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 ALiEM (PV) Cards for more resources.

Michelle Lin, MD
ALiEM Founder and CEO
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 SF General. ALiEM Founder @aliemteam #PostitPearls at https://t.co/50EapJORCa Bio: https://t.co/7v7cgJqNEn
Michelle Lin, MD