Currently listening to David Baldacci – Redemption. The mystery novel, like many others, demonstrates important diagnostic principles.

The story is one of missed diagnosis – in the mystery the detective is asked to reopen a case. Once he reconsiders his first murder case (13 years later), he recognizes mistakes that he made. He carefully reanalyzes several pieces of evidence considering how they fit the original assumptions.

Once he decides that he needs to reinvestigate, he returns to the scenes of the crime. He re-examines the evidence; he once again interviews potential suspects; he focuses on inconsistencies.

In medicine we should do that regularly. When in doubt, return to the patient, retake the history and physical examination. Ask yourself, if the current diagnosis is wrong, what else could be the proper diagnosis.

When asked about another detective for whom he has low regard, he opines that the other detective is adequate but prone to focusing on the easiest explanation, and ignoring the inconsistencies.

This reminds me of an Agatha Christie quote:

“It often seems to me that’s all detective work is, wiping out your false starts and beginning again.”

“Yes, it is very true, that. And it is just what some people will not do. They conceive a certain theory, and everything has to fit into that theory. If one little fact will not fit it, they throw it aside. But it is always the facts that will not fit in that are significant.”
? Agatha Christie, Death on the Nile

We can learn much about diagnostic errors and the diagnostic process from mystery fiction. To do so requires that we relate the detective process to our own diagnostic process. This seems like a natural progression, since being an internist starts with detective work. Remember that many of your best diagnostic successes come on “cold cases”. As in this book, when a previous diagnosis does not make sense, consider reopening the diagnostic process as a “cold case”.