The Tooth Fairy. The Easter Bunny. Two cardiologists trying to agree on a JVP measurement.
These are myths we share with children — and, perhaps, with medical students. When it comes to estimating right atrial pressure, maybe it’s time we add JVP to that list.
A study in Chest showed that clinical JVP assessment has a sensitivity of 43% and specificity of 68% — not much better than a coin toss. And in more than one-third of patients, the jugular vein simply isn’t visible on exam.
So what’s the alternative? Enter ultrasound evaluation of the IVC.
Seriously, who cares?
Think about your last ED shift where you didn’t order a fluid bolus. Hard to remember, right?
Volume status plays a role in shock, heart failure, and tamponade. But assessing fluid responsiveness is complex. No single test has all the answers, and IVC ultrasound does not predict fluid responsiveness in isolation.
Instead, it’s most powerful when integrated with the whole picture: vitals, exam, LV/RV function, and lung PoCUS.
Clinical Utility
A plethoric IVC with minimal respiratory variation has an excellent sensitivity (95-97%) for cardiac tamponade, making it useful as a rule-out tool – with the important caveat of the severely volume deplete patient.3 It has also been shown to aid in diagnosing acute decompensated heart failure.4 Additionally, a randomized controlled trial in Critical Care Medicine found that in cases of undifferentiated shock, adding PoCUS improved diagnostic accuracy by 30% — from 50% with clinical judgment alone to 80% with PoCUS.5 Once again, no test replaces the clinical picture — but the IVC remains a core component of the RUSH exam, helping us rapidly categorize undifferentiated hypotension at the bedside.
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Tamponade: A plethoric IVC with minimal variation is highly sensitive (95–97%) for tamponade — though beware in the severely volume-deplete patient.
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Heart failure: IVC assessment helps diagnose acute decompensated heart failure.
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Undifferentiated shock: In an RCT, adding PoCUS to clinical judgment improved diagnostic accuracy by 30% (50% → 80%).
Bottom line: IVC assessment doesn’t replace your clinical judgment, but remains a cornerstone of the RUSH exam.
How to IVC Ultrasound
Probe: Phased array (cardiac) probe. Alternative: Curvilinear, reverse marker orientation
Position: Supine
Placement: Just below xiphoid, angled slightly cranial
Orientation: Marker toward the head
View: Start with subxiphoid cardiac, then angle rightward to see the IVC entering the right atrium.
Measurement
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Where: ~2 cm distal to the right atrium, before hepatic vein entry
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How: Leading-edge to leading-edge, end-expiration
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Sniff test: Ask patient for a quick sniff, then visually estimate collapse
Report Two Values
- IVC size: ≥ 2.1 cm or < 2.1 cm
- Collapsibility: > 50% vs < 50%
Interpretation Examples
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Small IVC (1.7 cm) + >50% collapse → Low RA pressure
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Large IVC (>2.1 cm) + minimal collapse → High RA pressure (think CHF, PE, tamponade)
Pitfalls
- Aorta vs IVC
- The aorta can be confused with the IVC, especially in long-axis views. The aorta is more pulsatile, thicker-walled, and lies left of midline — but these differences can be subtle. This is why it’s essential to follow the IVC all the way to where it empties into the right atrium. Confirming this connection helps ensure you’re assessing the correct vessel.
- Cylinder Effect
- The IVC is a 3D structure, and probe angle matters. Think of it like ultrasounding a pop can when you’re perfectly centered, the can appears wide; shift off to the side, and it suddenly looks much narrower. This “cylinder effect” can lead to false impressions of collapsibility or dilation. That’s why it’s important to sweep through the IVC in long axis to assess its true caliber and variation.
Final Thoughts
No single PoCUS finding should guide resuscitation in isolation — but IVC ultrasound, used alongside other clinical data, is an indispensable part of your bedside toolkit.
As this is my last PoCUS Pearl of residency, thank you all for following along! Stay tuned — the series will return with Dr. Thariq Badiudeen taking the lead. Expect more pearls, more heat, and plenty of dad jokes.
References
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Vinayak, A. G., Levitt, J., Gehlbach, B., & Pohlman, A. S. (2006). Usefulness of the external jugular vein examination in detecting abnormal central venous pressure in critically ill patients. Chest, 130(4), 857–862. https://doi.org/10.1378/chest.130.4.857
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Brennan, J. M., Blair, J. E., Goonewardena, S., Ronan, A., Shah, D., Vasaiwala, S., Brooks, E., Levy, A., Kirkpatrick, J. N., & Spencer, K. T. (2007). A comparison by medicine residents of physical examination versus hand-carried ultrasound for estimation of right atrial pressure. The American Journal of Cardiology, 99(11), 1614–1616. https://doi.org/10.1016/j.amjcard.2007.01.037
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Alerhand, S., & Carter, J. M. (2019). What echocardiographic findings suggest a pericardial effusion is causing tamponade? The American Journal of Emergency Medicine, 37(2), 321–326. https://doi.org/10.1016/j.ajem.2018.11.013
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Yampolsky, S., Kwan, A., Cheng, S., & Kedan, I. (2024). Point of care ultrasound for diagnosis and management in heart failure: A targeted literature review. POCUS Journal, 9(1), 117–130. https://doi.org/10.24908/pocus.v9i1.16795
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Jones, A. E., Tayal, V. S., Sullivan, D. M., & Kline, J. A. (2004). Randomized, controlled trial of immediate versus delayed goal-directed ultrasound to identify the cause of nontraumatic hypotension in emergency department patients. Critical Care Medicine, 32(8), 1703–1708. https://doi.org/10.1097/01.ccm.0000133017.34137.82
