Using Differential Diagnosis to Confirm Your Illness

You've experienced symptoms of a medical problem, visited one or more healthcare providers, and have undergone medical tests. Now your healthcare provider will use all that evidence to arrive at your diagnosis, the conclusion as to what is wrong with you.

And sometimes, that system works. Other times, you'll find you have been misdiagnosed, or that the healthcare provider will fail to diagnose you at all. The frequency of missed or misdiagnoses is way too high, so it is that much more important that we patients understand how healthcare providers diagnose us, and what we can do to confirm they have arrived at the right answer.

Male patient and doctor in discussion in exam room
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The Process of Differential Diagnosis

How does your healthcare provider figure out your diagnosis? Their thought process should work like that of a detective. Using clues drawn from your descriptions of symptoms, your medical tests, their knowledge of medicine, and additional input, your healthcare provider will make a list of all the possible diagnoses that could explain what is medically wrong with you.

Then, one by one, using those same clues, they will begin to narrow down the list by finding clues that don't fit. That process of elimination is called "differential diagnosis." Ultimately they will be left with one diagnosis, and that's the one they give you.​​

What Happens Next?

Most patients think the next step is to ask about options for treatment. After all, they want to know how to fix or cure whatever their health problem is.

But you, the empowered patient, know better. Or at least you will, once you've learned what to do next.

Ask your healthcare provider, "What else can it be?" These five words can make a major difference in your care.

It's important for you to know what those other diagnosis options were, and why they were eliminated. You can get important insight into what's wrong with you by understanding them.

What You Can Learn

An important reason to understand what diagnoses were eliminated—and why—is to confirm that all the evidence was correct. For example, it's possible your healthcare provider misunderstood a symptom you experienced, or recorded your blood pressure incorrectly, or even mixed up your records with someone else's.

It's even possible you weren't entirely open with your healthcare provider, and that may have influenced their decision. For example, you may learn they rejected one diagnosis option based on the fact that you aren't running a fever. Perhaps they didn't realize, however, that you were taking aspirin to reduce the fever, and fever is one of your symptoms after all.

While your healthcare provider explains why they rejected each of the other options, listen carefully for additional clues. It could be that the clues used to discard a diagnosis are wrong. By reviewing the evidence with your healthcare provider, you'll be verifying that the correct evidence was used to determine your diagnosis. If it wasn't correct, then your healthcare provider may decide to reconsider.

Write down the names of the diagnoses your healthcare provider rejected. Later, if the treatment you choose doesn't seem to be working, you may wonder if you have been misdiagnosed. Misdiagnosis happens more often than we would like to believe, and knowing what your diagnosis' alternatives are can help you and your healthcare provider hone in on a more accurate answer later, if necessary.

What to Do Next

  • Once you understand your diagnosis, know why it was determined for you, and are relatively sure it's correct, you'll want to review treatment options with your healthcare provider.
  • You'll also want to spend time learning more about your diagnosis and treatment options so you can partner with your healthcare provider to make the best choice for your care.

Empowered patients understand the concept of differential diagnosis and use it to their advantage.