Contrast media

Author: Mikael Häggström

Intravenous

CT

Main article: CT with IV contrast

CT with IV contrast

Contrast medium reaction

Main article: Contrast medium reaction

In a more severe reaction:

• Adrenaline shot, 0.3-0.5mg in adults, given intramuscularly.
• Summon an anesthesiologist

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Prevention

Main article: Prevention of contrast medium reaction

Before a contrast CT of a patient with known allergic-like or unknown-type of contrast reaction to the same class of contrast medium (such as iodinated), the American College of of Radiology recommends premedication with a glucocorticoid, preferably starting 12 or 13 hours before contrast administration.

In low renal function

Main article: CT with IV contrast in low renal function

Decreased renal function and several other conditions increase the risk of contrast-induced nephropathy, which is a potentially lethal renal injury to the kidney following intravenous radiocontrast.

Peroral

• 

  Peroral contrast

Rectal

Projectional radiography and fluoroscopy

Choice of contrast medium

• Barium sulfate is generally used.
• An iodine-based contrast medium is used where there is a risk perforation, where barium may cause chemical inflammation.<

However, 1-2% of oral iodine is absorbed in the gastrointestinal tract, and can potentially case a contrast medium reaction. Also, it is more expensive than barium

Iodine-based

Recommended concentration:

Adults: 70 mg iodine per ml, such as 240 ml of a 370mg/ml solution in 1,000 mL of tap water.

Children over 5 years: 55 mg iodine per ml such as 90 ml of a 370mg/ml solution in 500 mL tap water.

CT scans

Rectally administered contrast is indicated in cases where a suspicion remains of penetrating trauma to the colon where an initial CT shows no reason for immediate surgery.