Casebook Vol. 17 no. 1 - January 2009

Head of Medical Services (London), Dr Alison Metcalfe introduces this issue’s selection of case reports, which feature the problems caused by delayed diagnosis

It is no accident that missed or delayed diagnosis features so often in our case reports. After all, diagnostic skills are fundamental to the practice of medicine and establishing a diagnosis, particularly in the early stages of an illness, can be challenging. The learning points we draw from the following cases highlight common failures in the process of arriving at an accurate and timely diagnosis – not taking an adequate history, not carrying out a physical examination, not referring the patient or arranging tests and investigations, not revising the diagnosis when symptoms persist. But what often seems to underlie all these individual failings is a lack of curiosity or spirit of enquiry. As a problem-solving exercise, the art of diagnosis depends on an enquiring mind – in fact, I would say that it cannot be done without one.

If the right questions don’t occur to you, it’s unlikely that you’ll elicit the information you need. The routine of questioning and systems review learnt as a medical student is vital to reaching an informed diagnosis. And if you don’t question at all, you can miss crucial information. This is what happened when Dr G was called out to see Mrs E at her home (see page 18). The patient had a chest complaint. Dr G did not have the benefit of access to Mrs E’s notes, and did not ask about her past medical history. Had he done so, and learned that she had type 2 diabetes, the outcome of this case might have been quite different.

As human beings, we all harbour cognitive biases, which may be relatively harmless in our personal lives but can be dangerous in medicine. Attachment to a false hypothesis, for example, seems to be a common feature of many of the cases of missed diagnosis we see at MPS. The case reports on pages 14 and 17 are fairly typical; the patient is treated for a particular condition over months without apparent success, but faith in the original diagnosis remains firm, and obvious questions are not asked, like “Why is the medication not working? Might there be something else going on here that I haven’t considered?”

There is no shame in making a wrong diagnosis in the process of refining your thinking, or in being stumped by an atypical presentation or a rare condition. Doctors are not expected to be infallible, but they are expected to put themselves in a position to make a reasoned diagnosis. Not posing the right questions, ignoring information available, or sticking unthinkingly to a diagnosis that time and facts should call into question, would be difficult to defend.