse outcomes, particularly in the cardiorenal and critical care settings. Elevated right-sided cardiac pressures are transmitted retrogradely to the hepatic, splanchnic, and renal venous systems, leading to impaired organ perfusion, increased interstitial pressure, and complications such as acute kidney injury. Conventional clinical markers and biomarkers of congestion lack sensitivity for detecting early or subclinical venous hypertension. In contrast, ultrasound, particularly when incorporating abdominal venous Doppler assessment, enables a more granular, physiologically grounded evaluation of congestion. The venous excess ultrasound (VExUS) score integrates inferior vena cava assessment with hepatic, portal, and intrarenal venous Doppler waveforms to provide a structured framework for grading venous congestion. VExUS has been associated with renal outcomes, and morbidity and mortality in heart failure, and dynamic changes in venous Doppler patterns appear to carry prognostic significance. This review describes the physiologic basis of venous Doppler abnormalities, outlines the components and grading of the VExUS system, and highlights common technical and interpretive pitfalls that affect reliable assessment. Particular emphasis is placed on waveform morphology, electrocardiographic correlation, and optimization of Doppler acquisition. Given that abdominal Doppler studies are frequently performed for indications unrelated to heart failure, radiologists are uniquely positioned to recognize venous congestion on routine imaging. Incorporation of VExUS principles into radiologic reporting, along with standardized acquisition and multidisciplinary education, may enhance the clinical relevance of abdominal and renal vascular examinations and support earlier, physiologically informed hemodynamic intervention. This narrative review synthesizes current evidence, discusses technical and interpretive considerations, and provides practical guidance for radiologists incorporating VExUS into practice.

Key Words: Point-of-care ultrasound; Ultrasound; Venous excess ultrasound; Congestion; Radiology

Core Tip: Venous congestion is a dynamic and underrecognized potential contributor to organ dysfunction across cardiovascular and critical care settings. The venous excess ultrasound framework integrates abdominal venous Doppler findings to provide a structured, noninvasive assessment of venous hypertension. Radiologists can play an important role by recognizing signs of congestion on routine imaging, helping educate physicians who are learning point-of-care ultrasound on optimal Doppler acquisition, and incorporating venous excess ultrasound principles into their interpretive reporting.

INTRODUCTION

Systemic venous congestion is increasingly recognized as an important contributor to organ dysfunction and worse outcomes in hospitalized patients, particularly those with cardiac, renal, or critical illness[1,2]. Elevated right-sided pressures are transmitted retrogradely to the hepatic, renal, and splanchnic venous systems, resulting in impaired organ perfusion and increased interstitial pressure leading to organ-specific complications such as acute kidney injury (AKI)[2-4]. Although the pathophysiology of venous hypertension has been well described, noninvasive bedside detection remained imprecise until the introduction of structured Doppler-based frameworks[1,5,6]. Venous congestion is now viewed not only as a marker of volume or pressure overload but also as a contributor to organ dysfunction. Seminal invasive hemodynamic studies in acute decompensated heart failure suggested that elevated central venous pressure, rather than reduced cardiac output, was more closely associated with the development of AKI. Similar associations have been reported across the spectrum of cardiorenal syndromes, as well as in pulmonary hypertension and critical illness[1,5,7-9]. The kidneys, enclosed within a relatively noncompliant capsule, are particularly susceptible to venous hypertension. As renal venous pressure increases, interstitial edema ensues, filtration gradients are impaired, and an “intracapsular tamponade”-like state may develop, an entity now commonly referred to as congestive nephropathy[2,10,11].

Conventional bedside markers of congestion, including jugular venous distension, peripheral edema, pulmonary crackles, and radiographic pulmonary edema, often lack sensitivity for detecting early or subclinical venous congestion[12,13]. Notably, patients receiving dialysis may demonstrate substantial pulmonary congestion despite unremarkable lung auscultation. Biomarkers such as natriuretic peptides and chest radiography provide indirect or relatively insensitive assessments of congestion and do not fully capture its downstream organ level consequences. In contrast, ultrasonography allows a more granular assessment of hemodynamics, particularly when multiple organ systems are evaluated at the bedside by the treating physician, an approach now commonly referred to as point-of-care ultrasound (POCUS)[14-16]. Lung ultrasound sensitively detects extravascular lung water. Cardiac ultrasound identifies right and left sided structural contributors to congestion. Abdominal venous Doppler waveforms reveal the physiologic effects of elevated right atrial pressure on the hepatic, renal, and splanchnic circulations. The venous excess ultrasound (VExUS) score integrates these Doppler findings into a structured grading framework that has been associated with adverse renal outcomes, an increased risk of postoperative AKI, and morbidity and mortality in heart failure populations[6,12,17-19]. Additional studies suggest that temporal changes in VExUS are clinically meaningful. Improvement in venous Doppler patterns within the first 72 hours of hospitalization has been associated with lower mortality, enhanced diuretic responsiveness, and improved renal recovery[5,7,8]. Conversely, residual or subclinical venous congestion identified on Doppler assessment, even after apparent clinical decongestion, has been linked to early rehospitalization and increased mortality[12,17]. Taken together, these findings highlight venous congestion as a dynamic and measurable physiologic state that is frequently encountered on routine imaging studies, underscoring an important opportunity for radiologists to recognize and contextualize these Doppler patterns across both inpatient and outpatient settings.

This review outlines the VExUS framework, addresses common technical and conceptual challenges in Doppler interpretation, and illustrates how VExUS principles may be incorporated into routine radiologic reporting to improve the clinical relevance of abdominal and renal vascular examinations.

VEXUS GRADING

The VExUS system comprises four elements, namely inferior vena cava (IVC) caliber and Doppler waveforms of the hepatic, portal, and intrarenal veins. IVC measurements offer a general estimate of right atrial pressure, whereas abdominal venous Doppler findings demonstrate the downstream impact of venous hypertension on individual organs[6]. This organ level Doppler assessment underlies the clinical relevance of the VExUS framework[11,19].

IVC ultrasound

An IVC diameter of at least 2 cm serves as the initial entry criterion for VExUS grading. Although the relationship between IVC size and invasively measured right atrial pressure is imperfect, the VExUS algorithm requires IVC dilation before hepatic, portal, or intrarenal venous Doppler abnormalities are interpreted as manifestations of systemic congestion. This approach is physiologically grounded, as the vessel directly connected to the right atrium is expected to dilate first, according to its compliance, before elevated pressure is transmitted to downstream organs. Notably, the cutoff of 2 cm is derived largely from studies in Western populations and may not be directly applicable to individuals with smaller body surface area. Therefore, this threshold should not be applied rigidly when deciding whether to proceed with further Doppler assessment. In patients with a high clinical suspicion for congestion, an IVC diameter just below this cutoff (e.g., 1.8 cm) should not preclude performing the remainder of the VExUS evaluation.

Hepatic vein Doppler

The hepatic veins are in near-direct hydraulic continuity with the right atrium via the IVC. As right-atrial pressure rises and falls, those pressure changes are transmitted retrograde into the hepatic veins, modulating forward vs reverse venous flow. Normal hepatic venous flow demonstrates four distinct waveform components. Two larger antegrade waves, the systolic S wave and the diastolic D wave, represent flow toward the right atrium. Two smaller retrograde components, the A and V waves, reflect brief periods of flow away from the right atrium related to atrial contraction and end of ventricular systole respectively (Figure 1). As right atrial pressure rises, the pressure gradient driving systolic venous return decreases, resulting in progressive attenuation of the systolic S wave. With more advanced congestion, particularly in the presence of tricuspid regurgitation, which commonly accompanies volume overload due to annular dilation, the S wave may reverse and appear above the baseline. Similar waveform alterations may also be seen in conditions not directly related to elevated right atrial pressure, including cardiac arrhythmias, and therefore must be interpreted in appropriate clinical and physiologic context. Familiarity with the determinants of individual waveform components, as summarized in Figure 2, is essential, and simultaneous electrocardiographic tracing greatly facilitates accurate waveform identification.

Figure 1 Hepatic vein Doppler waveforms with electrocardiographic correlation. A: Schematic representation; B: Representative waveforms. Arrow in panel B indicates inspiratory increase in forward velocities. Figure are reproduced with permission from NephroPOCUS.com. The corresponding author (Abhilash Koratala), as the owner of the website, has authorized the use of these figures in this manuscript by all authors. P Proof of ownership can be found on the ‘About’ page of the website: https://nephropocus.com/about/.

Figure 2 Key determinants of hepatic vein Doppler waveform components. Figure is reproduced with permission from NephroPOCUS.com. The corresponding author (Abhilash Koratala), as the owner of the website, has authorized the use of these figures in this manuscript by all authors. Proof of ownership can be found on the ‘About’ page of the website: https://nephropocus.com/about/.

Portal vein Doppler

Under normal conditions, the portal vein demonstrates continuous hepatopetal flow with minimal cardiac phasicity (Figure 3A). Unlike the hepatic veins, it does not exhibit distinct S-and D-waveforms at baseline, as the portal circulation is separated from the caval system by the hepatic sinusoids, which dampen transmission of right atrial pressure. As venous pressure increases, pulsatility emerges and progressively intensifies. Mild congestion is characterized by a pulsatility fraction between 30% and 50%, defined as the percent difference between maximum and minimum velocities within a single cardiac cycle, whereas severe congestion is reflected by a pulsatility fraction exceeding 50%. For the same physiologic reason that right atrial pressure is incompletely transmitted, portal vein abnormalities typically develop after hepatic venous waveform changes and often improve earlier with decongestion, although this sequence is not universal. For example, patients with preserved right ventricular longitudinal excursion may maintain relatively normal hepatic venous waveforms despite marked portal vein pulsatility. Also, in the setting of severe chronic tricuspid regurgitation, portal vein Doppler may represent the most reliable abdominal venous marker of clinical decongestion, as hepatic venous waveforms often remain persistently abnormal, while portal vein pulsatility may decrease to below 50% with effective volume removal[6,20,21]. Measurements of portal vein pulsatility fraction can be unreliable in the presence of arrhythmias such as atrial fibrillation, where beat-to-beat variability may distort the waveform; averaging measurements across multiple cardiac cycles can provide a more representative estimate. Similarly, respiratory motion may cause the Doppler sample volume to move in and out of the vessel, producing confusing or inconsistent waveforms. Interpreting radiologists should be aware of this possibility when evaluating portal vein Doppler tracings.

Figure 3 Doppler waveform. A: Normal portal vein Doppler waveform demonstrating near-continuous flow with mild undulations above the baseline; B: Normal intrarenal venous Doppler waveform demonstrating continuous flow below the baseline with a concurrent arterial waveform above. The Doppler sample gate is positioned at the interlobar vessels, indicated by white arrows in the accompanying illustration.

Intrarenal vein Doppler

The main renal vein often demonstrates pulsatility similar to that of the hepatic veins, although to a lesser degree because of its greater distance from the right atrium. For this reason, “intrarenal” venous waveforms, typically sampled at the interlobar level, more reliably reflect renal congestion. These veins lie within the confines of the renal capsule and are particularly sensitive to changes in compliance resulting from interstitial edema and increased intraabdominal pressure, a phenomenon commonly described as “renal tamponade” in congestive states.

Under normal conditions, intrarenal venous flow is continuous and low velocity (Figure 3B). As renal interstitial and venous pressures increase, the waveform evolves to a biphasic pattern with distinct systolic and diastolic components. With severe congestion, it becomes monophasic, characterized by a single diastolic component. Although this pattern is analogous to systolic flow reversal seen in the hepatic veins, the retrograde component may be obscured by overlying arterial flow. These morphologic changes reflect rising renal interstitial pressure and are associated with impaired renal perfusion and increased susceptibility to AKI. While intrarenal venous Doppler image acquisition is technically more challenging, it may provide the most specific insight into congestive nephropathy. Interpretation in patients with chronic kidney disease, renal transplantation, or obstructive uropathy may be limited, largely due to the lack of dedicated studies in these populations.

The score

As noted above, when the IVC diameter exceeds 2 cm, further evaluation of the hepatic, portal, and intrarenal venous Doppler waveforms is performed. For grading purposes, waveform abnormalities in each vessel are categorized as normal, mildly abnormal, or severely abnormal (Figure 4). Hepatic vein Doppler is considered mildly abnormal when the systolic S wave is smaller than the diastolic D wave but remains below the baseline, and severely abnormal when systolic flow is reversed. Portal vein Doppler is classified as mildly abnormal when pulsatility ranges from 30% to 50% and severely abnormal when pulsatility is greater than 50%. Intrarenal venous Doppler is considered mildly abnormal when pulsatile with distinct systolic and diastolic components and severely abnormal when monophasic with a diastolic-only pattern.

Figure 4 Schematic illustration of normal, mildly abnormal, and severely abnormal Doppler patterns of the hepatic, portal, and intrarenal veins. Panels are displayed side-by-side to facilitate comparison of waveform evolution across severity grades. Figure are reproduced with permission from NephroPOCUS.com. The corresponding author (Abhilash Koratala), as the owner of the website, has authorized the use of these figures in this manuscript by all authors. Proof of ownership can be found on the ‘About’ page of the website: https://nephropocus.com/about/.

Grade 1, representing mild congestion, is defined by a plethoric IVC with normal or mildly abnormal venous Doppler waveforms and no severely abnormal patterns. Grade 2, corresponding to moderate congestion, is defined by IVC dilation with at least one severely abnormal venous Doppler waveform. Grade 3, representing severe congestion, is defined by IVC dilation with two or more severely abnormal venous Doppler patterns (Figure 5). Among these categories, VExUS grade 3 has been most strongly correlated with AKI, while grades 2 and 3 have also been associated with adverse outcomes across multiple patient populations[4,6,10,21]. The value of VExUS extends beyond quantifying venous congestion to tracking the physiologic response to decongestive therapy. Serial improvement in venous Doppler waveforms provides a visual marker of effective volume removal with interventions such as diuresis. Figure 6 demonstrates a representative case in which VExUS findings improved in parallel with fluid removal, accompanied by resolution of hyponatremia and AKI.

Figure 5 Venous excess ultrasound grading system. Figure are reproduced with permission from NephroPOCUS.com. The corresponding author (Abhilash Koratala), as the owner of the website, has authorized the use of these figures in this manuscript by all authors. Proof of ownership can be found on the ‘About’ page of the website: https://nephropocus.com/about/. VExUS: Venous excess ultrasound.

Figure 6 Serial venous Doppler waveforms demonstrate stepwise improvement, from top to bottom, in a patient with acute kidney injury and hyponatremia, accompanied by parallel improvement in serum sodium and creatinine levels. As shown, recovery of portal venous flow typically precedes normalization of hepatic and intrarenal venous waveforms, while renal venous abnormalities may persist longer due to residual interstitial edema. Na: Serum sodium; AP: Assessment and plan; S wave: Systolic wave; D wave: Diastolic wave. Citation: Koratala A, Ronco C, Kazory A. Multi-Organ Point-Of-Care Ultrasound in Acute Kidney Injury. Blood Purif 2022; 51: 967-971. Copyright © 2022, © 2022 S. Karger AG, Basel. Published by Karger Publishers. The authors have obtained the permission for figure using from the Karger Publishers (Supplementary material).

TECHNICAL PITFALLS

Accurate VExUS assessment hinges on high-quality venous Doppler acquisition and interpretation. Many perceived limitations reflect unrecognized technical pitfalls rather than physiologic complexity, particularly in point-of-care practice and, to some extent, in radiology.

A key limitation is the lack of electrocardiography (ECG) gating during abdominal Doppler acquisition. This issue is particularly relevant when interpreting hepatic vein Doppler waveforms, which rely on comparison of the relative amplitudes of the systolic and diastolic components. In the absence of ECG gating, reliable distinction between the S and D waves is not possible, regardless of how classic the spectral tracing may appear. The S wave follows the R wave of the ECG, the D wave follows the T wave, and the A wave corresponds to the P wave as illustrated in Figure 1. ECG correlation is particularly valuable in the presence of arrhythmias, where changes in hepatic vein waveforms may reflect rhythm-related phenomena rather than elevated right atrial pressure. It also aids interpretation when the physiologic determinants of individual waveform components (see Figure 2) must be integrated with the broader clinical context, and in situations where patients are unable to hold their breath limiting acquisition of a continuous Doppler tracing across multiple consecutive cardiac cycles[1,9,22-24]. Even for portal vein Doppler, simultaneous ECG tracing facilitates differentiation between true cardiac pulsatility, and flow interruptions caused by respiratory motion at the same sampling gate. In intrarenal venous Doppler, the accompanying arterial waveform often serves as an intrinsic timing reference, effectively functioning as a surrogate ECG and allowing easier identification of cardiac cycle phases. When renal venous flow is recorded without a concurrent arterial signal, ECG correlation remains valuable for accurate interpretation[22].

In addition, Doppler parameters require deliberate optimization. When the Doppler scale is set too high for a given vascular bed, color flow may not be visualized, leading to the erroneous impression of reduced flow or thrombosis. On pulsed-wave Doppler, this is associated with a low-amplitude waveform, limiting reliable qualitative assessment. Conversely, an excessively low scale produces aliasing, seen on color Doppler as a mosaic of colors that may falsely suggest high-velocity turbulent flow and mimic stenosis; on spectral Doppler, this appears as truncation of the waveform with signal wrapping to the opposite side of the baseline[22,23]. For this reason, expert practice generally favors scale settings of approximately 40 cm/second for hepatic and portal vein sampling and around 20 cm/second for intrarenal venous Doppler, with adjustments as needed[22]. Similarly, overly aggressive wall filter settings may eliminate diagnostically important venous components of the waveform. Although manual angle correction is routine for trained sonographers, it may be less familiar to point-of-care users. Importantly, because VExUS assessment is based on qualitative waveform features such as relative amplitudes and pulsatility rather than absolute velocity measurements, dependence on precise angle correction is reduced. This provides practical flexibility for point-of-care clinicians, particularly in time-constrained settings where fine-tuning the insonation angle may not be feasible.

LIMITATIONS OF VEXUS

Despite growing clinical interest, several limitations of the VExUS framework warrant consideration. Much of the available evidence linking VExUS to renal outcomes and mortality is observational, and causality cannot be definitively established. Prospective interventional studies evaluating whether VExUS-guided management improves clinical outcomes remain limited.

Physiologic confounders may also influence how these findings are clinically integrated. Clinicians must recognize when normalization of Doppler waveforms is a realistic therapeutic target and when it may not be. For example, in severe pulmonary hypertension with significant tricuspid regurgitation, hepatic vein waveforms may remain abnormal despite appropriate management. Attempting to normalize these patterns solely through aggressive fluid removal may reduce forward flow and potentially lead to organ injury. Mechanical ventilation, particularly with high positive end-expiratory pressure, can also alter venous Doppler waveforms and should be considered during interpretation. Importantly, organs do not “care” why congestion occurs; what matters is whether it can be relieved. Decongestion may be achieved through several mechanisms, including reduction of right-sided pressures (e.g., pulmonary vasodilators), improvement in cardiac pump function (e.g., inotropes), and/or volume removal when appropriate. While radiologists can help by identifying and reporting the presence and severity of venous congestion, the clinical integration of these findings and selection of the most appropriate therapeutic strategy ultimately rests with the treating clinician.

Reproducibility, while improving with standardized protocols, remains dependent on operator training and acquisition technique. Recent prospective validation studies have shown moderate to good interobserver agreement (κ approximately of 0.6-0.8 among experienced operators), particularly when ECG guidance is used[25]. However, generalizability across different practice settings is still being evaluated. This limitation is most relevant when images are acquired by trainee sonographers or clinicians early in their POCUS experience who may subsequently seek radiology input for interpretation.

Finally, systemic venous congestion represents only one component of complex cardiorenal and critical illness physiology. Reduced cardiac output, neurohormonal activation, and intra-abdominal pressure may contribute independently or synergistically to organ dysfunction. Accordingly, VExUS should be interpreted as part of a broader hemodynamic assessment rather than as a standalone diagnostic tool.

RADIOLOGY IMPLICATIONS

Radiologists occupy a pivotal yet often underrecognized role in the early detection of venous congestion. Abdominal vascular Doppler studies are frequently performed for indications unrelated to heart failure, including abnormal liver enzymes, abdominal pain, renal dysfunction, or lower extremity edema. This places radiologists in a position to identify Doppler patterns of congestion before clinical suspicion arises. When these findings are not explicitly characterized, opportunities for timely hemodynamic intervention may be missed.

Traditional radiology reports often emphasize vascular patency while providing limited interpretation of venous waveform morphology. Descriptors such as “hepatopetal flow present” or “no hepatofugal flow” confirm flow direction but do not convey the hemodynamic significance of systolic blunting or abnormal pulsatility. Similarly, reporting femoral venous flow as “phasic” or “present” does not distinguish normal respiratory variation from pathologic cardiac related pulsatility. In renal Doppler examinations, interpretive focus frequently remains on resistive indices, despite growing evidence that intrarenal venous Doppler patterns provide important prognostic insight.

Incorporation of VExUS principles into radiology reporting is both feasible and clinically meaningful. Hepatic venous systolic blunting or reversal, particularly when interpreted with ECG correlation, may be described as suggestive of elevated right-sided cardiac pressures. Marked portal venous pulsatility can be noted as exceeding normal physiologic variation and consistent with significant venous congestion. Monophasic intrarenal venous flow may be highlighted as a marker of severe renal venous hypertension and an imaging pattern associated with increased risk of AKI across multiple clinical settings. In addition to the classic VExUS veins, radiologists may identify congestion in other systemic veins, including the splenic or femoral veins, during abdominal or deep vein thrombosis examinations and recommend further cardiovascular evaluation, such as echocardiography, to clarify the hemodynamic context and guide management decisions[26,27].

As VExUS terminology gains wider clinical adoption, explicit radiologist commentary facilitates integration of Doppler findings into comprehensive hemodynamic assessment. Beyond reporting, radiologists can play an important role in education as interest in POCUS continues to expand across specialties. While basic image acquisition is increasingly decentralized, reliable venous Doppler acquisition and interpretation remain technically demanding and require precise probe positioning, appropriate insonation angles, optimized spectral parameters, and electrocardiographic correlation when feasible. Radiology-led multidisciplinary teaching and quality assurance initiatives can help ensure reproducible acquisition, accurate waveform interpretation, and physiologically grounded application of VExUS across clinical environments, reinforcing radiology’s essential role in contemporary hemodynamic assessment.

EXAMPLE STRUCTURED REPORTING LANGUAGE

IVC

Maximal diameter 2.4 cm (collapsibility < 50%, where available; routine abdominal studies may not include a dedicated collapsibility clip).

Hepatic vein Doppler

Systolic wave reversal.

Portal vein Doppler

Pulsatile waveform with pulsatility fraction approximately 60%.

Intrarenal Doppler

Monophasic (diastolic) venous pattern with increased stasis index. Arterial resistive index 0.8.

Other veins

Femoral vein Doppler demonstrates a pulsatile waveform with increased stasis index.

Interpretation

Findings are suggestive of VExUS grade 3, consistent with severe systemic venous congestion. Clinical correlation is recommended, with further hemodynamic evaluation where appropriate.

CONCLUSION

Venous congestion appears to be an important and potentially modifiable contributor to organ dysfunction across cardiovascular, renal, and critical care settings. The VExUS framework enables structured, noninvasive assessment of venous hypertension using abdominal Doppler findings that extend beyond conventional markers of congestion. Radiologists play a key role in recognizing these patterns on routine studies, improving Doppler acquisition and reporting, and supporting multidisciplinary adoption of VExUS to enhance hemodynamic assessment and clinical decision making.