In the last post, we talked about IVC views. You might be wondering, “Why so many posts about the inferior vena cava?” Well, here’s the thing—I’m all for advanced hemodynamics like cardiac Doppler and VExUS. But let’s be honest: if you can’t confidently identify and interpret the IVC, the rest of it doesn’t matter much. Misidentifying the IVC for adjacent structures happens more often than you’d think, especially when working with trainees at different stages of learning. It’s a simple yet critical part of hemodynamic assessment that often gets overlooked or undermined.

The aorta is the most commonly mistaken structure for the IVC among POCUS users. In an earlier post, we covered key differences between these vessels and debunked the myth that the IVC isn’t pulsatile. However, there are a couple of additional points worth emphasizing. To illustrate this, I recently shared a quiz on Twitter featuring subxiphoid images with two anechoic structures and asked respondents to identify them. Surprisingly, only about half answered correctly that neither structure was the IVC. The two structures in question were actually the aorta and the stomach.

If you’re given a still image instead of a video clip, can you still identify these structures? Absolutely—that’s the beauty of understanding anatomy. Remember, the IVC is attached to the liver, whereas the aorta is separated from it by connective tissue. Take a closer look at Image A. You’ll notice a distinct “gap” between the vessel and the liver (focus on the area closer to the heart, not towards the pelvis). This gap indicates it’s not the IVC. The only large blood vessel adjacent to the IVC is the aorta, so this must be the aorta. Now, for Image B: The structure here is closer to the liver, but instead of a significant portion of liver, you only see its tip, which appears somewhat triangular. Additionally, the structure isn’t as tubular as a vessel, and if you look closely, you can spot a feeding tube within it. This identifies it as the stomach. Below, I’ve included anatomy illustrations and another example highlighting the “gap” mentioned above for clarity.

Here’s another key distinction between the aorta and the IVC. I shared the first image below in a quiz, and many thought it was the IVC. However, the image clearly shows the vessel crossing the diaphragm and passing behind the heart in the chest. If you recollect the anatomy, IVC enters the right atrium at the level of the diaphragm and does not pass behind the heart. Therefore, the structure shown is aorta.

The next two images are from the same patient and show the IVC, which is nearly completely collapsible with inspiration, along with a clip demonstrating the aorta-IVC transition.

Here’s another common pitfall: confusing the right hepatic vein (RHV) with the IVC. While individual anatomy can vary, oblique views (see how my hand is positioned on the CT image below – pointing to left shoulder) make this error more likely. If the “IVC” you’re observing seems unusually small, has a wide mouth (= the HV-IVC junction near the right atrium), and is surrounded by a lot of liver, suspect you might actually be looking at the RHV. While the IVC also has liver adjacent to it, most of the liver is situated anterior to the vessel, with only a small portion positioned posteriorly that too depending on the angle of the beam. To avoid this mistake, aim to keep your beam straight without excessive rotation. This distinction is critical—I’ve seen situations where operators mistakenly focused on the RHV and couldn’t locate an ECMO guidewire, which was already in the IVC. Such confusion can lead to unnecessary delays during life-saving procedures.

Below is another nice example

Here’s a great clip from our anesthesia friends demonstrating how various probe movements reveal different structures.

So next time you’re performing IVC ultrasound, keep this in mind and pass these tips along to your trainees or peers who might not yet follow nephropocus.com 😊. I hope this post proves helpful!