How to Analyze the Test Results and Choose a Working Diagnosis


Now that you have the test results in hand, it is time for you to critique Dr. Chang 's work in analyzing the results, drawing conclusions, and incorporating this information into her differential diagnosis. It is your job to evaluate whether Dr. Chang interpreted the tests results correctly, revised her differential appropriately, and chose the correct working diagnosis.

Use the step-by-step instructions that follow to critique Dr. Chang's analysis and diagnosis and to evaluate the reasoning behind her choices.

Getting Started

1. Get prepared to do your work in this task. Go to the email sent to you by Dr. Mendoza, and download the attachments. You will need the following throughout the task:
   
   
   • Test Results for Jenny Anderson - This file contains the results of the tests that Dr. Chang ordered for the patient.
     
     
   • Differential Diagnosis (Revised) - This form shows how Dr. Chang decided to revise her differential diagnosis after receiving the test results for the patient and provides her current working diagnosis.
     
     
   • Critique Template of the Revised Differential Diagnosis - This is the form that physicians at Lakeshore Hospital use to critique a fellow physician's conclusions from test results and revision of the differential diagnosis.
     
     
2. Carefully review the email from Dr. Mendoza to become familiar with the goals of this task.
   
   
3. Briefly review the attachments to the email – the Differential Diagnosis (Revised) and the Critique Template of the Revised Differential Diagnosis– to become more familiar with the contents of each. Also, briefly review Jenny Anderson's x-rays.
   
   
   • Work with your teammates to create a quick list of the questions that you have about how physicians read and interpret test results and revise their differential diagnoses. As before, these questions may help you in formulating your thoughts as you begin this task.
     
     
   • Briefly, the key pieces to looking at an x-ray are to compare what is normal to what you have in front of you, both in terms of the shapes of the bones and the spaces between them. Specifically:
     1. Examine each bone for any evidence of fracture or deformity. Have your anatomical resources available to compare with Jenny's x-ray so that you have a baseline understanding of how the bones should look.
     2. Examine the spaces between the bones for any abnormal shift, strain or rupture.

     To view some normal x-rays to compare with Jenny's, and also to learn more about how to read an x-ray, see the Resources (above).

4. Read about the methods physicians use to evaluate test results and refine the differential diagnosis.
   
   
   • As you read, take notes on any material you find that answers the questions you raised with your team or that may help you to critique Dr. Chang's choices.
     
     
   • Reread section 4 of the Diagnosis and Treatment Process document: Test the first diagnosis to confirm or disconfirm it. This section explains how a physician revises the differential diagnosis as test results arrive.
     
     
   • For additional guidelines that physicians follow during this step of the diagnosis and treatment process, see the Tips and Traps (above).
     
     
5. Organize your team to do the critique.
   
   
   • If you need a refresher on getting organized, refer back to the step-by-step in Task 1.

Completing the Critique Template

To help you determine whether you agree with the physician's revision of the differential diagnosis, follow the steps below.

1. Examine Dr. Chang's revised differential and note each change that she made. (Changes are summarized at the top of the document and also bolded within the table.)
   
   
2. Return to the x-rays taken of Jenny Anderson's foot and ankle (attached to the email from Dr. Mendoza), and decide whether you believe Dr. Chang read the x-rays correctly.
   
   
   • Do you agree with Dr. Chang's interpretation of the x-rays? To help you decide, compare Jenny's x-rays with examples of x-rays showing each diagnosis in other patients.
     
     
3. Decide whether you agree with Dr. Chang's interpretation of the test results for the diagnoses tested.
   
   
   1. Examine each diagnosis that Dr. Chang ruled out based on the test results (or, revised so that it is no longer under consideration). Do you agree with her conclusion to definitively rule out this diagnosis, or do you think there is still a chance that it could be viable?
      
      
   2. You might need to research a bit more information about the test(s) used. Remember, one test may be more accurate in detecting some diagnoses than others. For each test used to uncover information about a diagnosis, you should find out:
      
      
      • Does a negative result on this test usually rule out this diagnosis with near-certainty?
        
        
      • Can abnormal results sometimes be difficult to see? Does this test require time to pass before it will show an abnormal result?
        
        
   3. Evaluate Dr. Chang's decisions in revising the differential.
      
      
   4. Note where you would have made different decisions. What would you have written instead? What evidence supports your conclusions? In explaining your reasons, discuss any factors you think Dr. Chang should have given more or less weight.
      
      
4. Next, decide whether you agree with Dr. Chang's current ranking of those diagnoses which were not investigated further through testing. For each diagnosis, you should answer the question, In your opinion, is this diagnosis ranked properly in the differential at this time? To prompt your thinking, ask yourself:
   
   
   • Does the current evidence for (or against) this diagnosis justify its ranking in the differential?
     
     
   • Has any information been uncovered through further investigation that might suggest its ranking, in terms of likelihood, should be changed? What, if any, additional evidence should have been added?
     
     
   • Or, is a definitive ranking impossible for the physician to make until additional information is available (e.g., until he can observe the patient's progress with the passage of time)?
     
     
5. Check to make sure you have completed the entire table.
   

Meeting to Exchange Feedback

1. Meet with your cohort (made up of all teams participating in the rotation) to discuss your findings and ideas. Your mentor will assign your team one or more sections of the critique form at the beginning of the meeting. Your team will present your key ideas and lead the discussion of that section.
   
   
   • For tips on meeting to exchange feedback, see the Tips and Traps (above).
     
     
   • Jot down notes to record what you gain from the discussion. Write any answers you found to the questions you and your teammates posed in the beginning of this task. You may also note down any questions you still have about analyzing tests and making a diagnosis.
     
     
2. After incorporating any feedback you may have received during the discussion, submit your work to your mentor. Be sure to save all of your work, regardless of whether you submit it to the mentor.
   

Analyzing the Test Results

• Physicians do consider the probability (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 higher than rare ones with similar symptoms. There is a saying common in medical school: “When you hear hoofbeats, look for horses, not zebras.” However, they are also aware of what is common in their particular practice environment, adding, “When you hear hoofbeats, look for horses, not zebras, unless you are at the zoo.”
  
  
• Physicians do sometimes use the passage of time as an additional diagnostic test when the diagnosis is still unclear. It may take several observations separated by time for the pattern of the disease or condition to become clearly recognizable. This also gives the physician an opportunity to see what effect, if any, the initial treatment has had on the patient. This can provide valuable information about whether the initial diagnosis was correct. In some cases, the symptoms may simply fade away. Physicians limit their use of this approach to cases where it should not harm the patient to let some time pass.
  
  
• Physicians do recognize that even with apparently normal x-rays, the patient may still have sustained certain fractures. Some fractures only appear in an x-ray a few weeks after the injury occurs. Some fractures may be hard to see in an x-ray if the foot or ankle was not positioned “just right” to get a proper view of the injured part of the bone. Physicians should be cognizant of the conditions for which this situation could occur and should not rule them out prematurely.

Choosing a Working Diagnosis

• Physicians do take the highest-ranking item on the differential (the most likely diagnosis) and use it as their working diagnosis. Physicians do not change this working diagnosis unless they get convincing evidence that the patient does not have the condition or that s/he has a different condition. However, they do maintain awareness that their initial diagnosis could be wrong and keep other possibilities in mind in order to ensure proper care of the patient.
  
  
• In order to protect the health and safety of the patient, physicians do consider the potential consequence of making an incorrect diagnosis. They consider whether the patient could risk having any permanent physical damage by failing to treat an alternative condition. If the patient most likely would not be harmed in any way, the physician can feel comfortable going forward with treatment for the top-ranked diagnosis, knowing that he/she can change course later in light of additional evidence.
  
  
• Even in this age of high technology, there will likely be elements of uncertainty in a case. Overall, physicians do approach the diagnosis by being as thorough and careful as possible, while also choosing a working definition of the problem that will allow the patient and the doctor to move ahead.

Meeting to Exchange Feedback

• Do back up the points you make with your research and with strong, logical arguments.
  
  
• Do remain open to hearing disagreement or different ideas from other teams. If your points generate some debate, then you know you have done your job well and hit upon an interesting issue. Both your team and other teams can learn from the discussion.
  
  
• Do listen carefully to the thoughts the other teams are sharing, and note how they are the same or different from your own. Remember that there is not necessarily a “right” answer that all physicians would agree with. Different physicians use different approaches.

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

How to Read an X-Ray FAQ
This document describes how x-rays work, and breaks down how to read an x-ray.

To view normal ankle x-rays for comparison:

Normal Ankle X-Ray

Normal Ankle Stress X-Ray