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Avoid Confusion: The Most Classic, The Most Likely

During our career in AMC MCQ Exam preparation courses, whether online or face to face, we have frequently encountered a very common mistake among the candidates preparing for the exam. We call it playing “Sherlock Holmes”. Yes true: medical conditions do not present exactly the same way written in the text books. There are always atypical presentations and diagnostic dilemmas. This is the reason why so many paraclinic tests, consultants and different fields in the medicine exist.  In real world, nothing is that straight forward. But for the purpose of the AMC MCQ CAT exam things are different. This exam is designed for baby doctors. By baby doctors, we mean interns, HMOs and GPs, and these doctors are not expected to go in depth. Baby doctors are required to be familiar only with classic presentations of diseases and medical conditions, not exceptions, not case reports, and not rare entities.

To avoid wasting time and confusion during your hard journey of preparing for this exam, stay cool and always repeat to yourself that no matter what your medical background is at home, you are a baby doctor here. Don’t forget this. Baby doctors are not expected to know more than they are expected to know. So think simple and classic and go easy.

Does it mean that you will be asked only simple diagnoses? Definitely not, but over 80% of diagnoses you need to know are easy as piece of cake, so why we put a lot of effort for gaining just a little? You need a pass score of 250. To be definitely on the safe side, you only need to clear 60-65% of questions in exam. So why don’t we put most of our time and energy in what is going to pay more?

Let’s make it short and start with an example.

You are an HMO in the emergency department. A 50-year-old man, who is diabetic and also on warfarin for AF or previous DVT or whatever indication is brought to the emergency department with right calf pain and swelling. He is running a fever and the calf is red on inspection and tender and warm to touch. What is the most likely diagnosis?

Let’s go through the options:

Could it be hematoma? Yes. Because he is on warfarin. Does hematoma causes fever? If it becomes complicated and infected yes. But remember: forget about ‘but’s and ‘if’s. For the purpose of the exam hematoma does not present with fever. So cross it out.

Could it be DVT? Absolutely yes. Classical presentation. BUT this patient is already on warfarin. Is it possible, in real world, to develop DVT while on warfarin? Absolutely yes. But the answer for the purpose of the exam would be: “this guy is already on prophylaxis or treatment with warfarin, so although DVT can be a possibility, it is less likely.

Could it be cellulitis? Yes. And this is the correct answer. Why? Because even if we are blindfolded and not able to see the lesion and its borders (sharp in cellulitis and vague in DVT), just by knowing that the patient is already on warfarin, we consider DVT less likely, even slightly, compared to DVT. At least for the purpose of the exam. And ask yourself? Why they’ve never given you the picture of the lesion for this question? Because they want you to know the probability diagnoses with only this much of information. They want to see if can weigh one condition against others with just that much of information.

Another point: for the exam, fever is a MUST for cellulitis. Although, DVT can cause fever too, and in fact it is one the notorious causes of post-op or postpartum fever, you don’t need fever to make a diagnosis of DVT. We hope it is clear. When fever comes onto the stage, they are gently pushing you towards cellulitis rather than DVT because they are considering you baby doctors and trying not to get you on the ropes. Don’t resist these slight pushes by going like this: but in Harrison …; umm what if ….; but I think …. . Embrace the hints in the exam and use them to your advantage.

We’ll get back to you with more tips for your exam.



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