What everyone should know about lab tests

by Shannon Haymond, Scientific American, 9 May 2016

Dr Haymond is the director of a medical laboratory at a children’s hospital in Chicago, and an Associate Professor of Pathology at Northwestern University.

She notes a new study suggests that medical error causes 251,000 deaths in the United States each year, making it the third largest cause of death.

One proposal defines a medical error as “an act of omission or commission in planning or execution that contributes or could contribute to an unintended result.”

By this definition, failures in laboratory tests certainly qualify. Lab test failures contribute to delayed or wrong diagnoses and unnecessary costs and care.  For context, a 2014 study estimated that diagnostic errors happen about 12 million times per year in U.S. outpatients. This represents 1 in 20 adults. 

Dr Haymond says that as a laboratory director and medical educator “I frequently experience misperceptions that diagnostic laboratory tests are always correct and useful, even though a primary tenant of my field is ‘no test performs perfectly’.”

She has practical advice for patients to “be informed about the possible problems that could arise and what to ask to try to avoid them.”

Using the right test is critical to obtaining desired information

Using the right sample is key to getting a valid result

Lab errors happen despite a strong focus on quality operations

Results must be put into context

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