How to Analyze the Test Results and Choose a Working Diagnosis


Drs. Mendoza and Shah have asked you to interpret the results of the tests that were ordered for Brian Johnson choose a working diagnosis. The three tests ordered in Task 3 were a spinal X-ray, skull x-ray, and a head CT scan. Use the step-by-step instructions that follow to interpret the test results and choose a working diagnosis.

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 Brian Johnson - This file contains the results of the tests that Dr. Shah ordered for the patient (x-ray of spine, x-ray of skull, head CT scan)
     
     
2. Carefully review the email from Dr. Mendoza to become familiar with the goals of this task.
   
   
3. Briefly review Brian Johnson's test results.
• If you feel the test results are inconclusive, you have the option to order additional tests for this patient. Contact your mentor if this is your position, and be prepared to talk about what tests you would order and why.
  
  
4. Organize your team and create a plan for completing this work.
   

• 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.
  
• If you need a refresher on getting organized, refer back to the step-by-step in Task 1.
  
  
5. 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.
  
  
• Reread Step 4 of the Diagnosis and Treatment Process document: Test the diagnoses to confirm or disconfirm them. 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).

Revising the Differential Diagnosis

1. First, note any new findings that have a bearing on Brian Anderson ’s case.
   
   
   • Review the video and notes from the follow-up visit, and note any significant findings. Significant findings encompass anything abnormal, including:
     
     
     • The symptoms noted by Brian and his father
       
       
       • Were any symptoms mentioned during the follow-up visit?
       • Were any important details given related to the symptoms?
       • Were any of these symptoms lingering? Have they improved or worsened?
       • How have the symptoms responded to treatment? (Note: This is a particularly important question, since a failure to respond to treatment may indicate a problem with either the diagnosis or the treatment prescribed.)
       • Are there any new symptoms? If so, what are they?
         
         
     • Signs you observed in the physical examination
       
       
       • In what anatomical area(s) were abnormalities found, if any?
       • In what anatomical area(s) was pain localized? (You may write your answer in words; it may also help to sketch a picture indicating where significant pain and other symptoms were found.)
       • 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?
         
2. Integrate these new findings with the data that was gathered previously about Brian’s problem.
   
   
   • Review relevant items from Brian’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 Brian ’s risk factors for particular conditions and whether he is more likely to have some conditions rather than others. Also, if the patient has any prior health problems, it will help to ensure that you do not prescribe any treatment that is not indicated (in other words, unhealthy or unsafe) for a patient like him.

   • Review the patient’s story from the first (acute) visit. What mechanism of injury was suggested in the history?
     • If you can identify how the patient’s injury occurred and what abnormal motion or action 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.
       
   • Review the test results in the patient’s file. Were there any significant positive or negative results from early tests?
     • Do you find these results sufficiently convincing? If so, you can base a decision to include or omit a diagnosis on these test(s).
     • Do you have any reason to think that the test results may not have been completely valid or conclusive?
       • For example, some tests may not work well in revealing a particular diagnosis when the patient still has acute symptoms; they may need to be repeated later to get accurate results.
     • You may think that the tests were not sensitive enough in general to be conclusive in detecting a particular condition. In the next task, you’ll have the opportunity to order a more sophisticated test (or tests) if you feel they are warranted.

     Note: While you will need to cover all of the sub-steps that follow in Step 3 and Step 4, you can do so in any order that makes sense to you.

3. Organize your evidence in the Differential Diagnosis form.
   
   
   • Fill in the new evidence that you have for and against each diagnosis.
     
     
     • To do this, use the new information that you gathered in step one (above). Each piece of data gathered in the latest interview and examination may be able to serve as evidence for—or evidence against—a certain diagnosis. For each finding, ask:
       
       
       • Is this finding consistent with one or more of the diagnoses? If so, enter the finding as evidence for the diagnosis or diagnoses.
       • Is this finding inconsistent with, or would it contradict, one or more of the diagnoses? If so, enter the finding as evidence for the diagnosis or diagnoses.
       • In trying to make these matches, pay particular attention to the way the symptoms and signs have developed over time. Does this match the typical progression of symptoms and signs in a patient with a given diagnosis?
         
         
         • If you are not sure, you may need to do some research to find out more about the progression of symptoms that are typical for a diagnosis. What would you expect from a typical patient with the condition, if they are treated? If they go untreated?
           
           
       • You may also complete this substep in the opposite order, that is, look first at each diagnosis, and find the typical presentation of symptoms after 2 weeks with each condition. Then see if you have any findings for Brian that would support or contradict this picture.
         
4. Revise the ranking of the diagnoses in the differential.
   
   
   • Move all of the diagnoses that are no longer under consideration to the bottom of the list.
     
     
   • Rank all of the diagnoses that are still under consideration above the ones that are not. Order them from most likely to least likely, based on your evidence.
     
     
• 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 will have more pieces of evidence against it and fewer supporting it. However, you must have enough evidence (or enough “reasonable doubt” as they say in the law) in order to keep it on the list for further exploration.
  
  
• Make a careful decision about the diagnosis for the number one position; this will be your working diagnosis. Check your choice against the following questions:
  
  
• Is there a close match between the findings for this patient and a typical case of the condition?
• Were the test results consistent with the diagnosis? Do you think you might be able to obtain new, additional test results to support this diagnosis?
• Were there any findings that were not consistent with the diagnosis?
• Is this the most likely diagnosis for this patient, given the patient’s risk factors and the history of the present illness?
  
  
5. Check to make sure you have completed the entire form and that all of your work makes sense.
   
   
6. Review your work to make sure the information is complete, accurate, and coherent.
   

    

Meeting to Exchange Feedback

1. Meet with your cohort (made up of all teams participating in the rotation) to discuss your findings and ideas. You will be assigned one or more sections of the form at the beginning of the meeting; your team will present your key ideas and lead the discussion of that section with the cohort.
   
   • 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 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 more than one diagnosis may be correct because the patient may be suffering from multiple conditions with different signs and symptoms. However, physicians begin with the assumption that all of the patient’s symptoms are caused by the same condition and therefore look for evidence in favor of a single diagnosis.

Choosing a Working Diagnosis

• 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 differential 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 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 or facing more significant treatment 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.