Wednesday, November 14, 2007

rule out

Let me tell those of you who are not physicians a little bit about medical school.
Those big thick books about anatomy and physiology and biochemistry and pathology and lots of other things are full of information. When I was in med school, I think computers had been invented, but I'd never seen one and never dreamed of owning one. Nor did I dream that all the information in those big thick books would fit on a piece of plastic the size of my fingernail, and it never dawned on me that this information would be of interest to anyone besides a physician and perhaps the patient with the problem described in the book.
That said, the 2nd year of med school is pretty much all about what can go wrong with your body - pathology. I distinctly remember going home every night pretty sure that I had some strange tropical disease that was very rare but whose symptoms were headache and fatigue, things that are common to the average person. But I attached those symptoms to the disease I had just studied. Every night, pretty much, no lie. Later, as a pediatric resident, my wife would ask me at what age our children would need to be before she could stop worrying about the diseases I came home and talked about having just seen in the hospital or clinic that day - cancer, meningitis, cystic fibrosis, you name it.
Well, the thing that helped was something we are taught, or at least we used to be taught, in med school. The differential diagnosis is a list of the possible things that could cause the symptoms and findings in a person a doctor is seeing. If you watch House, that's what he writes on the board, weird ones and all. Then the most difficult and gratifying part begins, ruling out various things on the list that the patient doesn't have. "Rule out" used to be a diagnosis, actually, or we used it as one. It was a temporary diagnosis if you thought they had it but the test wasn't in yet, like "rule out strep throat" or "rule out meningitis". Then there are the times it was used to mean you didn't really think they had something but they, or someone else, thought they did. "Rule out brain tumor" was a justification for a ct scan for a headache. It gave the reason for the test, but was more often code for "I don't think he's got one but I have to test for it".
Now we aren't allowed to use "rule out" as a diagnosis, we have to list the symptoms or signs, or we have to say "suspect", like "sepsis suspect" instead of "rule out sepsis". Sounds legal, or illegal.
But the "rule out" is what the average person Googling his or her symptoms on the computer doesn't have. One gets a list of the differential diagnosis, admittedly longer than one I would come up with generally, but doesn't help with the "rule out". Why you DON'T have MRSA. Why your headaches are not likely to be from a brain tumor. Why your fatigue is lack of sleep rather than African sleeping sickness, or even West Nile virus. Ruling out is very important. It's as much an exercise in common sense as anything. Discernment might be a better word. And a base of knowledge is necessary to "rule out" things. One doesn't always have to have a degree in medicine to do most of the "ruling out". An experienced mom or grandma can do it quickly and efficiently. Unfortunately, many have lost their common sense in the face of the daunting amount of possible diagnoses that exist. It was so much simpler when all we knew was appendicitis or strep throat or earache. Now there's intussusception, MRSA, and cholesteatoma to add to the list. There's IBS, IBD, CRAP, UC, CD, and a host of other acronyms to consider when a kid has a belly ache. There's mono and sleep apnea to consider with big tonsils, and auditory nerve gliomas to account for when considering the cause of hearing loss.
The best thing I learned in med school is "common things occur commonly". I've heard preachers use a variation on this when telling people how to study the Bible - "the plain things are the main things, and the main things are the plain things". Another adage that has helped is "when you hear hoofbeats, you should think of horses, not zebras".
I'm not advocating for patients to quit researching their problems, believe me I've been bailed out plenty of times by a patient whose interest opened up an area I hadn't considered. And patients should be more informed about diseases that they have, even more so than the doctor in some cases.
Finally, and in summary, having information in the form of lists of possible diseases whose symptoms matched the search criteria you listed dumped on you like a load of rock for you to sift through hoping to find something meaningful is not particularly helpful. You need to learn the art of "ruling out" certain things. This requires work, and can be helped along by your local medical doctor (LMD). But to learn it, regardless of the work, and even if it involves trusting someone else's expertise, is a source of peace for many.

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