Episode 16: Are you sure you want that scan?

by Bob Stuntz in , , , ,


We have all answered that call from radiology or a radiology tech.  In this episode, we talk about the myths and truths behind the use of oral contrast in the ED, ED imaging in pregnancy, and contrast induced nephropathy.

1. Oral Contrast in the ED: With new generation scanners, most patient with non traumatic abdominal pain do not need oral contrast.  Multiple studies have shown that with new generation scanners, CT for appendicitis does not suffer when oral contrast is not administered. In high grade bowel obstruction, the American College of Radiology (ACR) actually says we should NOT be giving oral contrast as it is bad for the patient (potential aspiration), and may obscure radiologic evidence of bowel wall ischemia.  With motion artifact reduction in new generation scanners, it really isn't adding much to diverticulitis, either.  

2. Imaging in pregnancy: Remember this is all about how we communicate risk.  We always want to follow the ALARA (as low as reasonably achievable) principle, but we must not punish the patient for being pregnant by not doing the appropriate study.  CT versus VQ is controversial, but I feel this guideline from the American Thoracic Society/Society of Thoracic Radiology is a reasonable approach:

http://pubs.rsna.org/doi/full/10.1148/radiol.11114045?sid=5d035f90-90f2-4dc5-b993-d57ed0e0317b

http://pubs.rsna.org/doi/full/10.1148/radiol.11114045?sid=5d035f90-90f2-4dc5-b993-d57ed0e0317b

Abdominal imaging can be tricky, but the answer should generally be US first in the pregnant patient, followed by MRI if possible.  Again, if they need the CT, discuss the risk/benefit ratio and educate your patients.  

3. Contrast Induced Nephropathy (CIN): The incidence of CIN is likely lower than we thought previously.  In general patients with a GFR < 30 are at highest risk, and those with a GFR between 30-45 may be at higher risk.  The majority of are patients, however, are at a minimal risk of CIN.  To prevent it in high risk patients, the best we can try is hydration with isotonic fluids and educate the patients.  But again, if you need the scan, you need the scan.   

Listen to the podcast, and let me know what you think!