I shared this image on Twitter (X), asking to identify the anechoic area marked with an arrow. On the left side, there’s an M-mode image showing the long axis view of the dilated inferior vena cava (IVC), measuring 2.7 cm in diameter. On the right, you can see a transverse scan in the epigastric region displaying a few anechoic structures.

Out of 312 respondents, 63% thought it was a transverse view of the plethoric IVC, but it’s not. It’s actually the gall bladder.

The purpose of this poll is to urge POCUS users to consider normal anatomy first before jumping to pathology. Upon closer inspection, you can observe distinct IVC and aorta anterior to the vertebral shadow, and the anechoic round area is separate from them, attached to the liver. Additionally, by paying attention to the scale on the right of the image, you can see that the anechoic area measures about 5 cm, significantly larger than the IVC diameter measured in the long axis. In the image below, you can observe the transition to the long axis view of the gall bladder, and also an anatomical illustration and labeled image.