Dr. Mendoza and Dr. Shah would like you to create the differential diagnosis for Brian Johnson. You will consider the results of the physical examination you recommended Dr. Shah perform on Brian, research the possible causes for his symptoms, and create a list of diagnoses that can explain all his signs and symptoms. You can include as many diagnoses as are reasonable; you should list them in order, from most likely to least likely.

Once you’ve finalized the differential, you should then determine what tests should be ordered, to test your differential. You should consider tests that can rule out a diagnosis as well as tests that could confirm a diagnosis.

Remember that, at this point, you are not determining a working diagnosis for the patient. You are creating a prioritized list of all of the possible diagnoses you will want to consider. Later, you will use this list to guide further testing of the patient and, ultimately, his treatment.

Getting Started

1. Prepare to do your work on this task.
   
   
   • Review Dr. Mendoza’s email and make sure you understand what you are being asked to do in this task.
   • Download and briefly review the following file attached to his email:
     • Differential Diagnosis Form (blank)—This is the template you will use to create the differential for Brian Johnson.
       
       
2. Organize your team and create a plan for completing this task.
   
   
   • In this task, you could create your own differential diagnosis proposal first, and then meet as a team to gather together everyone’s ideas. Of you could divide up the signs and symptoms and then share your research when you get together as a team. As you did in the first task, you should develop a rough timeline to plan when you will do your individual work and when you will get together to work as a team.
   • If you need additional help organizing your team, please refer to the Teamwork section of the General Skills Resources located in the left menu.

Preparing the Differential Diagnosis

1. Review your findings from Task 1, where you listed all the elements you wanted to test on the physical examination, and what each element would show you. Watch the video again, to be certain you have a list of all Brian’s signs and symptoms.
   
   
2. When you feel ready to learn how to develop a diagnosis, download and review the Develop a Diagnosis and Treatment Process document found in the Resources link (above).
   
   
   • This document is a reference that outlines the complete process of diagnosing and treating a patient.
   • You may not want to look at this until after you've seen the patient video once or twice and taken notes on your observations. Or you may want a sense of where you are going now. Read this document whenever you wish. You may refer back to it at various points in your work.
   • Pay special attention to Steps 1, 2 and 3. They are the steps you will work on in this task.

Develop the Differential Diagnosis

1. Review the clinical findings from the interview and examination of Brian Johnson. You should review Dr. Shah ’s case notes and any notes you took. You may also want to watch the Patient Interview video again. Be sure you note the following:
   • Any symptoms mentioned by Brian or his father
     • What symptoms did they mention during the interview?
     • When asked about his symptoms, what was the response?
   • Any abnormalities observed during the physical examination
     • In what anatomical area(s) where abnormalities found?
     • In what anatomical area(s) was pain localized? (As in previous tasks you may either write out an answer or sketch a picture indicating on the picture areas of significant pain.)
   • What normal functions or movements were affected? Describe how the patient’s functioning was different from normal functioning.
     • What structures control these movements in a normally functioning patient?
     • Why might the functioning of these structures be limited or changed in this patient?
     For help with any anatomy questions, please review the Science Links available in DATA in the Resources link (above).
     
     
2. Review relevant items from William’s general health history and patient profile, including:
   • health history
   • demographic information (age, gender, hometown, etc.)
   • lifestyle and habits

   This information will help you to determine William’s risk factors for particular conditions and whether he is more likely to have some conditions rather than others.

   For information on creating a differential diagnosis, feel free to refer to the Diagnosis and Treatment Process (section 4) and the references on Differential Diagnoses available in the Resources link (above).
   
   
3. Determine the mechanism of injury.
   
   
   • If you can identify how the patient’s injury occurred and what abnormal motion or action (if any) took place at the time of the injury, you can use this information to help develop and rank the differential.
   • Since certain motions, actions, or events will cause particular kinds of injuries, it will be helpful to compare the patient’s story with the typical one for each diagnosis.
     
     
4. Use DATA to research the possible diagnoses. In DATA, research each clinical finding you have gathered about Brian’s condition. Determine which diagnoses are linked to Brian’s signs and symptoms. You may choose to work from the research you began when planning the examination in the previous task (Task 4.1). If you choose this approach to this task, keep in mind that all the possible diagnoses that explain Brian’s symptoms may not have been included in your list. You should still review the clinical findings and make sure you are creating a differential complete with all the possible diagnoses. If you work from your previous notes, you should consider the following:
   
   
   • Do the clinical findings from the exam make any diagnoses you noted more or less likely?
   • Do any of the clinical findings specifically rule out a diagnosis you researched earlier?
     
     
5. Rank the diagnoses listed in your differential. Order the diagnoses from most likely to least likely, based on your evidence and their likelihood in general.
   
   
   • In order for a diagnosis to rank high on the list, it should have many pieces of evidence supporting it and few to none against it.
   • A lower-ranked diagnosis has fewer pieces of evidence supporting it and is less common. However, you must have enough evidence in order to keep it on the list for further exploration.
     
     
6. Complete the Differential Diagnosis Form.

   Remember: you have seen a Differential Diagnosis Form in other cases in this rotation, particularly the one that Dr. Chang completed for Jenny Anderson. You can look back at those forms, if you need help determining the type and amount of information you should include in each column.

   • In the first column, order the diagnoses from most likely to least likely, based on your evidence and their likelihood in general.
     • In order for a diagnosis to rank high on the list, it should have many pieces of evidence supporting it and few to none against it.
     • A lower-ranked diagnosis has fewer pieces of evidence supporting it and is less common. However, you must have enough evidence in order to keep it on the list for further exploration.
   • In the second column, include a list of the evidence supporting each diagnosis.
   • In the third column, list any evidence you have found so far that would be inconsistent with this diagnosis.
   • In the fourth column, indicate whether you are still considering this diagnosis. You may have found evidence in your research that allows you to rule something out without further testing, but it is likely that at this point you will be considering all the diagnoses listed in your differential.
   • In the fifth column, explain why you have included each diagnosis in your differential. Summarize the evidence for and against each diagnosis and a give general explanation of why you ranked the diagnosis where you did. You do not need to explain the row by row ranking (e.g. why you decided a diagnosis should be listed as number three instead of number four) but explain generally which diagnoses are more common.

7. Review the form to ensure that it is complete, accurate, and coherent.

Meeting to Exchange Feedback

1. Meet with your teammates to discuss your findings and ideas. Take some time for each person to share highlights of his/her work.
   
   
2. Come to a consensus on the proposed elements of the exam.
   
   
   • For this task, each team will submit one copy of the template. As a team, complete one Differential Diagnosis that incorporates everyone’s ideas.
     
     
3. Submit your work to your mentor. Be sure to save all your work, regardless of whether it is submitted to the mentor.
   

• Physicians do not build their hypotheses on very general signs and symptoms that are associated with numerous conditions. Instead, physicians use the more unique findings as the main foundation for identifying potential diagnoses. For example, temporary paralysis can indicate many conditions. While a physician would certainly take this symptom into account as indicating a problem, s/he would not use it as a foundation for creating a differential diagnosis. Instead, the physician would look for more specific signs and symptoms that would help to identify the specific condition.
  
  
• Physicians do try to figure out what processes are taking place in the body to cause the signs and symptoms. For example, the patient’s signs and symptoms may signify that there is an inflammatory process taking place in response to an injury or an immune response to a virus or bacterium. Physicians make some inferences about what the signs and symptoms suggest is going on in the body.
  
  
• Physicians do pay attention to the absence of certain symptoms or to negative findings in the physical examination or lab reports, when these will be helpful in making a diagnosis. For example, the ability to move a certain part of the body at least indicates that the nerve that controls that part of the body is not permanently damaged.
  
  
• Physicians do eliminate or lower the ranking of conditions that wouldn’t be responsible for some of the patient’s key symptoms. For example, nonallergenic rhinitis might be listed as a possible diagnosis causing a patient’s stuffy nose, but if the patient also has very itchy eyes, a symptom usually associated with allergies, then this diagnosis should either be lowered in rank or removed completely from the differential.
  
  
• Physicians do consider the likelihood of seeing a given condition in a patient of a certain age, gender, lifestyle, etc. They give more weight to conditions that are more likely to be seen in a certain population and move them higher on the list.
  
  
• In general, physicians do rank common conditions ahead of rare ones with similar symptoms. Many medical students learn the old saying, “When you hear hoofbeats, look for horses, not zebras.”
  
  
• Physicians do not always accept the information stated by a patient at face value. While the information gathered from a patient is often valuable, it can be imperfect; patients can forget or misremember the facts of their illness or injury. Sometimes patients can bias their reports (of pain severity or of their symptoms from a chronic or recurring condition) for personal reasons; for example, a competitive athlete may downplay a condition in order to continue participating in the sport, or a child might downplay the difficulty of a dangerous stunt that caused a fall so that his/her parents won’t get upset. Physicians should keep these possibilities in mind so they won’t rely on this information to be 100% accurate or complete as they create the differential.
  
  
• Physicians do need to understand the capabilities and limitations of various tests and lab information, especially in the early stages of a condition. Some tests are only helpful in diagnosis after a certain amount of time has passed. Certain injuries on X-rays may be hard to see, especially in particular views. Physicians need to be aware of all of this as they create the differential based on those particular pieces of information.
  
  
• Overall, physicians do approach the differential diagnosis by keeping an open mind and being as thorough and careful as possible.

Diagnosis and Treatment Archive - Sports Medicine

Diagnosis and Treatment Process
This document describes the process that health care professionals typically use to diagnose and treat their patients.

Orthopaedic Glossary
This glossary defines many of the terms used in this rotation.

These two links are supplements to the glossary:

Anatomical Terms of Location FAQ

Joint Motions FAQ

Ask the Expert

What is a differential diagnosis?

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