…but sometimes, it just might be a zebra!

Our good moderator YankeeBeckham asked on the forum if I could write about some of the more exotic medical cases that I’ve encountered during my career. He asked me to write a bit about “zebras”. By zebras YankeeBeckham refers to this old medical saying: “When you hear hoofbeats, think horses, not zebras”. Another way to put it: The most common diseases are most common. So, if someone has headache, it’s more likely to be migraine than a brain tumor.

A couple of zebras come to mind. Early in my career, I was on-call in a rural healthcare center as a primary care physician. A patient was brought in, he was unconscious and had no measurable blood pressure and was in shock. He was a man in his 50’s. The usual horse in this case would be a coronary heart attack.

After the usual ABC (Airway, Breathing, Circulation) check, with fluid resuscitation, I got the blood pressure back to measurable levels, and the patient regained consciousness. He spoke coherently, was orientated and exhibited no neuro deficits, so neurological causes were pretty much excluded. I called for transportation to the nearest hospital and meanwhile did some basic diagnostic work-up in order to figure out what was causing this. The ECG did not show signs of myocardial infarction (coronary). Blood glucose was normal. I did not have any lab services at my disposal. Periphery was cold, heartbeat was rapid, suggesting possibly shock due to bleeding.

He wasn’t bleeding externally, so I figured maybe a bleeding ulcer. There was no guarding upon palpation of the abdomen, although he did complain both chest pain and abdominal pain. I did a rectal examination, which did not reveal signs of blood, speaking against gastrointestinal bleeding. I was puzzled. The patient was clearly bleeding and required more and more i.v. fluids to maintain blood pressure.

This led me to think of a zebra: Aortic dissection or rupture. I called the surgeon in the central hospital and explained that this might be a case of aortic dissection, though I couldn’t be sure. It later turned out that this was indeed the diagnosis, and the patient underwent emergency surgery and survived. Aortic dissection is a condition in which parts of the wall of the aorta are separated and bleeding between those layers occurs. Apparently this was a case in which the outer wall was ruptured and as a result the bleeding was significant in volume, leading to shock. Not every primary care physician gets to see a case of aortic dissection.

That’s it for now, more zebras later.

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