Medical Malpractice: Misdiagnosis and Delayed Diagnosis

A large number of medical malpractice lawsuits stem from the misdiagnosis or delayed diagnosis of a medical condition, illness, or injury. When a doctor's diagnosis error leads to incorrect treatment, delayed treatment, or no treatment at all, a patient's condition can be made much worse, and they may even die. That being said, a mistake in diagnosis by itself is not enough to sustain a medical malpractice lawsuit.

Read on to learn what a patient must prove in a medical malpractice lawsuit based on misdiagnosis, the different types of diagnostic errors, and why misdiagnosis is more common in emergency room settings. (To learn about other ways that medical malpractice can occur, see Nolo's article Medical Malpractice: Types of Doctor & Hospital Errors.)

Proving Medical Malpractice Based on Diagnostic Errors

The law does not hold doctors legally responsible for all diagnostic errors. Instead, patients usually must prove three things in order to prevail in a medical malpractice lawsuit based on a wrong diagnosis:

• A doctor-patient relationship existed.
• The doctor was negligent -- that is, did not provide treatment in a reasonably skillful and competent manner.
• The doctor's negligence caused actual injury to the patient.

Most medical malpractice cases hinge on either the second or third element (or both) -- was the doctor negligent and did that negligence harm the patient? (To learn more about the elements in a medical malpractice claim, see Nolo's article Medical Malpractice Basics.)

Was the Doctor Negligent?

A misdiagnosis or delayed diagnosis itself is not evidence of negligence. Skillful doctors can and do make diagnostic errors even when using reasonable care. The key is determining whether the doctor acted competently, which involves an evaluation of what the doctor did and did not do in arriving at a diagnosis. This means looking at the "differential diagnosis" method the doctor used in making treatment determinations.

Differential diagnosis is a systemic method used by doctors to identify a disease or condition in a patient. Based upon a preliminary evaluation of the patient, the doctor makes a list of diagnoses in order of probability. The physician then tests the strength of each diagnosis by making further medical observations of the patient, asking detailed questions about symptoms and medical history, ordering tests, or referring the patient to specialists. Ideally, a number of potential diagnoses will be ruled out as the investigation progresses, and only one diagnosis will remain at the end. Of course, given the uncertain nature of medicine, this is not always the case.

Sometimes, after further investigation, the doctor will discover other information that will cause him or her to add to the differential diagnostic list.

In a medical malpractice case based on diagnostic error, the patient must prove that a doctor in a similar specialty, under similar circumstances, would not have misdiagnosed the patient's illness or condition. In a practical sense, this means proving one of two things:

• The doctor did not include the correct diagnosis on the differential diagnosis list, and a reasonably skillful and competent doctor under similar circumstances would have.
• The doctor included the correct diagnosis on the differential diagnosis list, but failed to perform appropriate tests or seek opinions from specialists in order to investigate the viability of the diagnosis.

Errors in Diagnostic Tests

Sometimes a doctor fails to correctly diagnosis a condition because they relied on inaccurate results from laboratory tests, radiology films, or other types of tests. This can happen in one of two ways:

• The diagnostic equipment was faulty.
• Human error occurred -- for example, the samples were contaminated or mixed up, the technician used an improper procedure, the test results were read incorrectly, or the technician or specialist missed something in an x-ray or pathology slide.

Although the doctor might not be liable for medical malpractice in this situation, another person might be -- such as the technician that misread the pathology slide. Again, the patient must prove that the error was the result of negligence.

Did the Misdiagnosis Harm the Patient?

The patient must also prove that the doctor's negligent misdiagnosis or delayed diagnosis caused the patient's injury or condition to progress beyond where it normally would have -- had the correct diagnose been made in a timely manner -- and that this progression had a negative impact upon treatment. For example, because of a delayed cancer diagnosis the patient had to undergo a more severe treatment regimen (such as chemotherapy) or the patient died because the cancer had metastasized and no longer responded to treatment. Sometimes a patient can show harm even if the condition can still be treated. For example, with some cancers a delay in treatment increases the risk of recurrence.

In the rare case that a doctor diagnoses a patient with a condition or illness that the patient does not have, the patient may also be able to prove harm in the form of anxiety, stress, medical problems, and expenses due to unnecessary treatment.

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