This patient has a caecum which is not retroperitoneal and is therefore 'mobile' and susceptible to twisting or folding. The 'volvulus' (twist/fold) has resulted in dilatation of the caecum.
The caecum is grossly dilated and is no longer located in its anatomical position, the right iliac fossa (RIF), which is occupied by small bowel in this example.
The caecum is grossly dilated and is not located in the RIF which is occupied by small bowel.
Radiology Masterclass 'Caecal Embryo Sign'
In caecal volvulus, the dilated caecum takes on a shape similar to a mammalian embryo. That is, the formation of a large dilated caecal pole (head), with one or two further 'segments' (body and tail). This is seen in all the images on this page.