the art of diagnosis

Tuesday, March 22, 2011

The only certainty of the NCAA basketball tournament is the inability of the experts of the NCAA and the media to predict how the teams will fare once the games begin. The concept of an upset exists only when a team beats the odds and wins unexpectedly. Those odds are based on the observation and experience of people who supposedly know a lot about college basketball but nothing is ever certain until the end of the game. The same can be said for medicine and the art of diagnosis.

Crushing chest pain radiating down the arm, associated with shortness of breath and sweating are the classic symptoms of angina or pain from the heart. Add risk factors like smoking, high blood pressure, high cholesterol and diabetes and the diagnosis is getting easier to make. But what if the patient is only 25? While a heart attack is possible, the diagnosis may be in question. If the patient is female and on the birth control pill, the probability of another diagnosis like pulmonary embolus or blood clot to the lung increases. And if the pain radiates to the back and is described as a ripping sensation, perhaps the diagnosis is an aortic dissection or tear, the disease that killed the actor, John Ritter. Not every patient with chest pain has a potential life threatening illness and not every patient with chest pain needs a heart cath or chest CT. Playing the odds decides what needs to happen next .

Unfortunately, the human body has a tendency to play tricks on patients and their doctors. Indigestion is not always from an upset stomach and jaw pain doesn’t have to be because of a tooth problem. Atypical symptoms can lead the thinking down the wrong diagnostic path and miss the proper diagnosis. And this appreciation that common things aren’t always common should allow the doctor to take caution in ignoring a patient’s complaints.

Ideally, each patient encounter is unique but experience can also be paralyzing. If the doctor’s last patient with chest pain ended up with a dissecting aortic aneurysm, there may be a wariness not to miss that specific diagnosis in the next few patients with chest pain. Extra tests may be ordered that in retrospect may not be needed. Some physicians prescribe to the triple rule out theory of chest pain, where every patient gets checked for heart disease, pulmonary embolus and dissection for fear of missing any of these three potential killers. Technology is great except for the amount of radiation exposure and the potential kidney injuring dye that is required. Fear can be as paralyzing as experience.

The same decision dilemmas exist in belly pain. Before CT scans were easily accessed, clinical skills diagnosed appendicitis. The story of fever, right lower abdominal pain, vomiting (but not too much) and physical exam was almost enough for a surgeon to operate. The fear of missing the diagnosis led to an acceptable mistake rate of 20 percent, meaning the surgeon was right only 4 out of 5 times. This was balanced with the risk of a perforated appendix and the potential for widespread infection. CT scanning changed the game and allowed the diagnosis to be made with more certainty , as long as the CT was done at the appropriate time. If symptoms were present for only a few hours, the CT may appear normal because inflammation had yet to appear. But with the presence of technology, more surgeons wanted the CT to be done before considering an operation. They had been fooled in the past by classic appendicitis symptoms that ended up not being the real thing.

Medicine is all about using personal experience to play the odds. The art of medicine deals with asking just the right question, knowing where to listen for just the right heart sound and deciding just when to order the right test. Even with all the right stuff, the body tries hard to fool the patient and the doctor together. The outcome is never certain until the game is finally played.

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