Perspective: Radiology discrepancies: What’s the “miss rate”? Who’s responsible?

By Charles A. Pilcher MD FACEP
December, 2015

How often does a radiologist miss an x-ray finding? What happens when they do? Should ordering physicians view all images themselves? What if there’s a disagreement? Who’s responsible? And can we determine a standard of care? When there’s a “miss,” what procedures and guidelines should be followed?

These questions are frequently part of malpractice litigation. That physicians may occasionally miss a finding on an x-ray or other radiographic image is not surprising. But how often does it happen? And how often does it matter? Sometimes the “miss” is important. Often it’s not. Usually it’s caught and appropriately addressed. Rarely it is not caught, and if the finding is important, a lawsuit may result.

Emergency physicians have informally read the x-rays they order on their own patients since EM became a specialty 36 years ago. Most of them also read (or at least look at) any advanced imaging they order, like CT and MRI. Many ED physicians actually do their own ultrasound studies. In the early years, this skill was needed because radiologists were often only available during “bankers’ hours.” The role of the radiologist was one of quality control (QC), over-reading the films the next business day (and collecting the fee, long after the ED doc had made a diagnosis and treated the patient based on his or her own interpretation). “Discrepancy reports” became the basis for assuring the accuracy of images read, comparing the impression of the ED physician to that of the radiologist. This became the basis for quality control in ED imaging.

Fortunately, the QC role has evolved over time into a much more collaborative relationship between radiologists and ED (or other) treating physicians. Reading x-rays, getting feedback and discussing findings with radiologists improves the quality of care provided in the ED. This symbiotic relationship is promoted by the American College of Emergency Physicians in their Policy Statement on “Interpretation of Imaging Diagnostic Studies.” Here is an excerpt:

The American College of Emergency Physicians (ACEP) believes that the quality of patient care is enhanced when emergency physicians interpret and record the results of the diagnostic studies they order at the time of service. While the interpretation of diagnostic studies by other specialists may be important to patient care, the treating emergency physician is in the best position to fully integrate in a timely and effective manner all relevant clinical and other available information to optimize the quality of patient care in the emergency department (ED).

The policy further emphasizes the importance of documenting any and all readings and any discrepancies. Read the full policy here.

Short of real-time communication on every radiologic study, the “discrepancy report” process works like this: The ED physician documents his/her preliminary impression of an image for the benefit of the over-reading radiologist. He/she can then determine if there is agreement or if something was missed. If a discrepancy is found, the radiologist notifies the ED and the ED notifies the patient and provides instructions appropriate to the situation. Both parties document the discrepancy and the resolution.

So what is the discrepancy rate between ED physicians and radiologists?

Reported studies of discrepancies between ED and radiology readings almost always assume the accuracy of the radiologist’s interpretation and use that to determine the “discrepancy rate.” It varies from less than 1% to over 15%, depending on the definition of a “discrepancy.”

But are the radiologists always right?

One of the most comprehensive inter-specialty studies was done In 2003 by Benger and Lyburn. They published an analysis of over 19,000 ED visits with nearly 12,000 x-rays. They found 175 discrepancies (1.5%). Of these 175 patients, 136 (78%) were subsequently shown to have been incorrectly interpreted in the ED (i.e., false negatives). Forty (23%) required a change in management. However, in 39 of the 175 discrepancies, the ED physician’s interpretation was deemed to be correct, with 16 (41%) of these patients requiring additional investigations or follow-up.

When this happens, it is almost always a result of the ED physician having a clinical context and knowing what to look for. When this type of discrepancy is noted, it should result in a call from the ED physician to the radiologist with a request to re-assess the interpretation. If the radiologist agrees, he/she should dictate an “Addendum” and document the communication with the ED to confirm that proper care has been provided.

Yes, Virginia, radiologists can be wrong. In 1 out of 5 cases the emergency physician’s interpretation is the correct one. As the song “Lean On Me” says:

You just call on me, brother, when you need a hand
We all need somebody to lean on
I just might have a problem that you’ll understand
We all need somebody to lean on
Lean on me when you’re not strong
And I’ll be your friend, I’ll help you carry on
For it won’t be long
‘Til I’m gonna need somebody to lean on

Bill Withers, 1972

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