Radiolucent gallstones


Acute right upper quadrant pain and fever are very suspicious for choledocholithiasis. But always remember about radiolucent gallstones that are isodense to bile and may not be identified on x-ray or CT, as in this case. 

So, if gallstones on CT are not seen, then other modalities such as US, MRI or ERCP should be considered, which are more sensitive for calculi.