A misdiagnosis is, simply put, a wrong diagnosis. An erroneous diagnosis can take a number of forms, from a missed diagnosis in which no medical problem is identified when a problem exists, to a diagnosis which later turns out to be wrong, such as classifying a benign tumor as malignant. Misdiagnosis is a form of medical error, and while it is difficult to get accurate statistics on wrong diagnoses, some statistics place the rate at around one to two percent, with varying consequences.
There are a number of reasons for a misdiagnosis to occur. People who have suffered as a result of a misdiagnosis are often tempted to blame lazy doctors or medical personnel, but all kinds of things can be involved, including malfunctioning medical equipment, a patient's decision to conceal information, a language barrier between doctor and patient, inexperience on the part of the doctor, or a situation in which a diagnosis is extremely unusual, making it hard for a doctor to recognize the signs. Sometimes a disease may also manifest in an unusual way, with a doctor excluding a diagnosis because the symptoms do not fit and later realizing that the patient's case was atypical.
The consequences of a misdiagnosis are variable. If, for example, a patient's biopsied tumor is misdiagnosed as malignant when it isn't, he or she may undergo unnecessary medical procedures like surgery, chemotherapy, and radiation. On the other hand, if a doctor confuses two bacterial infections which can be treated with the same antibiotic, the outcome after misdiagnosis is the same, so it isn't as critically important.
Many hospitals and clinics work very hard to reduce misdiagnosis in their facilities. If a patient presents with an unusual manifestation of a disease, for example, other doctors may be invited to examine the patient and look at his or her records so that they can take note of things to look for in their own medical practice. When an error is made, medical staff work together to determine why the error happened, and how it can be prevented in the future. No-fault error reporting is also used to encourage doctors to disclose errors without fear of consequences so that they can be discussed and used as learning experiences for everyone.
For patients, there are some techniques which can be used to reduce misdiagnosis. The first is securing a second opinion, especially for major medical issues. Second opinions shouldn't be used to avoid making a decision about a medical problem like cancer, but they can be used to confirm a diagnosis. Securing a second opinion may also be a way to learn about additional treatment options. It is also important for patients to disclose everything, from the over the counter medications they take to the last time they had sexual contact. All of this information could be relevant, even if it doesn't seem to be on the surface.