Early this year, I wrote an article about one of my patients with chronic abdominal pain who visited the ER of another hospital. The doctors there—who were not familiar with her decade of dyspepsia—ordered a CT scan. Her stomach, gallbladder, intestines and liver were all in pristine condition, but "incidentally noted,"—the report read—"was a 2-centimeter adrenal mass." These adrenalomas are almost always benign, and almost always found only incidentally. They even have their very own appellation—the incidentaloma.

Nevertheless, I felt boxed into a clinical corner, forced to order expensive and complicated tests to rule out the minute chance of malignancy. The arduous process completely overwhelmed and panicked the patient, and we were never able to get to the actual diseases that she already had—diabetes, depression, and arthritis.

Two months later, I found myself in a Washington D.C. conference room, testifying before a razor-sharp committee of academics from law, nursing, medicine, philosophy, ethics, divinity, research, and government. This was a Presidential Commission for the Study of Bioethical Issues panel on incidental findings. The ethical considerations of incidental findings turned out to be much broader and more intriguing than I, as a ordinary primary care doc, had ever imagined.

In clinical medicine, we worry mainly about things that are uncovered when we doctors order tests and find other things—that's what happened to my patient. It turns out that incidental findings are hardly incidental—they turn up in about a third of CT scans. In the case of abdominal CTs for trauma patients, the number of incidental findings can supersede that of trauma findings—and follow-up is notably spotty. In this age of defensive medicine, routine MRIs, and bundled tests, incidental findings are a daily occurrence.

But there are two other areas in which incidental findings are of escalating concern: research trials and direct-to-consumer medical testing.

Biomedical research is critical to the advancement of medicine, and the unsung heroes are the legions of volunteers who submit to all manner of investigation, mainly for the benefit of society, rather than themselves. But these countless lab tests, CT scans, and MRIs done for specific research questions are as prone to incidental findings as tests done in the clinical world, and pose unique ethical dilemmas.

For example, when a CT is ordered in the clinical world—as for my patient—a trained radiologist evaluates every aspect of the CT, no matter what the initial reason for the scan. But in the research world, these CTs might be of a low resolution, designed to focus on the particular research question, and often interpreted by a research scientist trained to examine just that one thing.

Are research scientists obliged to have a radiologist thoroughly evaluate each scan? Are they obliged to use the high-level resolution scans on par with those in the clinical world? These technicalities may seem like hair-splitting, but they could be prohibitive enough to cancel a research study.