We go to the doctor because we’re feeling that something is wrong, that something isn’t right.
We expect them to figure out what it is. But sometimes the doctor misses it entirely. The condition goes unnamed, and by the time anyone catches it, real damage has already been done. f
In Arizona, a doctor’s failure to diagnose can be grounds for a medical malpractice lawsuit if that failure caused you harm.
Still, not every missed diagnosis counts as malpractice, so it’s worth understanding what the Arizona law actually requires before you assume you have a case.
What Is a Failure to Diagnose Lawsuit?
Failure to diagnose, misdiagnosis, and delayed diagnosis are related but distinct problems.
A failure to diagnose means the provider never identified the condition at all. A misdiagnosis means they identified the wrong one. A delayed diagnosis means they eventually got it right, but only after time that mattered had already passed.
All three can support a malpractice claim in Arizona under the same legal standard: the provider failed to meet the applicable standard of care under A.R.S. § 12-563, and that failure caused your injury.
A wrong or missed diagnosis by itself isn’t enough. Medicine isn’t an exact science, and a provider can make a reasonable call that turns out to be wrong without it being negligence.
Example:
A patient goes to the doctor with a persistent cough and unexplained weight loss. The doctor examines them, finds nothing alarming, and sends them home without ordering imaging or bloodwork. Months later, the patient is diagnosed with lung cancer that had already progressed, and an earlier workup likely would have caught it.
How Common Is This?
A 2023 study from Johns Hopkins’ Armstrong Institute Center for Diagnostic Excellence, published in BMJ Quality & Safety, estimated that roughly 795,000 Americans die or are permanently disabled every year because of diagnostic error across all care settings, from primary care to hospitals to emergency departments.
Of those harms, about 371,000 involve death and 424,000 involve permanent disability.
The same research found that five conditions account for nearly 39% of all serious diagnostic-error harm: stroke, sepsis, pneumonia, blood clots, and lung cancer.
Common Conditions Doctors Most Often Fail to Diagnose, Missed or Delayed
Some conditions show up in failure to diagnose cases far more than others, usually because their early symptoms look like something routine.
Among patients presenting with symptoms of a major vascular event, infection, or cancer, 1 in 10 get misdiagnosed, and of those, about 54% suffer permanent disability or death. That figure comes from a peer-reviewed analysis published in the journal Diagnosis, and it’s worth reading in full here.
Stroke — Stroke symptoms like sudden confusion, slurred speech, or dizziness can easily be mistaken for something minor, especially when they come and go.
Diagnostic errors occur in about 8.7% of stroke cases, a rate researchers found runs 5 to 10 times higher than heart attack’s despite the two conditions being roughly equally common.
Sepsis — Sepsis often starts out looking like a routine infection, which makes it easy to underestimate until a patient’s condition suddenly deteriorates.
Sepsis is misdiagnosed in an estimated 9.5% of cases, with about 5.4% of those patients suffering serious, permanent harm as a result.
Lung cancer — Early lung cancer symptoms, like a persistent cough or fatigue, are often chalked up to less serious causes, which delays the imaging or biopsy that would catch it.
Lung cancer is one of the three leading conditions behind serious diagnostic-error harm, and cancers overall account for nearly 38% of all deaths and permanent disabilities tied to the “Big Three” misdiagnosed disease categories.
Aortic aneurysm or dissection — This condition can present as back or chest pain that mimics a muscle strain, right up until the vessel ruptures.
Pulmonary embolism — Symptoms like shortness of breath or leg swelling are vague enough that they often get attributed to something far less serious.
Pulmonary embolism goes undetected on the first visit in an estimated 20% of cases.
Spinal abscess — This condition is rare enough that many providers don’t consider it until symptoms are severe, which is part of why it’s missed so often.
Spinal abscess has the highest documented miss rate of any commonly misdiagnosed condition, with diagnostic errors occurring in roughly 62% of cases and serious harm resulting in about 36% of those.
Heart attack — Heart attack symptoms aren’t always the classic chest pain, and atypical presentations, especially in women, are more likely to be dismissed.
Even so, heart attack has the lowest miss rate of the group at around 2%, thanks to decades of investment in EKGs and biomarker testing.
Where This Happens: Primary Care, Urgent Care, and the ER
Failure to diagnose claims can arise anywhere you receive care, and Arizona treats some of these settings differently.
Urgent care clinics are licensed as outpatient treatment centers, not emergency departments, so claims against them generally use the standard “preponderance of the evidence” burden of proof.
Emergency departments are different. Under A.R.S. § 12-572, claims involving care provided to a hospital patient under the federal Emergency Medical Treatment and Labor Act (EMTALA) require clear and convincing evidence, a higher bar than most malpractice cases.
What You Need to Prove
Building a failure to diagnose case usually starts with the medical chart: reported symptoms, vital signs, exams performed, tests ordered, results, and discharge instructions.
Later records matter too, since they show what happened after the original visit and how the eventual diagnosis was made.
Medical experts are typically essential. Under A.R.S. § 12-2603, Arizona requires a preliminary expert opinion affidavit addressing the standard of care, the alleged failure, and how it caused your harm.
That expert also has to meet Arizona’s qualification requirements under A.R.S. § 12-2604, generally meaning they actively practice or teach in the same specialty as the provider involved.
You’ll also need to show that the delay made a difference.
If a diagnosis is missed but caught soon enough that treatment and outcome are unaffected, there may not be a viable claim even though a mistake occurred.
How Long Do You Have to File?
Arizona generally gives you two years from when your cause of action accrues under A.R.S. § 12-542.
Because the harm from a missed diagnosis doesn’t always surface right away, Arizona courts apply the discovery rule, meaning the clock can start when you knew, or reasonably should have known, that negligence caused your injury rather than the date of the original visit.
If a government or public entity is involved, such as a county hospital, the deadlines are much shorter: a notice of claim within 180 days under A.R.S. § 12-821.01, and the lawsuit itself generally has to be filed within one year under A.R.S. § 12-821.
What You Can Recover
Damages in an Arizona failure to diagnose case can include past and future medical expenses, lost wages, reduced earning capacity, and pain and suffering, depending on how the delay affected your treatment and recovery.
If a missed or delayed diagnosis results in death, surviving family members may have a separate wrongful death claim under A.R.S. § 12-611.
Unlike most states, Arizona’s constitution prohibits capping compensatory damages in personal injury and wrongful death cases under Article 2, Section 31, so there’s no artificial ceiling on what a jury can award.
The Bottom Line
A failure to diagnose can support a medical malpractice claim in Arizona, but proving it takes more than showing the diagnosis was wrong or came late.
You need to show the provider fell below the standard of care and that the delay actually caused harm. Firms like Miller Kory Rowe medical malpractice attorneys handle these cases regularly and can help you figure out whether what happened to you meets that standard.
If you believe a missed or delayed diagnosis caused you or a loved one harm, a free consultation can help you understand where you stand. Call (602) 648-4045 to talk to someone about your case.
Frequently Asked Questions
Q: Is failure to diagnose the same as misdiagnosis?
A: Related but different. A failure to diagnose means the condition was never identified. A misdiagnosis means the wrong condition was identified. Both can support a malpractice claim under the same legal standard.
Q: Is every missed diagnosis medical malpractice?
A: No. A provider can miss or delay a diagnosis without being negligent. A claim generally requires showing the provider fell below the standard of care and that the failure caused harm.
Q: Is it harder to sue an ER than urgent care or a primary care doctor in Arizona?
A: Certain ER cases can be, since A.R.S. § 12-572 applies a clear and convincing evidence standard to specified emergency care. Whether it applies depends on the circumstances of the treatment.
Q: Do I need an expert witness?
A: Generally yes. Arizona requires a preliminary expert opinion affidavit early in the case, and the expert must meet specific qualifications tied to the same specialty as the provider involved.
Q: How long do I have to file a failure to diagnose lawsuit in Arizona?
A: Generally two years under A.R.S. § 12-542, though the discovery rule can extend that. Claims against public entities have a much shorter 180-day notice requirement and a one-year filing deadline.
Q: What can I recover in an Arizona failure to diagnose case?
A: Medical expenses, lost income, reduced earning capacity, and pain and suffering, depending on the harm. Arizona doesn’t cap compensatory damages, and a death caused by a missed diagnosis may support a separate wrongful death claim.