Contrast Studies and Special Radiographic Procedures
Contrast Studies and Special Radiographic Procedures
This domain tests contrast media selection, patient preparation, and procedure-specific risks. Expect barium versus iodinated contrast, fluoroscopic studies, and safe practice.
Core rules
- Barium sulfate is inert and gives excellent GI coating, but it is contraindicated when perforation is suspected because it causes peritonitis.
- Water-soluble iodinated contrast is used for suspected perforation, urinary tract studies, vascular studies and CT. Ionic agents are more hyperosmolar; non-ionic agents are better tolerated.
- Check renal function, allergy history, pregnancy and hydration before iodinated contrast. Follow local policy for metformin and thyroid risk.
- Common studies: barium swallow/meal/follow-through/enema, IVU/CT urography, HSG, myelography and DSA.
- Fluoroscopy increases dose; collimate, use pulsed fluoroscopy and keep screening time short.
Worked example
A patient with suspected duodenal perforation needs a contrast study. Barium is unsafe because leakage into the peritoneum causes chemical peritonitis. Use a water-soluble iodinated agent, which is absorbed and less harmful if it leaks; document the choice and monitor the patient.
Traps
- Giving barium when perforation or obstruction is suspected.
- Ignoring renal function before iodinated contrast.
- Forgetting consent and allergy history.
- Screening continuously instead of using short pulses.