Clinical Reasoning: Storing Stories to Narrow the Diagnosis

Medical interns with patient.

By Martina McGrath, MD
October 24, 2017

Accurate clinical reasoning is central to the art of medicine, and involves complex cognitive processes that most clinicians perform unconsciously. However, teaching these skills is an essential component of developing expert clinicians. In an era of rising healthcare costs, increased access to diagnostic testing and unlimited access to knowledge, the ability to sift through large amounts of data, synthesize a clinical presentation in a meaningful way and develop a logical differential diagnosis with a focused, rational plan of evaluation, is perhaps more important than ever.1

Skilled clinical reasoning follows a series of steps, beginning (as we were all taught in medical school) with history-taking and physical examination. As the clinician talks to the patient, she begins to develop an impression of the patient’s story, known as a mental abstraction.2 This mental abstraction guides further questioning and clinical examination. After acquiring the relevant data, the clinician must develop a concise one-line summary of the findings, a ‘problem representation,’ incorporating the most important features of the case, relevant negatives, and a differential diagnosis. The problem representation is an essential step in synthesizing the data to formulate a plan of diagnosis and treatment.

A specific patient presentation can trigger recall of a memory of a previous clinical encounter, along with its associated knowledge, which may include pathophysiology, treatment, complications, etc.

Helping trainees (particularly those early in their careers) to develop accurate problem representation allows them to accurately access their stored knowledge about a particular medical problem. If the presentation is not framed appropriately, the correct information cannot be accessed, leading to increased likelihood of unfocused reasoning and diagnostic errors. Teachers should encourage learners to develop a one-line summary and then explore that summary, using open questions such as “Why do you think that?” or “What features support/do not support that conclusion?” This approach informs the teaching physician of the trainees’ thinking process, and also encourages greater engagement by the trainee in clinical reasoning. It can be very instructive if the teacher then gives their own summary and reasons aloud, illustrating how the case links to their prior experience, and demonstrating effective clinical reasoning strategies.

Experienced clinicians mentally develop personal ‘illness scripts’, a repertoire of patient stories that connect prior clinical experiences with medical knowledge, and store them as accessible memories that guide diagnostic reasoning.2,3 A specific patient presentation can trigger recall of a memory of a previous clinical encounter, along with its associated knowledge, which may include pathophysiology, treatment, complications, etc. Possession of a broad range of illness scripts allows expert clinicians to rapidly formulate a diagnosis, but also recognize atypical presentations and break down complex cases into their component parts.

Encouraging the development of a trainee’s personal repertoire of illness scripts is central to clinical training. Repeated patient interactions, particularly early in a hospitalization before all testing is complete, are critical to developing this skill.4  Each experience feeds into the knowledge base behind illness scripts. Guided discussion with an experienced clinician helps to consolidate these mental connections, and provides very valuable insights. Also when rounding on admitted patients, critical reflection helps to consolidate illness scripts, and avoids cognitive errors due to failure to challenge that initial diagnostic label as more information becomes available later.

Those of us who have been fortunate enough to train with outstanding clinicians will recognize these approaches. Solving the puzzle and getting to the right treatment plan is one of the more rewarding aspects of being a medical professional, and should be a cherished skill to hand on to our future colleagues.

Learn to develop essential skills in clinical research.


  1. Cooke S, Lemay JF. Transforming Medical Assessment: Integrating Uncertainty Into the Evaluation of Clinical Reasoning in Medical Education. Acad Med. 2017 Jun;92(6):746-751. doi: 10.1097/ACM.0000000000001559.
  2. Bowen JL. Educational strategies to promote clinical diagnostic reasoning. N Engl J Med. 2006 Nov 23;355(21):2217-25.
  3. Elstein AS, Schwartz A. Clinical problem solving and diagnostic decision making: selective review of the cognitive literature. BMJ 2002;324:729-32.
  4. Simpkin AL, Vyas JM, Armstrong KA. Diagnostic Reasoning: An Endangered Competency in Internal Medicine Training. Ann Intern Med 2017;167:507-8.

Head shot of Dr. Martina McGrathDr. Martina McGrath is an Instructor in Medicine at Harvard Medical School, and a member of the Renal Division, Department of Medicine, at Brigham and Women’s Hospital, both in Boston. Dr. McGrath is the former Medical Editor for the Trends in Medicine blog.




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