Being radiopaque may be diffuse or focal.
Common causes of stool being diffusely radiopaque:
(1) radiographic contrast material
(2) iron replacement therapy
(3) bismuth subsalicylate (Pepto Bismol)
Less common causes of stool being radiopaque:
(1) mercury, lead, arrsenic or other heavy metals
(2) meconium
(3) sand or clay
(4) iodide
(5) chloral hydrate
(6) carbon tetrachloride
Causes of focal radiopaque material:
(1) intestinal transit markers
(2) foreign bodies (metal, glass, other)
(3) animal and some fish bones
(4) enteric-coated or slow-release medications
(5) many medications
(6) gravel
Interestingly aluminum is radiolucent and not radiopaque,
Refernces:
