Of course real life patients can be challenging and give a non-specific history etc. But say you have a patient who comes to your department with a STEMI-like EKG, and he tells you that his chest pain is extremely severe, somewhat ripping, and radiates to his back. Now even if that guy has a low pretest probability of having aortic dissection (no other risk factors, no clinical findings, i.e. 1/3 points only), and you know that most of these patients will "just" have an MI, you will have to get him a CT scan before you throw antiplatelets and anticoagulants in his direction and take him to the cath lab, because in this case your decision might carry massive consequences. The problem is that the exam does not let you think like that. Yes, an MI will certainly still be the most probable diagnosis, but what does that mean test-wise? Forget about your gut feeling and go back to guidelines where 1/3 points equals D-dimer+CXR+transthoracic echocardiography while his myocardium is dying? Am I allowed to be flexible like a clinician needs to be? I don't think I am the only one here who gets confused because of the kind of wording used by the NBME. As Cabergoline wrote, sometimes you do multiple things at once. For example, there are a lot of patients in whom you initially do not know whether the diagnosis is COPD exacerbation or decompensated HF, and the auscultation is equivocal. All those old fellas have diastolic dysfunction anyway. So you obviously throw both loop diuretics and beta 2 agonists (and needless to say, oxygen) their way at the same time, because that is how you do it. You do not just let the patient sit and have dyspnea until you have that CXR, which is more or less useless if he is lying down anyway. But you order it. You order the ABG too. But you don't have to do it in a specific order. They're all part of "B" in ABCDE.
