Answering USMLE Type Questions – Part II

However, you may skip this process or go through them with very quick review, if you are a fairly recent graduate who have just finished your clinical science subjects and consider your knowledge of relevant signs and symptoms and laboratory results of diseases to be quite strong. Even if you are an old graduate with significant clinical experience, you may not be able to skip this step as chances are, you are quite good with common diseases encountered in your practice or specialty but need significant review in diseases that you have not encountered in years.

Now the second step is to reverse the process. Given the signs, symptoms and relevant laboratory results can you identify the disease it is describing. This step is quite important because being able to enumerate the signs, symptoms and relevant lab given a certain disease does not necessarily mean that you will be able to identify the disease given the opposite information. Another problem is that in some cases you need complete information to be able to distinguish between two disease entities while the clinical vignette may give you only partial information. For example given the following information, fever, jaundice, RUQ pain, elevated transaminases and bilirubin, you can only conclude that the patient has acute hepatitis. You need other clues to distinguish between the different types of hepatitis. History of PAN may point to Hepatitis B, while cryoglobinemia may accompany Hepatitis C. Therefore, it is also relevant to know when the clinical description points to a specific disease entity or a group of related clinical entity as it can make the right answer completely different.

You can make use of the tools you use in the first step. For example, you can use UCV by reading through the clinical description while covering the disease being described. However, it suffers from the following disadvantages. First, it is listed by disease entity. Therefore it does not point out differences between diseases with clinically similar presentation which is an essential skill in differential diagnosis. As this step is suppose to accelerate your ability for doing differential diagnosis, it is a major disadvantage. Plus each case resolve to a specific disease entity. As pointed out earlier, in the USMLE, clinical vignettes may point to a group of diseases rather than to a specific disease entity and that can significantly change what can be considered a correct answer.

A better tool is the classical findings part of the Rapid Review section of First Aid for Step 1. It has the additional advantage of  training you to relate keywords to diagnosis which is an important step both in differential diagnosis and pattern recognition. Disadvantage of course lies in that it has only 270++ items which is too few. The classical findings section in the High Yield Fast Facts (HYFF)prep course covers the same 270++ items as in First Aid + 70++ more items in flashcards using the Leitner system which makes it easier to memorize. You can find it in my prep site at http://prep.askdoc-usmle.com and enroll for 2 weeks for a minimal fee. Of course 350 items is still too few.

Also in the same site, is the High Yield Clinical Vignette (HYCF) course, which currently is free to enroll. It has a 300 item physical findings flashcard section which given a group of physical findings, you should identify the disease. Not all physical findings resolve to a specific disease entity as some resolve to group of diseases. 300 items is too small a number to significantly cover Step 1, we need approximately 900 to 1000 items to do so. But the section will be continually upgraded until it covers most of the disease entity covered in Step 1. Enroll to try it out for free.

Now the third and most significant step is to practice identifying diseases given actual clinical vignettes. This is important since unlike in the second step, clinical vignettes tend to present signs and symptoms that are both relevant and irrelevant to the disease concerned leaving you to decide which is which, while in the previous step, only relevant finding is given. Another factor is that instead of giving you an actual interpretation of a symptom or lab test, i.e. hyperkalemia or hypertension, it states a raw number instead like K+ 6.0 or BP 160/110 leaving you to interpret them. These variations can be tougher and it makes sense to practice on them.

There are two ways to implement this step, one using multiple choice questions with the answer choices being disease entities and the other, using flashcard. The flashcard system is actually tougher, since you have to come out with the diagnosis without having choices as clues. The MCQ is easier and have the advantage of helping you learn differential diagnosis as you go through each choices and try to rule in or rule out each diagnosis based on the vignette.

So which of the two choices should you pick? The best is to do both. The flashcard trains you to diagnose without depending on choices. This is a good skill as every time you have to go to answer choices to get the answer, you will be vulnerable to two other test factors, namely two to three step thinking questions and distractors. Remember, in the actual USMLE, you will not have choices that are disease entities and therefore it is harder to use them as clues to the actual diagnosis. So why even bother with MCQ’s? It eases your transition to making diagnosis without any clues, plus the answer choices trains you in differential diagnosis.

Your best choice currently for the third step is Pretest Physical diagnosis. Around 300 of its 500 q’s presents classical clinical vignettes and ask for direct diagnosis. The choices mostly but not all the time, presents appropriate differentials for the case concerned and therefore presents as a good exercise for practicing differentials. You can create flashcards for them so as to train yourself to diagnose without resorting to clues. Alternatively, you can just cover the answer choices and guess the answer.

Significant weakness of Pretest is that all cases are classical. Remember, especially in Step 2 CK and Step 3, a significant number of cases have atypical presentation. It uses a lot of buzzwords. The actual USMLE uses descriptions rather than buzzwords which are usually significant clues. It also interprets signs, symptoms and lab results for you, i.e. hypernatremia rather than Na+ = 165. It almost never give you irrelevant signs, symptoms or lab results which frequently happens in the actual USMLE examination.

The HYCV prep course will eventually contain both flashcard clinical vignettes and MCQ clinical vignettes. It will also contain both classical cases and atypical cases and labeled as such so you can escalate your training according to your skill level. Watch out for announcements on when they will be available.

Now depending on your skill with clinical vignettes, you can do all three steps or skip them altogether. You can also do some but not all the steps or in different intensity. However, do not presume that since you are able to answer clinical vignettes questions that you do not have any problems with them. Even small problems can lower your scores and increasing your skills can significantly improve them.

Now that you have trained yourself to use pattern recognition in clinical vignettes, is there anything you need to watch out for in the actual examination? First, as in my case, there will be times when you have to resort to differential diagnosis to diagnose a case. Don’t hesitate to do so if needed. But resorting to them only occasionally can save you a lot of precious time which is quite a rare commodity in the USMLE. Second, occasionally, after diagnosing the case, the answer choices do not contain anything relevant to your diagnosis. Athough the problem maybe that you lack the knowledge being asked in the question, it can also mean that you got the wrong diagnosis. So it may make sense to go through the differentials of your initial diagnosis to see if any of the choices will fit better with the other diagnosis. Although it does not automatically make it the right choice, it does present you with a logical way to approach the question rather than making a wild guess or panicking.

I had initially thought that we would be able to finish this in two parts, but it actually is significantly longer than expected. So this topic might go into 4 parts to finish. We will discuss how to tackle two to three step thinking questions and distractors next time emphasizing what to do during exam preparations and what to do during the actual examination itself.