HeadCTbleedThe ideal clinical decision tool has a sensitivity and specificity of 100%.

You need a high sensitivity to be sure that your negative result indeed predicts a true negative. That means if your clinical decision tool suggests that you don’t need to get a head CT, then your head CT would have been normal.

On the flip side, this realistically means there is a low-moderate specificity. That means a clinical decision tool with at least 1 positive criterion does not always mean that there will be an abnormal finding on head CT.

There are 3 major clinical decision rules that I’ve heard tossed around in the literature:

  • Canadian CT Head Rules (CCHR)
  • New Orleans Criteria (NOC)
  • National Emergency X-Radiography Utilization Study (NEXUS)-II

There is no perfect tool.

Take a look at these decision rules and their inclusion criteria.

  • The CCHR included patients with GCS 13-15. The NOC initially enrolled only patients with a GCS of 15.
  • All factor in age (≥65 years for CCHR and NEXUS-II; ≥60 years for NOC).
  • Interestingly only the CCHR, for better or worse, take into account mechanism of injury. I’m not sure I would obtain a head CT on a pedestrian with a graze wound on the foot from a slow-moving vehicle.

Which do you use? I use a combination of all 3 and my clinical gestalt.

PV Card: Head CT in Trauma – Clinical Decision Tools

Go to the ALiEM Cards site for more resources.

Michelle Lin, MD
ALiEM Editor-in-Chief
Professor and Digital Innovation Lab Director
Department of Emergency Medicine
University of California, San Francisco
Michelle Lin, MD


Professor of Emerg Med at UCSF-Zuckerberg San Francisco General. Founder of ALiEM @aliemteam #PostitPearls https://t.co/7v7cgJqNEn
Michelle Lin, MD