Defining 11 common types of medical errors, patient harms

1. Medication errors

Medication errors are among the most common forms of adverse patient safety events. These types of patient safety incidents happen in around 6.5% of acute hospital stays, according to a 2024 StatPearls report.

Medication errors can occur in several ways, including prescribing the wrong medication or the wrong dose. Additionally, a medication error might occur when a medication is administered in an unintended way, such as orally instead of intravenously.

Finally, a medication error might occur when the medication is simply never administered or it is administered at the wrong time.

2. Surgical errors

Surgical errors are mistakes that happen before, during or after a surgical procedure. This includes wrong-site surgery, wrong-patient surgery, surgeries during which surgical instruments were unintentionally left inside the patient and postoperative complications. Postoperative complications can include infections and excessive bleeding.

According to a National Institutes of Health (NIH) report outlining numerous types of medical errors, surgical errors are serious because they are the biggest drivers of severe patient injury and death. NIH says that intraoperative errors, in particular, are the primary issue in 75% of medical malpractice cases involving surgeons.

Key measures to prevent surgical errors are mostly process-related, as the causes behind many surgical errors are often linked to clinician factors, medical record issues and cognitive errors. Practices such as making checklists, counting instruments and using specialized instruments like radio-frequency sponges can move the needle on surgical errors.

Moreover, human-centered interventions can help prevent surgical errors. For example, surgical time-outs, a practice during which the entire surgical team takes a pause before initiating a procedure, can help flag potential errors and make a potential adverse event a near-miss, NIH advised.

3. Healthcare-associated infections

Healthcare-associated infections, or hospital-acquired infections (HAIs), represent a key example of a health system or process failure, according to the NIH medical errors resource. HAIs happen in as many as 1 in 20 hospitalized patients, the consequences of which include longer hospital stays and higher costs.

Common HAIs include catheter-associated urinary tract infections, central line-associated bloodstream infections, surgical site infections and ventilator-associated pneumonia.

Strategies to prevent HAIs are largely human-centered, considering the role health system processes play in this aspect of patient safety. Improving hygienic practices has been shown to move the needle on HAI rates.

4. Diagnostic errors

The National Academies of Science, Engineering, and Medicine define a diagnostic error as "the failure to establish an accurate and timely explanation of a patient's health problems or to communicate that explanation to the patient." Diagnostic errors can include delayed, wrong or missed diagnoses.

Diagnostic errors comprise the largest portion of medical malpractice claims, according to the Society to Improve Diagnosis in Medicine. They also cause the most severe patient harm, the Society added, and accumulate the highest total of penalty payouts.

Like most medical errors, diagnostic errors are often the result of process errors, and they can be prevented. The Joint Commission recommends 10 best practices for preventing diagnostic errors, ranging from standardized review systems, closed-loop communication, patient review of health records, multidisciplinary care teams and an organization-wide culture of safety that incentivizes honest communication about and reporting of potential errors.

5. Falls

Falls are a common type of patient safety incident among older patients over age 65. According to Agency for Healthcare Research and Quality data, falls happen in three to five per 1,000 bed-days, and they result in between 700,000 and a million hospitalizations each year.

Patient falls have many causes, including the following:

• Blood loss.
• Medication side effects.
• Postanesthesia effects.
• Decreased blood sugar.
• Altered mental status.
• Decreased strength or balance.
• Advanced age.
• Mobility impairment.
• Inadequate staffing.
• Increased proportion of new nursing staff.

Healthcare organizations have begun to implement protocols to prevent falls. Fall risk assessments, staff education, patient mobility training and nutritionist support have worked to address the root causes of in-hospital falls. Patient safety rounding, bed alarms and caregiver education have also been fruitful, according to the NIH resource.

6. Pressure injuries

Pressure injuries, or pressure ulcers, happen to between 1 and 3 million people in the U.S. each year, according to another StatPearls report specific to pressure injuries. These types of adverse patient safety events happen when bony parts of the body or medical devices apply pressure to the skin or other soft tissue.

Certain medical settings are more likely to have pressure injuries than others. For example, pressure ulcers are less common among hospitalized patients than those in a long-term care facility. This is likely because pressure ulcers happen more often among immobile patients, those with reduced perfusion, those experiencing malnutrition or those with sensory loss, the StatPearls authors said.

Preventing pressure ulcers or injuries requires strong care team communication and care coordination to ensure adequate patient positioning. Care team members should ensure redistribution of pressure among immobile patients. Through care coordination, care team members can ensure redistribution happens regularly, ideally preventing a pressure injury.

7. Patient identification errors

Patient identification errors are egregious because they are often the genesis of many of the other patient safety events described in this article. Patient identification errors, in which one patient is confused for the other, can lead to the following:

• Incorrect treatment for an individual patient.

• Delays in treatment.
• Blood transfusion errors.
• Medication errors.
• Diagnostic errors.
• Surgical errors.

At the heart of patient identification errors are documentation challenges, according to patient safety nonprofit ECRI. The inability to match the correct patient record to the corresponding individual can lead to matching errors. Issues like physical and digital identifiers, such as wristbands and EHRs, respectively, not aligning or being documented accurately can lead to matching errors.

According to a 2020 Yearbook of Medical Informatics study on the matter, improving patient intake and identification within the EHR, optimizing algorithms to support patient matching and leveraging other matching software might reduce identification errors.

Additionally, safeguards to confirm patient identity, such as downloading patient photos during registration, standardizing naming conventions and standardizing demographic data collection might help.

8. Blood transfusion errors

Blood transfusion errors occur when a patient unintentionally receives the wrong type of blood or experiences another transfusion-related mistake. These errors can happen during blood sample collection, product administration, testing or storage. Adverse blood transfusion incidents can have serious consequences for patient safety and well-being.

In 2024, researchers wrote in the journal Transfusion that these types of errors aren't uncommon. Among the nearly 360 healthcare facilities submitting to the National Healthcare Safety Network Hemovigilance Module between 2014 and 2022, 80 submitted a blood transfusion error report regarding at least one patient at least once per month.

At best, these errors were categorized as near-misses, meaning the mistake did not affect the patient. In these cases, the blood product had to be discarded, resulting in waste.

But at worst, transfusion errors did reach the patient, resulting in an adverse patient safety event, the researchers said.

Like other forms of patient safety errors, blood transfusion errors are often the product of process failures that require more stringent systems to prevent them. Improving staff training, sample labeling and identification, supportive technologies, monitoring and overall administrative procedures could help prevent blood transfusion errors.

9. Documentation and communication errors

Although related to patient identification errors, documentation errors are a distinct type of medical error because they encompass any mistake made in the medical record. Incomplete or inaccurate documentation can lead to incorrect prescribing of medications or treatments.

For example, inaccurate or incomplete documentation of an allergy might cause a clinician to prescribe a medication that contains ingredients a patient is allergic to, resulting in an adverse reaction.

One 2023 report in BJM Health & Care Informatics showed that these errors aren't uncommon, with documentation errors being the cause of 1.3 million injuries annually. A separate JAMA Network Open study showed that about a fifth of patients have detected errors in their EHRs, with 40% of those patients perceiving those mistakes as serious.

Documentation errors can stem from several factors ranging from poor handwriting to transcription errors. Strong staff and clinician training, standardized documentation practices and addressing clinician workload problems might be key preventive practices.

10. Equipment failures

Just as medical errors can stem from human factors and process errors, they can also happen due to the medical equipment and health technology used to support treatments, according to the NIH medical errors resource. Medical equipment failures resulting in patient safety incidents might include equipment design flaws, mishandling, user error or device malfunction.

Preventing equipment failures requires buy-in across the care continuum. While device makers need to practice stringent quality testing, healthcare organizations need strong user training to ensure equipment is set up and placed correctly.

11. Adverse events after discharge

Adverse patient safety events don't just happen inside the four walls of the clinic or hospital; they can happen after discharge, as well.

Adverse events three weeks post-discharge can affect up to one in five patients, according to AHRQ. Most post-discharge patient harms are related to health complications, including the emergence of an HAI or procedural complication.

Most experts say post-discharge patient safety events can be tied back to the transition of care. When care coordination between hospital staff and home healthcare or post-discharge facility staff breaks down, the patient health outcomes are put at risk. Limited health IT interoperability, plus lapses in clinical care team coordination, can cause overall poor transitions of care.

Conversely, data has shown that better, more structured communication during the discharge process can result in better patient outcomes. One 2024 study showed that higher quality of care transitions were linked to lower rates of medication complications post-discharge.

Sara Heath has covered news related to patient engagement and health equity since 2015.