Clinical Reasoning Skills

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Errors in Diagnosis

Errors in diagnosis occur in three ways:

  • Wrong diagnosis

  • Missed diagnosis

  • Delayed diagnosis

The most common cognitive errors include:

  • Premature closure (failure to continue considering reasonable alternatives after an initial diagnosis was reached)

  • Faulty context generation (inappropriately selecting prior cases for comparison)

  • Misjudging the salience of findings (missing key positive and negative findings)

  • Faulty perception (failure to properly interpret the findings)

  • Problems in the use of heuristics (not using or improperly using a 'rule of thumb')

Diagnostic errors are not always cognitive in nature, but may be related to the system. The most common system-related errors include:

  • Problems with policies and procedures

  • Inefficient processes

  • Teamwork

  • Communication

At more advanced levels of training, errors due to faulty or inadequate knowledge are uncommon.

Error reduction may be accomplished through both cognition and systems. Diagnostic errors are not exclusively cognitive in nature, and a culture that tries to develop perfection in cognition will fail to address errors adequately. Error-reduction interventions may include systems controls such as processes and procedures, engineering controls, and computer-based support.


Graber ML, Franklin N, Gordon R. Diagnostic error in internal medicine. Arch Intern Med. 2005 Jul 11;165(13):1493-9.

Newman-Toker DE, Pronovost PJ. Diagnostic errors--the next frontier for patient safety. JAMA. 2009 Mar 11;301(10):1060-2.

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