How to Approach USMLE Style Questions

It takes skill to correctly answer USMLE-style questions with consistency. More likely than not, we’ve all had those questions that leave us scratching our heads, asking, “how did I get that one wrong?”. Misdiagnosis and misinterpretation are the most frustrating reasons for incorrect answers because you know that you’ve studied and mastered the concepts. Here are my recommendations for minimizing these errors.

1. Read the last line first

This is standard advice for two excellent reasons. The first is that there are often one or two questions per block for which the last line is all you need. Rapidly answering these questions when you see them can give you an extra one or two minutes per block. Every second counts on the USMLE, so an extra minute or two to answer other questions becomes invaluable. An example is the vignette below.

“A 70-year-old woman presents to your office because of a lump in her left breast that was palpated on self-examination a week ago. Skipped beats are noted on radial artery palpation, but her vital signs are otherwise within normal limits. You refer her for mammography and subsequent biopsy of the mass, which reveals medullary carcinoma with limited local infiltration. Treatment with paclitaxel is initiated. Which of the following best describes the mechanism of action of this medication?”

Reading the last line of the vignette should prompt a scan of the preceding line to find the medication in question. However, no information could possibly be given in the rest of the question that would change the mechanism of action of paclitaxel, so it is unnecessary to go through it.

The second reason for reading the last line first is that for the vast majority of questions where you actually need to analyze the whole vignette, the last line would let you know what to look for. This may be a diagnosis, an association, a side effect, an indication, a contraindication, etc.

2. Leave the options till you have an answer or idea

In my experience as a coach, I have encountered some USMLE experts who recommend glancing at the options. Others recommend avoiding this at first. Those who say to look at the options after the last line say that it provides an idea of what area of knowledge is being tested (e.g., biochemistry, pediatrics, psychiatry, etc.). This information has limited utility but stands the risk of introducing bias during analysis of the question stem. I especially discourage the practice of working from answer to question, which is common among candidates. This practice increases the likelihood of falling prey to distractors and other tripwires in questions. It takes more discipline to think through the question before settling on a direction for answering, but this results in more correct answers.

3. Always highlight age, sex, timeline and abnormal vital signs

These pieces of information are often massive clues to the correct answer. Overlooking even one of them as candidates sometimes do can lead to misdiagnosis. For instance, pemphigus vulgaris and staphylococcal scalded skin syndrome can both manifest with flaccid bullae and a positive Nikolsky sign. However, if the patient is three months old, pemphigus vulgaris is unlikely. Chest pain that started thirty minutes ago likely has a different etiology than one that began two weeks ago. As for vital signs, they can only be normal or abnormal. If they are within normal ranges, then spend less time on them. If abnormal, use the highlight function and determine whether the value is too high or too low, as well as how that affects your analysis.

4. Generate and refine a working diagnosis as you read through

When working through practice questions with my students, I encourage them, where applicable, to generate a working assessment after the first one or two sentences. This assessment does not have to be correct or specific. It may even be as broad as “intracranial pathology.” The key is that each new piece of information will then do one of three things to the working diagnosis. Either the new information will bolster the current assessment, introduce a new diagnosis, or do nothing to the assessment. Therefore, for every sentence after the first assessment, it is essential to determine which of these three effects the new information has had.

The result of analyzing the question in this way is that in the vast majority of cases, you would have an answer to the question by the time you reach the end. This method is more effective and time-efficient than waiting till the end of the question to reach a conclusion and then having to re-read the question or portions of it.

5. Know a distractor when you see it

There are two kinds of distractors on USMLE-style questions. The first kind exists as a piece of information within the question stem, meant to introduce confusion and misdiagnosis for candidates who haven’t fully mastered the concepts. You can identify distractors of this type because their implications are entirely incongruent with all or most of the other clues in the question. An example of such a distractor would be the family history in the following vignette.

“A 37-year-old African American male presents with a chief complaint of cough, fatigue, and weight loss for the past three months. The cough is productive of whitish sputum that is frequently tinged with blood. Imaging shows a centrally located solitary nodule in the right middle lobe of the lung. Family history is significant for metastatic prostate cancer in the patient’s father and paternal grandfather. Biopsy demonstrates epithelial cells with several intercellular bridges. What is the most likely diagnosis?”

The clinical picture in this vignette is consistent with lung cancer. A candidate faced with this question will then want to determine if this is a primary tumor or a metastasis (considering the family history). In this case, there is only one indicator (family history) that this might be a metastasis, and that indicator doesn’t directly affect the patient. The imaging and biopsy findings are objective clues pointing to primary squamous cell carcinoma. When there is one piece of information that seems to contradict every other, but then does not do so definitively, it is likely to be a distractor.

The second kind of distractor is an answer choice designed to draw attention away from the correct one. When faced with distractors like this, candidates often narrow their choices to two potential answers and then have difficulty selecting between them. If this happens, don’t spend time waffling between the two options. Instead, read the question stem a second time, especially the pertinent information you highlighted. You would be looking for one or more pieces of information that strongly supports or goes against one of the two choices. I find it helps to tell myself, “I’m missing something here; what is it?”. This technique often enables you to choose the correct answer, but if you still find yourself confused, you may not have sufficient mastery of the two concepts to differentiate between them. In that case, guess, mark the question in case you have time later, and move on.

6. Build good clinical pictures

A clinical picture is a conceptual summary of a disease that allows you to recognize it in questions. This means you build clinical pictures while reviewing material and then again when answering a question. If done correctly, you would have a mental library of clinical pictures. You would then build a clinical picture from each question stem, and attempt to match it to the ones you already know. A good clinical picture has five main components, with minor additions in specific cases. These are

  • Root problem/pathogenesis – What went wrong that caused this disease?
  • History – What would the patient, their friend, or relative tell you about the symptoms?
  • Physical examination findings – What would you find when you examine the patient?
  • Diagnostics – What studies would you order based on the tentative assessment from the H&P?
  • Plan – How would you treat the condition?

Effective use of clinical pictures demonstrates adequate mastery that would enhance your diagnostic skills and make you faster while answering questions.

7. Correctly interpret graphs and images

Every graph tells a story. When it comes to reading one, it is critical to orient yourself to the axes and caption, if any. The Y-axis of any graph shows how the variable on it changes with respect to the variable on the X-axis. Attempting to understand a graph without orienting yourself to these variables will likely result in a flawed analysis.

Histological images often elicit a mental groan from candidates that come across them. The key to correctly reading a microscopic image is to take some time to identify features of the image that stand out. Ask yourself questions like “what cell types can I see in this picture?”, “What is the normal histology of this tissue, and how does this deviate from it, if at all?”. If a feature immediately stands out in the slide, such as a granuloma or an obviously abnormal cell, try to recall where you’ve seen it before. Actually try, before you write off the slide because you can often have an “oh, oh, I know this” moment if you do. Of course, this requires mastery of normal and abnormal histologic features before the test. Similar principles apply to x-rays, MRIs, CT scans, and immunofluorescence.

8. Manage time judiciously

Time management is often a significant problem for candidates during practice tests. Here are some ways to minimize the effects of having only ninety seconds per question.

  • Learn to reach a conclusion by the end of reading a question the first time. See number 4 above. Going over each vignette multiple times is highly detrimental to time management.
  • Keep an eye on the clock but not to the point that it distracts you. For instance, you can check the clock about every five questions. Since you have 1.5 minutes per question, you should have used up at most 7.5 minutes every five questions. After five questions, you should have 52.5 minutes. After ten questions, you should have 45 minutes. And so on, with some variation for longer and shorter questions. Ideally, you would finish a block with a few minutes to spare for reviewing questions you marked, but just being able to finish without panicking about time is a great place to be. If you can keep closer tabs on the clock (such as subtracting 1.5 minutes for every question or 3 minutes for every two questions), your time management will be better.
  • Know when to guess, mark the question and move on to the next. See number 5 above.
  • Memorize commonly encountered lab values. Every second is valuable when answering questions. Minimizing the time spent searching through the lab sheet is thus very helpful for time management. By my test days, I had memorized nearly every lab value. I only had to open up the lab values for relatively obscure ones like normal IgE levels. This helped tremendously and can be done in small bits and pieces. When you need a lab value during practice tests, commit it to memory while reviewing the explanation. The next time you need it, try to recall it. Only pull it up if you fail to do so. By test day, you would know normal levels for electrolytes, ABG, hormones, proteins, hemoglobin, etc.

In Conclusion

There are several factors that go into being a good test-taker. I have discussed the biggest ones I know based on personal experience and the hundreds of hours I have spent coaching students. I hope this article leaves you a little better prepared for USMLE-stye questions, and I would love to hear your opinions and experiences in this area, so please consider leaving a comment. In addition, if you are considering personalized guidance during

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