How to Develop a Differential Diagnosis

Dr. Mendoza and Dr. Shah would like you to create the differential diagnosis for William Rand. You will consider the results of the physical examination you recommended Dr. Shah perform on William, research the possible causes for his symptoms, and create a list of options 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 work on this task.
   • Download and review the email attachments.
     • WRand Interview and Physical Examination Form—This form now contains Dr. Shah’s notes from both the interview and physical examination.
     • Differential Diagnosis Form (Blank)—This is the template you will use to organize your differential diagnosis.
       
       
2. Organize your team and create a plan for completing this task.
   
   
   1. In this task, you will work first to create your own differential diagnosis and then meet as a team to compile everyone’s ideas. Again, to help complete the task efficiently, you should develop a rough timeline to plan when you will do your individual work and when you will come together to synthesize this work for the team deliverable.
   2. Plan a time to meet with your team for your first work session.
   3. If you need help organizing your team on this task, review the information on Teaming in the General Skills Resources in the left menu.
      
      
3. Together with your team, review the email from Dr. Mendoza and make sure you understand what you are being asked to do.

Create the Differential Diagnosis

1. Review the clinical findings from the interview and examination of William Rand. 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 William 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 understanding the anatomy of the hip, 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 William’s condition. Determine which diagnoses are linked to William’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 William’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 differential diagnosis.
   
   
   • As a team, create a differential diagnosis that you can agree upon, to submit as a group deliverable.
   • Complete one Differential Diagnosis Form that represents the work of your entire team.
   • To help you, see the resources on Teamwork, especially the articles on collaborative group work and collaborative writing, in the General Skills Resources in the left menu.
     
     
3. Submit your work to your mentor. Be sure to save your work whether or not you will submit it to the mentor.

There are no new Tips/Traps for this task. For guidance on creating a differential diagnosis, refer back to Tips and Traps for Case 2:Skateboarding Slip-up, Task 1.2 (Differential Diagnosis).

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?

What is avascular necrosis?