09/02/202609/02/2026

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Diagnostic Error in Healthcare: Why It Happens and How to Prevent It

Every year, an estimated 12 million Americans experience a diagnostic error in outpatient settings alone. According to the National Academies of Sciences, Engineering, and Medicine (NASEM), diagnostic errors contribute to approximately 10% of all patient deaths and account for up to 17% of preventable adverse events in hospitalized patients.

For decades, patient safety initiatives focused primarily on medication safety and surgical complications. However, clinical organizations now recognize diagnostic error as a critical hazard. Because nursing professionals act as the primary, continuous interface between the patient and the healthcare system, they are uniquely positioned to intercept these errors before they result in catastrophic outcomes.

Medical team wheeling a patient on a gurney

Defining Diagnostic Error: A Two-Pronged Problem

According to NASEM, a diagnostic error is defined as the failure to:

Establish an accurate and timely explanation of the patient’s health problem(s), or
Communicate that explanation to the patient.

This definition shifts the focus from an individual “bad call” by a physician to a wider, systemic breakdown. A diagnostic error is rarely a single, isolated event. Instead, it represents a failure of the clinical team to synthesize data, recognize clinical deterioration, or transition information safely.

The Nursing Scope: While prescribing a medical diagnosis lies within the scope of Advanced Practice Registered Nurses (APRNs) and physicians, Registered Nurses (RNs) bear a heavy legal and clinical responsibility in the diagnostic process. Nurses gather the primary data, monitor evolving clinical baselines, and serve as the patient’s primary advocate.

Clinical Reflection: Have you ever noticed a subtle change in a patient’s neuro status or abdominal assessment that contradicted the documented admitting diagnosis? Did you feel empowered to bring that up to the primary team?

Why Diagnostic Errors Happen: The Cognitive and Systemic Factors

Diagnostic failures are broadly categorized into two intersecting domains: cognitive errors (how clinicians think) and systemic errors (how the healthcare environment is organized).

Cognitive Biases: Shortcuts in Thinking

The human brain naturally relies on mental shortcuts, or heuristics, to make rapid decisions under pressure. In high-stress environments like the emergency department or intensive care unit, these shortcuts can easily degrade into dangerous cognitive biases which could lead to wrong diagnostic testing:

Anchoring Bias (Premature Closure): The tendency to latch onto an initial diagnostic impression early in the assessment, ignoring subsequent data that contradicts it. For example, assuming a patient with history of substance abuse who presents with abdominal pain is simply experiencing drug withdrawal, failing to detect a bowel perforation.
Availability Heuristic: Diagnosing a current patient based on a recent, highly memorable case. If a unit recently experienced a localized outbreak of influenza, a nurse or provider might attribute a patient’s atypical presentation to the flu, missing a atypical presentation of meningitis.
Framing Effects: Allowing the context or source of information to construct a biased viewpoint. If a patient is transferred with a label of “anxious” or “seeking pain medication,” clinicians are statistically more likely to dismiss genuine, physiological symptoms.

Systemic Barriers: Communication and Structural Breakdowns

Even the most vigilant clinician can be set up for failure by systemic vulnerabilities. High-stress environments, chronic understaffing, and administrative burdens severely fragment clinical reasoning:

Communication Failures: Poor handoffs during shift changes or inter-unit transfers are notorious hotbeds for lost diagnostic details.
Information Silos: Essential laboratory or radiological findings that are not personally communicated or highlighted in the Electronic Health Record (EHR) can result in missed opportunities for early intervention.
Hierarchical Barriers: A toxic culture where nurses or junior staff feel intimidated or discouraged from questioning an established medical diagnosis directly suppresses critical clinical insights.

“Even the most vigilant clinician can be set up for failure by systemic vulnerabilities. High-stress environments, chronic understaffing, and administrative burdens severely fragment clinical reasoning.”

The Three Pillars of Nurse-Led Diagnostic Prevention

Preventing diagnostic errors requires active nursing engagement across the entire continuum of patient care.

Preventative Pillar	Clinical Focus	Nurse-Led Action
Objective Assessment	Eliminating cognitive bias and assumptions during patient intake.	Actively seeking objective, physiological data (e.g., trended vitals, physical assessments) rather than relying solely on the documented “admitting diagnosis.”
Assertive Communication	Ensuring critical assessment data is heard and acted upon.	Employing structured communication frameworks (such as SBAR) and escalating clinical concerns through the appropriate chain of command when a patient deteriorates.
Patient Advocacy	Bridging the gap between the medical team and the patient.	Conducting robust “teach-back” sessions with patients and families to verify their understanding of the diagnostic plan, discharge instructions, and follow-up care.

Case Study: The Cost of a Missed Abdominal Aorta Aneurysm

Consider the following scenario based on a common, high-risk diagnostic malpractice trend:

The Clinical Presentation

Patient Y, a 68-year-old male with a history of chronic lower back pain and osteoarthritis, is admitted to an inpatient unit following an elective orthopedic knee surgery. During the night shift, he complains of sudden, sharp, radiating back pain.

The Diagnostic Failure

Assuming the pain is simply an exacerbation of his chronic lower back pain, the night nurse administers the ordered PRN opioid medication. The nurse does not perform a focused abdominal or vascular assessment.

When the morning shift begins, the patient remains hypotensive and tachycardic. The nurse documents these changes but attributes them to uncontrolled pain. Because of “anchoring bias,” the medical team focuses entirely on managing post-operative orthopedic pain. The patient’s emerging physical findings—a pulsating abdominal mass and cold, pale lower extremities—are missed. Twelve hours later, Patient Y’s undiagnosed abdominal aortic aneurysm (AAA) ruptures, resulting in an emergency AAA repair and potential death.

The Stewardship Intervention

Under a protocol focused on diagnostic safety, the nurse’s response shifts entirely:

Broaden the Differential: Recognizing that sudden, sharp, radiating back pain is atypical for post knee arthroscopy, the nurse performs a complete physical assessment, noting a subtle, new difference in the bilateral pedal pulses.
Challenge the Anchor: The nurse refuses to anchor on “back pain” and utilizes the SBAR (Situation, Background, Assessment, Recommendation) framework to call the attending physician.
Use SBAR Assertively: “I have Patient Y who is experiencing acute, sharp, radiating back pain. His blood pressure has dropped to 90/50, and his bilateral pedal pulses are asymmetrical. I am concerned this is not musculoskeletal. I recommend an immediate bedside ultrasound or CT angiogram to rule out a vascular emergency.”

The timely scan reveals the expanding AAA, the vascular surgical team intervenes immediately, and the patient’s life is saved.

Conclusion

A medical diagnosis is not a static label written in stone upon admission. It is a working hypothesis that must be constantly validated, reassessed, and challenged.

Nurses are the eyes and ears of diagnostic safety. By understanding the cognitive biases that cloud judgment and undermine critical communications, nurses serve as the patient advocates when clinical pictures do not align and the ultimate defense against diagnostic error.

References

Gleason, K., Harkless, G., Stanley, J., Olson, A. P. J., & Graber, M. L. (2021). The critical need for nursing education to address the diagnostic process. Nursing Outlook, 69(3), 362–369. https://doi.org/10.1016/j.outlook.2020.12.005

Hall, K. K., Shoemaker-Hunt, S., Hoffman, L., et al. (2020). Diagnostic errors. In Making healthcare safer III: A critical analysis of existing and emerging patient safety practices. Agency for Healthcare Research and Quality. https://www.ncbi.nlm.nih.gov/books/NBK555525/

National Academies of Sciences, Engineering, and Medicine. (2015). Summary. In Improving diagnosis in health care. National Academies Press. https://doi.org/10.17226/21794

Nunez, K. (2024, April 30). What is anchoring bias? Verywell Mind. https://www.verywellmind.com/what-is-the-anchoring-bias-2795029

Author Bio

Leslie Catalano, DNP, RN

Leslie Catalano, DNP, RN, has been a registered nurse since 2005 and spent many years as a travel nurse. She has a Doctorate in Nursing Practice and works at an Associates Degree Nursing Program at her local community college. Along with her passion for nursing and teaching, she loves writing on a variety of nursing topics, including travel nursing, educational modules, and more.

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