A man walks into an emergency room with crushing abdominal pain. He waits three hours to be seen. The emergency physician spends ten minutes with him, prods his abdomen briefly, diagnoses gastritis, and sends him home with antacids and instructions to follow up with his primary care doctor. Fourteen hours later he's back, this time by ambulance, with a ruptured appendix and peritonitis spreading through his abdominal cavity. He spends two weeks in the ICU. The infection nearly kills him.
That's a failure to diagnose case. Here's what makes it—or breaks it—legally.
Not Every Miss Is Malpractice
Medicine involves uncertainty. Patients don't arrive with their diagnoses printed on their foreheads. Doctors gather information, consider possibilities, make judgments based on incomplete data, and sometimes get it wrong. Not every wrong answer is negligence.
The question isn't whether the doctor was right. It's whether a reasonably competent doctor, facing the same information, would have reached the correct diagnosis.
In the appendicitis case, the emergency physician had a patient with severe abdominal pain—a symptom that puts appendicitis squarely on the list of possibilities. Did he take a thorough history? Did he ask about the pain's location, quality, and progression? Did he perform a complete abdominal examination? Did he order basic lab work that might have shown elevated white blood cells? Did he consider appendicitis in his thinking and rule it out through appropriate workup?
If the answer to these questions is no—if a ten-minute encounter and a diagnosis of gastritis is all this patient got—then the care fell below the standard. That's the foundation of a case.
Differential Diagnosis: Where Failures Often Lie
When physicians evaluate patients, they generate a list of conditions that could explain the symptoms—what's called a differential diagnosis. Then they systematically work through that list, gathering information and ordering tests to rule conditions in or out until they arrive at the most likely answer.
Failure to diagnose claims often focus on two types of failures within this process. The first is failing to put the correct diagnosis on the list at all. A physician who never considers heart attack in a 45-year-old woman with jaw pain, shortness of breath, and nausea has already failed—she's excluded the correct answer before doing any evaluation. The second is putting the diagnosis on the list but failing to investigate it properly. Writing "rule out appendicitis" in a chart and then not ordering the CT scan or surgical consult that would actually rule it out means the differential diagnosis was just an academic exercise rather than a diagnostic tool.
The Testing Problem
Consider another case: a 55-year-old man sees his doctor for persistent fatigue and unintentional weight loss. Basic blood work is ordered, comes back normal, and the patient is told nothing is wrong. A year later he's diagnosed with pancreatic cancer—stage IV, inoperable, months to live.
Normal blood work doesn't rule out cancer. Unexplained weight loss in a middle-aged adult is a red flag that warrants imaging, not reassurance. The testing was inadequate for the clinical presentation, and that inadequacy delayed a diagnosis until it was too late to matter.
The Communication Problem
A radiologist reads a chest X-ray and notes "suspicious pulmonary nodule, recommend CT for further evaluation." The report goes into the electronic medical record. No one calls the patient. No CT gets scheduled. The primary care physician never opens the report, and the patient—who was told he'd hear something if there was a problem—assumes silence means everything was fine.
Two years later, a new X-ray reveals lung cancer that has metastasized to his brain. Looking back, the nodule was there all along in that first study, documented and then ignored.
The failure here wasn't detection—the radiologist found the problem. The failure was in the system that let a critical finding sit in a chart without triggering action. Someone should have communicated the results to the patient. Someone should have scheduled the follow-up scan. Someone should have had systems in place to ensure abnormal findings don't fall through cracks. Instead, everyone assumed someone else was handling it, and a treatable cancer became a death sentence.
Proving Your Case
You'll need medical records documenting what you reported, what examination was performed, what tests were ordered and not ordered, and what diagnoses were considered. You'll need expert witnesses who can establish what a competent physician should have done differently and explain it in terms a jury can understand. You'll need evidence connecting the delayed diagnosis to your harm—showing that earlier detection would have changed your outcome, not just your experience.
That last element matters. If your condition would have progressed identically regardless of when it was diagnosed—if no treatment would have helped—there's no case. The value of a failure to diagnose claim depends entirely on how much the delay changed your outcome: what additional treatment you needed, what suffering you endured, what life expectancy you lost because the diagnosis came too late.