OK, ok, I said it was a tricky case.

First note that for probably the first time in the over 3500 images in www.TheFetus.net I did not crop the image to remove all the technical data as I usually do. From that information you can see that all images were obtained with the same transducer. Also note that I changed the question from

What is (are) the finding(s) and diagnosis ?

to:

What is (are) the anomaly on the images, and what does it signify  ?

Although the meaning of the two sentences could be the same...  I was actually asking what was the anomaly on the images!

Finally to make the finding more obvious, let me show a superimposition of the first four images (I simply summed a faded copy of the 4 images on top of each other to make the common element more obvious)

and the last 2:

Now the problem is more obvious !

Findings:

• There is a shadow arising from the very top of the images
• The shadow remains in the same place on all images, regardless of magnification or anatomical structure (thus moving the transducer around on the patient does not simply dislodge a small bubble of gas between the face of the transducer and the patient"s skin.
• The acoustic shadow is less pronounced at greater depths then shallow depths.

This is an X-ray of a transducer (an old one !). The piezoelectric crystals make a thin line on the surface of the transducer below the impedance matching compound.

These findings are due to a lack of information collected by the transducer at the level of the acoustic shadow. Since the artifact remains in the same position, it means that it originates from the transducer. In the majority of cases this is due to an acoustic decoupling of the piezoelectric elements. In other words: someone dropped the transducer and broke it ! Broken transducers are easy to recognize: the same shadow persist from image to image and also from patient to patient !

(Some of these images are from a forthcoming lecture on Pitfalls & Artifacts)