What is the Main Cause of Misdiagnosis? Understanding the Complexities

September 29, 2025 •

4 min read

According to the National Academy of Medicine, most people will experience at least one diagnostic error in their lifetime, sometimes with devastating consequences. Pinpointing exactly what is the main cause of misdiagnosis reveals a complicated interplay of human and systemic failures, rather than a single culprit. It’s a systemic puzzle that demands our attention.

Quick Summary

Diagnostic errors are most commonly driven by flaws in clinical judgment, but a complex web of systemic issues contributes significantly. Factors include fragmented care, poor communication between providers, and time pressures during appointments. These issues can delay or prevent an accurate diagnosis, emphasizing the need for comprehensive patient care.

Key Points

Clinical Judgment: Faulty clinical judgment, often driven by cognitive biases like anchoring, is a primary factor in misdiagnosis, not just doctor incompetence.
Systemic Issues: Poor communication between providers, time pressures during appointments, and fragmented care are significant systemic contributors to diagnostic errors.
Testing Problems: Errors during the diagnostic testing process, including ordering the wrong test, lab mistakes, and misinterpreting results, account for a large percentage of errors.
Follow-Up is Key: A lack of proper follow-up after an initial appointment or test can lead to crucial diagnostic delays and missed information.
Patient Advocacy: Being an informed, proactive patient by keeping detailed records, asking questions, and seeking second opinions is a powerful tool against misdiagnosis.

Clinical Judgment and Cognitive Bias: The Leading Human Factor

While the search for a single, primary reason for misdiagnosis is common, studies show that faulty clinical judgment is a dominant factor. Research from Johns Hopkins identified that failures of clinical judgment contributed to over 85% of misdiagnosed cases resulting in serious harm. This does not necessarily point to incompetence but highlights the critical role of human cognition in a high-pressure environment.

The Impact of Cognitive Biases

Cognitive biases are mental shortcuts that can lead to errors in reasoning. In a medical context, these biases can skew a physician's thinking and lead to an incorrect diagnosis. Some key biases include:

Anchoring: Over-relying on the initial piece of information received, such as the first symptom a patient describes, and failing to adjust when presented with new evidence.
Premature Closure: The tendency to accept a diagnosis early in the process and stop considering other possibilities, even if the clinical picture doesn't fully fit.
Availability Heuristic: A doctor overestimates the likelihood of a diagnosis because of a recent similar case, even if it is statistically rare.

Systemic Failures: Beyond the Doctor's Desk

Systemic issues within the healthcare environment play an equally critical, and often overlooked, role in misdiagnosis. These problems create a fragile environment where human error is more likely to occur.

Communication Breakdown

Poor communication is a major cause of medical errors. It can happen at multiple levels:

Provider-to-Provider: Inadequate handoffs between shifts, incomplete patient record transfers, or misinterpretations of specialist recommendations can lead to critical information being lost.
Provider-to-Patient: When doctors don't take enough time to listen to a patient's full story or fail to clearly explain instructions, the patient may not provide a complete and accurate history.

Time Constraints and Workload

Physicians today often face heavy caseloads and limited time for each patient. These pressures can lead to rushed appointments, preventing a thorough history-taking or physical examination. A hurried consultation can cause a doctor to miss subtle but important signs that could point to the correct diagnosis.

The Role of Diagnostic Testing and Follow-Up

Flaws in the testing process and a lack of proper follow-up are also significant factors:

Improper Testing: This can involve ordering the wrong test, lab errors like mixed-up samples, or using faulty equipment. An ECRI analysis found nearly 70% of diagnostic errors occurred during the testing phase.
Misinterpretation of Results: Even with accurate test results, a doctor may misread or misinterpret the findings, leading to an incorrect conclusion.
Lack of Follow-Up: A failure to schedule or track follow-up appointments can mean a diagnosis is missed or delayed, especially if the patient's symptoms evolve over time.

The “Big Three” Misdiagnosed Conditions

Research has identified certain conditions that are frequently misdiagnosed, often with serious consequences. Johns Hopkins researchers identified three major disease categories, which they dubbed the “big three,” that account for nearly three-fourths of all serious harms from diagnostic errors.

Vascular Events: Including stroke and heart attack.
Infections: Such as sepsis and meningitis.
Cancers: With lung cancer and breast cancer being among the most common misdiagnosed types.

How Patients Can Empower Themselves

While the healthcare system has its flaws, patients are not powerless. Here are steps to take:

Be a Detailed Storyteller: Provide a clear, comprehensive, and chronological history of your symptoms. Write down your health issues beforehand to ensure you don't forget anything.
Get a Second Opinion: If you are unsure about a diagnosis, especially for a serious condition, getting a second opinion from another qualified specialist is a vital step.
Keep Your Own Records: Maintain a personal file of your medical records, test results, and notes from appointments. This helps ensure continuity of care, especially if you switch doctors.
Ask Questions: Don't be afraid to ask your doctor questions about why tests are being ordered and what the next steps are. A proactive approach can help catch errors early.

Comparison of Misdiagnosis Causes


Cause Category	Primary Factor	Example of Error	Prevention Strategy
Individual/Cognitive	Faulty Clinical Judgment	Anchoring bias leading to premature diagnosis	Medical training on bias, second opinions
Systemic/Process	Communication Failure	Lost patient records during a hospital transfer	Improved EHR systems, clear communication protocols
Systemic/Testing	Lab/Testing Issues	Sample mix-up or misread test results	Barcoding systems, quality control audits
Systemic/Administrative	Time Constraints	Rushed appointment leading to incomplete physical exam	Allocating adequate time for complex cases
Systemic/Follow-up	Tracking Issues	Patient's test result falls through the cracks	Automated alerts for overdue results

Conclusion: A Multi-Pronged Problem

Understanding what is the main cause of misdiagnosis reveals a problem that is far more nuanced than a simple mistake by a single individual. It is a complex issue rooted in both human cognitive limitations and pervasive systemic flaws. While healthcare organizations must invest in better diagnostic support, patients can also play a crucial role by becoming informed advocates for their own care. This dual approach is essential for reducing the devastating impact of diagnostic errors.

For more insight into diagnostic excellence, refer to the work of the Johns Hopkins Center for Diagnostic Excellence Johns Hopkins Medicine.

Frequently Asked Questions

Cognitive biases are mental shortcuts that can lead a doctor to make an incorrect diagnosis. For example, 'anchoring bias' can cause a doctor to focus too much on the first piece of information and ignore other important signs, which is one of the complex factors when considering what is the main cause of misdiagnosis.

Yes, while not a single cause, systemic issues like rushed appointment times, poor communication between providers, and workflow errors are significant and recurring factors that create an environment ripe for diagnostic errors.

According to Johns Hopkins research, the 'big three' categories most commonly associated with serious misdiagnosis are vascular events (like stroke), infections (like sepsis), and cancers (like lung and breast cancer).

Yes. Clear, detailed communication is essential for an accurate diagnosis. Failure to provide a complete and accurate history of your symptoms can directly contribute to a doctor making an incorrect assessment.

Absolutely. For any serious or complex health issue, seeking a second opinion provides a fresh perspective and can help confirm a diagnosis or identify an error, significantly reducing the risk of a misdiagnosis.

A failure to follow up on symptoms, test results, or changes in a patient's condition is a common cause of delayed or missed diagnoses. It breaks the continuity of care that is essential for accurate health assessments.

In the testing phase, issues like ordering the wrong test, errors during sample collection and handling, or misinterpretation of the test results by the medical professional are major contributors to diagnostic errors.