What do annotation arrows indicate?
Air along the wall of this hollow viscus in right hypochondrium. Probably pneumotosis intestinalis or emphysematous cholecystitis.
Sonographer noticed some dirty shadowing in gall bladder fossa, and his all efforts to clearly visualize GB lumen failed. What may be the cause?
Emphysematous cholecystitis should be considered. Another differential is porcelain gall bladder.
Erect chest x-ray done to look for free gas under the diaphragm.
There is no free gas under the diaphragm. In the right upper quadrant, there is an air-fluid level with a curvilinear lucency visible around the fluid component (see Series 2, annotated).