Case guide

UPDATED FEB 2026

Misdiagnosis Malpractice

Part of the Medical Malpractice investigation

The short answer

Diagnostic errors — misdiagnosis, delayed diagnosis, and failure to diagnose — are the most common category of medical malpractice and the leading cause of serious malpractice-related harm. When a physician fails to identify a time-critical condition and that failure allows the disease to progress, the consequences can be irreversible.

People's Justice Research TeamUpdated February 20, 2026Fact-checked

Verified against court and regulatory records · No upfront fees · Your information is never sold

Free Case Review

Check your eligibility — free

Answer 2-3 quick questions to review your potential case.

Free · Confidential · About 2 minutes · A case specialist responds within 1 business day

Your answers are never sold or shared without your consent.

The Scope of Diagnostic Error

BMJ Quality and Safety estimates that approximately 12 million Americans experience a diagnostic error in outpatient settings annually. Approximately 40,000 to 80,000 deaths in U.S. hospitals each year are attributable to diagnostic errors. Despite this scale, diagnostic malpractice claims are among the most challenging to prosecute because the core question — whether a competent physician in the same situation would have reached the correct diagnosis — requires nuanced expert testimony about clinical reasoning and differential diagnosis.

Missed Cancer Diagnoses

Cancer misdiagnosis is the single most common basis for medical malpractice claims in the United States. Breast cancer, lung cancer, colorectal cancer, and prostate cancer are the most frequently misdiagnosed. In these cases, an abnormality visible on imaging or biopsy is attributed to a benign cause, a screening recommendation is not made, or an abnormal test result is not followed up — allowing a curable early-stage cancer to advance to a late-stage disease with dramatically worse prognosis. The plaintiff must show that, had the cancer been correctly diagnosed at the earlier time point, the treatment and prognosis would have been materially better.

Missed Heart Attack, Stroke, and Pulmonary Embolism

Acute myocardial infarction (heart attack), ischemic stroke, and pulmonary embolism are all time-critical emergencies where delays of hours or even minutes can mean the difference between full recovery and permanent disability or death. Heart attacks presenting with atypical symptoms — jaw pain, back pain, nausea in women — are routinely misattributed to gastrointestinal or musculoskeletal causes. Strokes presenting with dizziness, headache, or subtle speech changes are misdiagnosed as migraines or vertigo. Pulmonary embolisms presenting with shortness of breath and pleuritic chest pain are labeled as anxiety or musculoskeletal chest wall pain. In each case, the failure to order appropriate diagnostic tests — EKG and troponin for MI, CT angiography for PE, CT or MRI for stroke — is the central act of negligence.

Key data

Data & Statistics

2 SOURCED FIGURES

12 million Americans experience diagnostic errors in outpatient settings annually

BMJ Quality and Safety

Cancer is the most common basis for U.S. medical malpractice claims

PIAA Data Sharing Project

FAQ

Frequently Asked Questions

12 QUESTIONS

Medical malpractice occurs when a healthcare provider — physician, surgeon, nurse, hospital, or other licensed provider — deviates from the accepted standard of care and that deviation causes preventable harm to a patient. The standard of care is defined as what a reasonably competent provider in the same specialty would have done under the same or similar circumstances. Malpractice is not simply a bad outcome — medicine involves inherent risks, and a patient can suffer a serious complication even with perfectly delivered care. To be malpractice, the provider must have acted negligently: doing something a competent provider would not have done, or failing to do something a competent provider would have done.

Dive deeper

Related Guides

24 GUIDES

The full investigation

Part of the Medical Malpractice Investigation