A biopsy sample smaller than a pinhead was placed on a sterile towel at the Mayo Clinic in Rochester last year and whisked to a pathology lab. On arrival, the dab of human tissue was nowhere to be found.
"We were never able to discern what exactly happened to that specimen," said Dr. Tim Morgenthaler, Mayo's chief patient safety officer.
Nor could they test the sample to solve the mystery of their patient's illness.
The misplacing of irreplaceable biological specimens has proved to be a vexing problem for Minnesota hospitals, which reported 31 instances in the 12 months that ended last Oct. 6.
The state's 13th annual report on hospital "adverse events," released Thursday, included 336 reportable mistakes, including operations on the wrong body parts and disabling medication errors. But few were as common as lost tissue samples, which also can have serious consequences.
"That small little tiny one-millimeter polyp belongs to a patient," said Dr. Rahul Koranne, chief medical officer of the Minnesota Hospital Association, which released the report with the Minnesota Department of Health. "And that could have been a critical data point that could have meant the diagnosis of a cancer vs. a diagnosis of health."
The report included four adverse events that resulted in deaths — three from patient falls and one from a medication error — and 106 that led to severe injuries. As in most years, the most common adverse events were pressure ulcers, often called bed sores, and patient falls. Four injuries were reported last year because patients had not received follow-up instructions or test results.
Since 2005, Minnesota hospitals have publicly reported on more than two dozen errors dubbed "never events," because they theoretically were preventable with proper safety precautions.