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Articles » Medical Mistakes » Types of Medical Mistakes

Types of Medical Mistakes

There are many ways that your medical care can go wrong. All of the phases from diagnosis to treatment can have some type of error.

Studies of error types: An Institute of Medical report 1 attempts to quantify the types of medical errors that occur in healthcare settings. One cited study lists causes of error as follows:

  • technical errors (44%),
  • misdiagnosis (17%),
  • failure to prevent injury (12%),
  • medication errors (10%).

About 70% of all errors were believed to be preventable. The remainder were presumably non-preventable errors such as a patient reacting to a drug who had no previous history of an allergy to the drug.

National Patient Safety Foundation Survey: The National Patient Safety Foundation (NPSF) commissioned a phone survey in 1997 to review patient opinions about medical mistakes. The findings showed that 42% of people believed they had personally experienced a medical mistake. In these cases, the error affected them personally (33%), a relative (48%), or a friend (19%). Of these people, the type of mistake they had experienced was:

  • misdiagnosis (40%),
  • medication error (28%),
  • medical procedure error (22%),
  • administrative error (4%),
  • communication error (2%),
  • incorrect laboratory results (2%),
  • equipment malfunction (1%), and
  • other error (7%).

Unfortunately, the wording in the study for misdiagnosis was "misdiagnosis or wrong treatment", so it is unclear exactly how many were true misdiagnoses or wrong condition treated versus the wrong treatment for the correctly diagnosed condition. In other questions, people reported that they believed their doctor failed to make an adequate diagnosis in 9% of cases, and in another question 8% cited misdiagnosis as a causal factor in the medical mistake.

The location where the medical error was experienced was

  • hospital (48%),
  • doctor's office (22%),
  • operating room (7%),
  • clinic (5%),
  • emergency room (5%),
  • pharmacy (4%),
  • home (3%),
  • medical laboratory (1%),
  • nursing home (1%), and
  • other (5%).

When asked to cite what they believed primarily caused the error, NPSF survey respondents mentioned

  • carelessness/negligence (29%),
  • untrained staff/incompetence (14%),
  • communication (12%),
  • misdiagnosis (8%),
  • overworked staff (8%),
  • misread prescription or pharmacy error (6%), and
  • other (14%).

Diagnosis mistakes: there are various mistakes that can cause a misdiagnosis of a condition. Misdiagnosis can be one of the most costly of medical errors, leading to delayed, omitted, or inappropriate medical treatments.

  • Self-diagnosis mistakes: when you diagnose yourself, mistakes are very common. Always seek professional medical advice. Do not rely on internet health information.
  • Not diagnosed: some conditions are not obvious and may be missed, especially if they have no major symptoms.
  • Wrongly diagnosed: you might be diagnosed as having the wrong condition.
  • Wrong subtype of disease diagnosed: the diagnosis might have the correct overall disease, but the wrong subtype.
  • Complications not diagnosed: the diagnosed disease may have various complications that also need to be diagnosed and treated.
  • Underlying disease not diagnosed: there may actually be an underlying hidden disease causing the already diagnosed disease.
  • Associated diseases not diagnosed: some types of conditions cluster together, even though they do not cause each other.
  • Failure to diagnose others: infectious diseases need to be checked in family members and other exposed people; genetically associated diseases indicate family members may be at higher risk and may need screening.

Treatment mistakes: There are numerous ways that an error can occur in medical treatment.

  • Self-treatment mistakes: if you try to treat yourself, mistakes are very common. Always seek professional medical advice.
  • Wrong condition treated: i.e. from a misdiagnosis of the condition
  • Wrong choice of treatment plan: the overall strategy used to treat your condition might not be the best one.
  • Wrong type of treatment given
  • Wrongly delayed treatment: there might be an undesirable delay in your treatment, by choice or through non-diagnosis.
  • Wrongly performed procedures: all medical events such as surgeries and tests can have things go wrong.
  • Wrong medications: see below.

Prevention mistakes: The failure to prevent a condition is another type of medical failing. In certain cases, it is clear that preventive actions should be taken and failure to do so is a medical mistake.

  • Failure to prevent known complications of a diagnosed disease.
  • Failure to treat family members or others exposed to an infectious disease.
  • Failure to address clear risk factors for various conditions

Surgery mistakes: Surgical procedures are often complex and subject to various errors. Administration of surgery can also lead to errors. In some cases, there are known complications or risks of surgery than are often unavoidable.

  • Surgery administration mistakes: wrong-patient, wrong-site, wrong-organ, equipment left inside.
  • Surgical mistakes: the surgeon might make a wrong cut or other mistake.
  • Anaesthesia mistakes: too much, too little (waking up).
  • Complications from surgery
  • Infections from surgery: called "iatrogenic infections"
  • Wrong blood type transfusion

Hospital mistakes: A hospital can make errors in any of its varied activities. There are many staff who can make human mistakes and overall system problems can also lead to errors.

  • Hospital-caused infections: called "nosocomial infections"
  • Medication errors in hospitals: ordered medication not given, wrong medication, wrong dosage, wrong combinations, wrong patient given medication, and so on.
  • Wrong procedures: failure to do ordered tests, wrong procedures or tests.

Medication mistakes: Errors in medication are a major source of medical mistakes. Medication errors can occur in hospitals or pharmacies, and the error may be made by any of the staff involved with choosing or dispensing medication.

  • Inappropriate medication: the wrong medication given for a disease
  • Wrong medication: the patient gets the wrong medication despite the doctor prescribing the correct one.
  • Drug name mix-ups: several medications have similar-sounding names and can be mixed up by doctors or pharmacists.
  • Wrong medication combinations: there are numerous types of medications that should not be mixed, because of side effects and cross-reactions when combined.
  • Adverse reactions to medication: Some people have allergic or other adverse reactions to certain medications. These are risks and not necessarily avoidable mistakes if the person has no previous history of a particular adverse reaction.
  • Side effects of medication: Almost all medications have some types of side effects. Some are mild, some nasty. It is almost impossible to know up front whether a person will have side effects from a medication.
  • Non-compliance: the failure to follow your medication regimen can be a mistake made (usually by the patient).

Pharmacist errors: The dispensing of drugs by the pharmacy is a complex and busy activity. Various errors can occur at the pharmacist.

  • Wrongly filled prescriptions
  • Wrong drug supplied
  • Wrong dosage supplied
  • Drug name mix-ups: various drugs have similar names.

Pathology lab errors: Diagnostic testing done by a pathology laboratory can be subject to various errors. Some are administrative or human mistakes; other "mistakes" are inherent to the limitations of the type of test.

  • Wrong biopsy results: visual inspection of cellular slides
  • Administrative errors: mixing samples, etc.
  • Known test errors and risks: almost all tests have a small percentage of unavoidable errors (false positives, false negatives).
  • Known limitations of tests

Equipment failure errors: Physical failures with medical equipment can occur.

  • IV drips dislodged
  • Dead batteries in equipment

Unnecessary medical treatment: Excessive medical care can be a form of "mistake" for medical professionals and institutions. This can occur with good intentions (to ensure correctness) or for cynical reasons (to increase income).

  • Unnecessary procedures
  • Unnecessary tests
  • Unnecessary visits

1. Institute of Medicine (IOM), "To Err Is Human: Building a Safer Health System", 2000,online.

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