3 things you need to make a Misdiagnosis Claim

A misdiagnosis or delayed diagnosis of a medical condition, illness or injury may result in a medical malpractice lawsuit. In fact, a significant number of malpractice lawsuits are due to misdiagnosis claims. 

When a doctor’s misdiagnosis results in incorrect treatment, delayed treatment or no treatment at all, the patient’s condition may worsen and they may even die. However, not all diagnostic errors constitute a medical malpractice lawsuit.

Proving Medical Malpractice Based on Possible Misdiagnosis

Doctors are not held legally accountable for every error in diagnosis. Usually, patients must prove three things in order to make a misdiagnosis claim. These three things are

As mentioned before, not all misdiagnosis or delayed diagnosis are sufficient to make a misdiagnosis claim. 

Even skillful and competent doctors can make mistakes. 

To prove the second point from the list above, the patient must demonstrate that another doctor of a similar specialty, under similar circumstances would have been able to make the correct diagnosis. This involves evaluating the primary doctor’s differential diagnosis, which is a method used to narrow down a list of possible medical conditions to arrive at a final diagnosis. 

After an initial medical examination, the doctor will list the possible diagnoses in order of probability. To investigate the strength of each diagnosis, the physician will order tests, ask about your symptoms and medical history and refer the patient to specialists until, ideally, only one diagnosis remains.

In a medical malpractice lawsuit, the patient must prove that the doctor had failed to include the correct diagnosis in their differential diagnostic list, but a skilled and competent doctor would have included it. If the correct diagnosis was on the list, the patient must show that the doctor failed to order the appropriate tests or did not refer to specialists for their opinions in the diagnosis of their condition.


Misdiagnosis may also result from the use of inaccurate results from laboratory tests, radiology films, or other types of tests. This can happen due to defective diagnostic equipment or human error. Human error in diagnosis encompasses a wide variety of events such as the contamination or mix up of samples, incorrect reading of test results, or the technician using the wrong procedure. 

In the last scenario, it may be the technician that was responsible for the misdiagnosis. Similarly, the patient must prove that negligence caused the error. 

Did the Misdiagnosis Harm the Patient?

If the misdiagnosis or delayed diagnosis caused the patient’s condition to worsen beyond what it would have if it had been properly diagnosed in a reasonable amount of time, then the misdiagnosis has harmed the patient. 

This may come in the form of the patient undergoing a more severe treatment regimen because of a delayed diagnosis, or even no response to treatment since the disease had already progressed to an advanced stage.

In certain diseases where a delayed diagnosis increases the risk of recurrence, a patient can also show harm in this manner. If the doctor diagnosed the patient with a disease they did not actually have, then the patient may experience anxiety, stress or medical complications, which can also be labelled as harmful to the patient. The expenses incurred due to unnecessary treatment can also be considered harmful.

Types of Diagnostic Mistakes

Wrong diagnosis

Wrong diagnosis

A wrong diagnosis, also called a misdiagnosis, is when the doctor diagnoses the patient with the wrong condition. For example, the doctor diagnoses the patient with anxiety when the patient actually has a heart disease.

Missed diagnosis

Missed diagnosis

A missed diagnosis is when the doctor diagnoses the patient as completely healthy, when in fact, the patient does have a disease.

Missed diagnosis

Delayed diagnosis

A delayed diagnosis is when the doctor diagnoses the patient correctly but after a long duration of time. This is one of the more common types of diagnostic mistakes.

Failure to recognize complications

Failure to recognize complications

The doctor correctly diagnoses the patient but does not recognize the complications which cause the condition to worsen.

Failure to diagnose a related disease

Failure to diagnose a related disease

The doctor correctly diagnoses the patient, but does not diagnose a related disease. A related disease may be one that is often associated with the primary condition or one that the patient is predisposed to due to having the primary condition.

Failure to diagnose an unrelated disease

Failure to diagnose an unrelated disease

The doctor correctly diagnoses the patient but does not diagnose an unrelated second disease.

Due to the nature of the illnesses and injuries in the emergency room, mistakes in diagnosis are more common. 

Doctors often have to make a quick diagnosis and triage patients in the ER, which may compromise their ability to make a thoughtful differential diagnosis. The increased severity of the injuries and illnesses presented in the ER will thus be more harmful to the patients if an incorrect diagnosis is made. 


In an emergency room, less common conditions are more likely to be misdiagnosed. This can occur when the condition is uncommon in a certain patient population or presents differently in that population. 

For example, a young woman presenting with gastric distress (one symptom of a heart attack) is less likely to be diagnosed with a heart attack than an overweight, middle-aged man presenting with the same symptoms. 

Conditions that are commonly misdiagnosed in an emergency room include heart attack, stroke, pulmonary embolism and meningitis. An example of a disease that is misdiagnosed due to it being rare in a certain population is appendicitis. In children under the age of 12, appendicitis is misdiagnosed 28% to 57% of the time. In infants, it is misdiagnosed close to 100% of the time. 


Article from Nolo. Original article written by Kathleen Michon

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