Diagnostic Reasoning

Clinical decision making is the process by which we determine who needs what and when. While not exactly arbitrary, this exercise can be quite subjective. Each provider compiles their own data (hence the emphasis on learning to perform an accurate H&P) and then constructs an argument for a particular disease state based on their interpretation of the "facts." The strength of their case will depend on the way in which they gather and assemble information. There may then be no single, right way of applying diagnostic and therapeutic strategies to a particular case. Medicine involves playing the odds, assessing the relative chance that a patient is/is not suffering from a particular illness. Codifying the way in which providers logically approach problems and deal with this uncertainty is a difficult task. Relying solely on the classic features of a disease may be misleading. That is because the clinical presentation of a disease often varies: the symptoms and signs of many conditions are non-specific initially and may require hours, days, or even months to develop. Generating a differential diagnosis; that is, developing a list of the possible conditions that might produce a patient's symptoms and signs, is an important part of clinical reasoning. It enables appropriate testing to rule out possibilities and confirm a final diagnosis. This case portrays a poor patient outcome after a misdiagnosis. Case scenario A previously healthy 35-year-old lawyer presents to a primary care office with a chief complaint of chest pain and a non-productive cough. The pain started suddenly two hours prior to coming to the office while the patient was sitting at his desk. The patient describes the pain as sharp in nature, constantly present but made worse with inspiration and movement, and with radiation to the base of the neck. His blood pressure in the right arm and other vital signs are normal On physical examination, the only findings of note are chest wall tenderness and a faint cardiac murmur. The ECG in the office is normal. The patient is observed for an hour in the office and assessed. He is diagnosed with viral pleurisy and sent home on non-steroidal analgesics. The following day the patient collapses at home and cannot be resuscitated by the paramedic service. An autopsy reveals a Type 1 aortic dissection with pericardial tamponade. Developing a list of possible conditions that might produce a patient's symptoms and signs is an important part of clinical reasoning. As an NP in primary care, what would you have done differently? Discuss the importance of creating a list of differentials for this patient. How could it have changed this outcome? If a serious diagnosis comes to mind based on a patient's symptoms: Ask yourself: Have you considered the likelihood of a serious diagnosis and whether it needs to be ruled out by testing or referral? Because many serious disorders are challenging to diagnose, have you considered ruling out the worst-case scenario? Ask yourself: Do you have a sufficient understanding of the clinical presentation to offer an opinion on the diagnosis? What other diagnoses could it be? How might the treatment to date have altered the patient's outcome? What other diagnostic and laboratory or imaging was needed in order to make a complete differential list? What support tools would you consider using in helping to create a differential diagnosis list? Are you familiar with the current clinical practice guidelines for the investigation of a suspected condition such as chest pain?

Sample Solution

As an NP in primary care, what would I have done differently?

Based on the case scenario provided, I would have done the following differently:

Given the patient's sudden onset of sharp chest pain, radiation to the neck, and faint cardiac murmur, I would have considered the possibility of a more serious condition such as an aortic dissection. While viral pleurisy is a common cause of chest pain, it is important to consider other possibilities, especially in patients with atypical presentations.
I would have ordered an ECG and a chest X-ray to rule out other potential causes of chest pain, such as a myocardial infarction, pulmonary embolism, or pneumothorax. These tests are relatively non-invasive and can be helpful in narrowing down the differential diagnosis.

Full Answer Section

I would have admitted the patient to the hospital for further evaluation and monitoring. Given the patient's sudden onset of chest pain and atypical presentation, I would have been concerned about the possibility of a serious condition that could require emergent intervention.

The importance of creating a list of differentials for this patient

Creating a list of differentials is an important part of clinical reasoning. It allows clinicians to consider all of the possible causes of a patient's symptoms and signs. This is especially important in patients with atypical presentations or multiple comorbidities.

In the case scenario provided, creating a list of differentials could have changed the outcome by leading to earlier diagnosis and treatment of the patient's aortic dissection. If the clinician had considered the possibility of an aortic dissection, they could have ordered the appropriate tests and admitted the patient to the hospital for further evaluation and monitoring. This could have potentially saved the patient's life.

Asking yourself if you have considered the likelihood of a serious diagnosis and whether it needs to be ruled out by testing or referral

When a patient presents with symptoms that could be due to a serious condition, it is important to consider the likelihood of that diagnosis and whether it needs to be ruled out by testing or referral. In the case scenario provided, the patient's sudden onset of sharp chest pain and radiation to the neck were concerning for a serious condition such as an aortic dissection. The clinician should have considered the likelihood of this diagnosis and ordered the appropriate tests to rule it out.

Ruling out the worst-case scenario

Because many serious disorders are challenging to diagnose, it is important to consider ruling out the worst-case scenario. This can be done by ordering the appropriate tests and admitting the patient to the hospital for further evaluation and monitoring.

Assessing whether you have a sufficient understanding of the clinical presentation to offer an opinion on the diagnosis

Before offering an opinion on the diagnosis, it is important to assess whether you have a sufficient understanding of the clinical presentation. In the case scenario provided, the clinician may not have had a sufficient understanding of the clinical presentation of an aortic dissection to accurately diagnose the patient. If the clinician had been unsure about the diagnosis, they should have referred the patient to a specialist for further evaluation.

Considering other possible diagnoses

In addition to aortic dissection, other possible diagnoses in the case scenario provided include myocardial infarction, pulmonary embolism, pneumothorax, and pericarditis. The clinician should have considered all of these possibilities and ordered the appropriate tests to rule them out.

How the treatment to date may have altered the patient's outcome

If the clinician had diagnosed the patient's aortic dissection earlier, the patient could have been treated with surgery or endovascular repair. This could have potentially saved the patient's life.

Other diagnostic and laboratory or imaging tests needed to make a complete differential list

In addition to the ECG and chest X-ray, other diagnostic and laboratory or imaging tests that could have been helpful in making a complete differential list include:

Blood tests: troponin, creatine kinase-MB, D-dimer, complete blood count, and basic metabolic panel
Imaging tests: transesophageal echocardiography (TEE), computed tomography angiography (CTA), and magnetic resonance imaging (MRI)

Support tools for creating a differential diagnosis list

There are a number of support tools available to help clinicians create a differential diagnosis list. These tools include:

Clinical decision support systems (CDSS): CDSS are computer-based programs that can help clinicians identify and rule out potential diagnoses.
Differential diagnosis databases: Differential diagnosis databases provide clinicians with a list of possible diagnoses based on the patient's symptoms and signs.
Clinical practice guidelines: Clinical practice guidelines provide clinicians with evidence-based recommendations for the diagnosis and treatment of various

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