Barium sulfate

Barium sulfate (BaSO4), often just called barium in radiology parlance, is a salt of barium, a metallic chemical element with atomic number 56. Barium is considered one of the heavy metals. Unlike barium and many of its other salts, barium sulfate is insoluble in water and therefore very little of the toxic barium metal is absorbed into the body.

It is the preferential contrast agent for gastrointestinal (GI) fluoroscopic examinations 2 due to its high attenuation of x-rays, lack of absorption, and lack of toxicity. It can also be found in some oral contrast preparations used for CT. 

Barium can be mixed into high-density or low-density suspensions. Both suspensions typically attenuate x-rays more than water-soluble contrast. High-density barium is preferred over water-soluble contrast for fine-detail evaluation of the gastrointestinal system (e.g. evaluation for early changes from Crohn disease). Suspensions created for CT use are very low density.

Due to its insolubility in water, barium sulfate contrast media are supplied as fine particles of the barium sulfate suspended in water. Often artificial flavourings are added to make the mixture more palatable.

Its allergy profile is favourable with very few reported reactions 1. Historically, allergy was more common when excipients, such as chocolate, were used 1.

  • known or strongly suspected gastrointestinal perforation
    • may be used in evaluation for possible oesophageal perforations, see below
  • large volume aspiration
  • prior allergic reaction (rare) 
  • left-sided colonic obstruction (relative contraindication)
    • if the barium cannot exit the colon, it has the potential to become inspissated and very hard, leading to a quite problematic constipation

Barium is thought to cause a peritonitis if it leaks into the peritoneal space. If bowel perforation is suspected, water-soluble contrast is generally preferred 3.

Similarly, barium is thought to cause a pleuritis and/or mediastinitis if it leaks into these spaces. The initial work establishing a relationship between barium and pleuritis was performed in cats and the analogy extended to humans 4. Whether the mediastinitis and pleuritis is dose-dependent is unclear. When looking for an esophageal tear, barium is safe to use after ruling out a large leak with water soluble-contrast 5.

Barium is not toxic to the airways (unlike hyperosmolar water-soluble contrast), and in the past it has even been used to create bronchograms 6. Barium does, however, have the potential to plug the distal airways, diminishing the capacity for gas exchange, so inhaling more than a small amount is not encouraged.

Barium migration into the bloodstream has the capacity to cause fatal emboli, although it is incredibly rare if the contrast is used appropriately 7.

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Article information

rID: 55948
Synonyms or Alternate Spellings:
  • Barium sulphate
  • Barium contrast medium
  • Barium contrast
  • Barium contrast agent
  • Barium contrast media
  • Barium contrast agents
  • Barium sulphate contrast

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