Consider the Probe

Consider the Probe: Can’t See the IVC – August 12, 2026

Michael Hohl MD

A patient comes to the ED and febrile, hypotensive, and with a history of unspecified “heart

problems.” They’re in your resuscitation bay and you have to make the decision, can we safely

treat this patient for hypotension and possible sepsis with IV fluids? Naturally, you reach for the

ultrasound attempt to visualize the IVC but the patient’s body habitus and abdominal distention

prevent you from getting an adequate window. The bedside RN prompts you that the blood

pressure is still low. So, what do you do now?

Inferior Vena Cava for Volume Assessment

The traditional approach to volume assessment in the emergency department using

point-of-care ultrasound relies on visualizing the inferior vena cava (IVC) at the cavoatrial

junction with the right atrium and the hepatic vein. At this point the IVC is visualized

longitudinally and assessed for distensibility (IVC diameter, centimeters) and respirophasic

variation (IVC collapsibility, percentage).

IVC Volume Assessment Parameters

• IVC diameter <2.5 cm and >50% collapsibility → low RAP, euvolemic to hypovolemic

(can tolerate fluids)

• IVC diameter >2.5 cm and <50% collapsibility → high RAP, hypervolemic (fluid may not

benefit and/or cause harm) [1]

This exam demonstrated a sensitivity of 85.7% and specificity of 86.4%. However, when you are

unable to effectively visualize the IVC or have poor windows to accurately assess these

parameters, alternatives exist to help estimate right atrial pressure (RAP) and overall volume

status.

Internal Jugular Vein for Volume Assessment

The internal jugular vein (IJV) has been shown to exhibit similarly measurable distensibility

metrics to the IVC for volume status assessment. There are two methods to obtain these

measurements. The quick and dirty method involves visualizing the IJV in transverse and, with

the patient sitting at 30-45 degrees, have them perform a Valsalva maneuver. The diameter is

measured pre- and post-Valsalva.

IJV-Valsalva Volume Assessment Parameters

• IJV diameter increased >17% → low RAP, euvolemic to hypovolemic (can tolerate fluids)

• IJV diameter increased <17% → high RAP, hypervolemic (fluid may not benefit and/or

cause harm) [2]

This exam demonstrated a 90% sensitivity and 74% specificity for elevated RAP with a 94%

negative predictive value. A more comprehensive IJV assessment exists in which you factor in

right atrial depth to better estimate RAP but requires more time and adequate parasternal long

axis views [3].

Common Femoral Vein Doppler for Volume Assessment

Assessing doppler flow through the common femoral vein (CFV) has also been proposed as a

surrogate for IVC diameter in volume assessment. The study was conducted amongst a patient

population of patients with underlying heart failure, so results may not be generalizable but were

promising as an alternative option nonetheless. The CFV is visualized just superior to greater

saphenous entrance in the long axis and pulse wave doppler with angle correction is placed

along the length of the vessel.

CFV Doppler Volume Assessment Parameters

• No pulsatility, flat venous wave → high negative predictive value (89%) for decreased

TAPSE

• Pulsatile, clear waveform → high correlation coefficient for IVC >2cm (r = 0.831) with

95% sensitivity, 90% Specificity

The biggest take away from this study is that CFV pulsatility is strongly statistically associated

with IVC size in patients in acute heart failure [5]. While this study lacks power (N=74) and

generalizability, when the traditional IVC view is unattainable, the CFV doppler may be a viable

option to aid in clinical decision making.

References

1. Dunfield R, Ross P, Dutton D, et al. SHoC-IVC: Does assessment of the inferior vena

cava by point-of-care ultrasound independently predict fluid status in spontaneously

breathing patients with undifferentiated hypotension?. CJEM. 2023;25(11):902-908.

doi:10.1007/s43678-023-00584-1

2. Simon MA, Kliner DE, Girod JP, Moguillansky D, Villanueva FS, Pacella JJ. Detection of

elevated right atrial pressure using a simple bedside ultrasound measure. Am Heart J.

2010;159(3):421-427. doi:10.1016/j.ahj.2010.01.004

3. Istrail L, Stepanova M. Novel point-of-care ultrasound (POCUS) technique to modernize

the JVP exam and rule out elevated right atrial pressures. medRxiv

2021.10.14.21264891; doi: https://doi.org/10.1101/2021.10.14.21264891

4. Torres-Arrese M, Mata-Martínez A, Luordo-Tedesco D, et al. Role of the femoral vein

doppler in acute heart failure patients: results from a prospective multicentric study. Rev

Clin Esp (Barc). 2023;223(6):359-365. doi:10.1016/j.rceng.2023.04.004

5. Prats M. Femoral Vein Doppler in Heart Failure. Ultrasound G.E.L. Podcast Blog.

Published on July 31, 2023. Available at https://www.ultrasoundgel.org/148.